Leslie Yeo

Electrokinetic actuation of low conductivity dielectric liquids

Publisher: Elsevier BV

Date: 06-2009

DOI: 10.1016/J.SNB.2009.04.036

A Novel Acoustomicrofluidic Nebulization Technique Yielding New Crystallization Morphologies

Publisher: Wiley

Date: 04-12-2017

DOI: 10.1002/ADMA.201602040

Abstract: A novel acoustic microfluidic nebulization platform is demonstrated, which, due to its unique ability to access intermediate evaporation rate regimes-significantly faster than that in slow solvent evaporation but considerably below that achieved in spray drying, is capable of producing novel crystal morphologies that have yet to be reported in both model inorganic and organic systems. In addition, the potential for simultaneously encapsulating single crystals within a biodegradable polymeric coating in a single simultaneous step together with the crystallization process as the solvent evaporates during nebulization is briefly shown. The platform not only has the potential to be highly scalable by employing a large number of these low-cost miniature devices in parallel to achieve industrially relevant particle production rates, but could also be advantageous over conventional spray drying in terms of energy utilization, given the tremendous efficiency associated with the high-frequency ultrasonic microdevice as well as its ambient temperature operation.

ZnO/sapphire based layered surface acoustic wave devices for microfluidic applications

Publisher: IEEE

Date: 02-2011

DOI: 10.1109/NEMS.2011.6017330

Evaporative self-assembly of gold nanorings via a surface acoustic wave atomization

Publisher: SPIE

Date: 21-12-2011

DOI: 10.1117/12.903172

MicroPIV and micromixing study of corona wind induced microcentrifugation flows in a cylindrical cavity

Publisher: Springer Science and Business Media LLC

Date: 26-05-2010

DOI: 10.1007/S10404-009-0459-9

Engineering of Nebulized Metal–Phenolic Capsules for Controlled Pulmonary Deposition

Publisher: Wiley

Date: 10-01-2020

DOI: 10.1002/ADVS.201902650

Amplitude modulation schemes for enhancing acoustically-driven microcentrifugation and micromixing

Publisher: AIP Publishing

Date: 09-2016

DOI: 10.1063/1.4963103

Abstract: The ability to drive microcentrifugation for efficient micromixing and particle concentration and separation on a microfluidic platform is critical for a wide range of lab-on-a-chip applications. In this work, we investigate the use of litude modulation to enhance the efficiency of the microcentrifugal recirculation flows in surface acoustic wave microfluidic systems, thus concomitantly reducing the power consumption in these devices for a given performance requirement—a crucial step in the development of miniaturized, integrated circuits for true portable functionality. In particular, we show that it is possible to obtain an increase of up to 60% in the acoustic streaming velocity in a microdroplet with kHz order modulation frequencies due to the intensification in Eckart streaming the streaming velocity is increasing as the modulation index is increased. Additionally, we show that it is possible to exploit this streaming enhancement to effect improvements in the speed of particle concentration by up to 70% and the efficiency of micromixing by 50%, together with a modest decrease in the droplet temperature.

Fabrication of microfluidic devices using polydimethylsiloxane

Publisher: AIP Publishing

Date: 15-03-2010

DOI: 10.1063/1.3259624

Abstract: Polydimethylsiloxane (PDMS) is nearly ubiquitous in microfluidic devices, being easy to work with, economical, and transparent. A detailed protocol is provided here for using PDMS in the fabrication of microfluidic devices to aid those interested in using the material in their work, with information on the many potential ways the material may be used for novel devices.

Surface vibration induced spatial ordering of periodic polymer patterns on a substrate

Publisher: American Chemical Society (ACS)

Date: 17-09-2008

DOI: 10.1021/LA802255B

Abstract: We demonstrate the possibility of producing regular, long-range, spatially ordered polymer patterns without requiring the use of physical or chemical templating through the interfacial destabilization of a thin polymer film driven by surface acoustic waves (SAWs). The periodicity and spot size of the pattern are observed to be dependent on a single parameter, that is, the SAW frequency (or wavelength), therefore offering a rapid, simple, yet novel method for self-organized regular spatial polymer pattern formation that is far more tunable than conventional polymer patterning procedures.

Piezoelectric ultrasonic resonant micromotor with a volume of less than 1 mm³ for use in medical microbots

Publisher: IEEE

Date: 05-2009

DOI: 10.1109/ROBOT.2009.5152400

Rapid microscale in-gel processing and digestion of proteins using surface acoustic waves

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/C001501F

Abstract: A new method for in-gel s le processing and tryptic digestion of proteins is described. S le preparation, rehydration, in situ digestion and peptide extraction from gel slices are dramatically accelerated by treating the gel slice with surface acoustic waves (SAWs). Only 30 minutes total workflow time is required for this new method to produce base peak chromatograms (BPCs) of similar coverage and intensity to those observed for traditional processing and overnight digestion. Simple set up, good reproducibility, excellent peptide recoveries, rapid turnover of s les and high confidence protein identifications put this technology at the fore-front of the next generation of proteomics s le processing tools.

Vibration-induced deagglomeration and shear-induced alignment of carbon nanotubes in air

Publisher: Wiley

Date: 15-12-2015

DOI: 10.1002/ADFM.201402976

A simple predictive tool for modelling phase inversion in liquid-liquid dispersions

Publisher: Elsevier BV

Date: 03-2002

DOI: 10.1016/S0009-2509(01)00443-2

Acoustic-Excitonic Coupling for Dynamic Photoluminescence Manipulation of Quasi - 2D MoS 2 Nanoflakes

Publisher: Wiley

Date: 12-03-2015

DOI: 10.1002/ADOM.201500034

Particle concentration and mixing in microdrops driven by focused surface acoustic waves

Publisher: AIP Publishing

Date: 07-2008

DOI: 10.1063/1.2951467

Abstract: We report the use of focused surface acoustic waves (SAWs) generated on 128° rotated Y-cut X-propagating lithium niobate (LiNbO3) for enhancing the actuation of fluids and the manipulation of particle suspensions at microscale dimensions. In particular, we demonstrate increased efficiency and speed in carrying out particle concentration/separation and in generating intense micromixing in microliter drops within which acoustic streaming is induced due to the focused SAW beneath the drop. Concentric circular and elliptical single-phase unidirectional transducers (SPUDTs) were used to focus the SAW. We benchmark our results against a straight SPUDT which does not cause focusing of the SAW. Due to the increased wave intensity and asymmetry of the wave, we found both circular and elliptical SPUDTs concentrate particles in under 1 s, which is one order of magnitude faster than the straight SPUDT and several orders of magnitude faster than conventional microscale devices. The concentric circular SPUDT was found to be most effective at a given input power since it generated the largest azimuthal velocity gradient within the fluid to drive particle shear migration. On the other hand, the concentric elliptical SPUDT generated the highest micromixing intensity due to the more narrowly focused SAW radiation that substantially enhances acoustic streaming in the fluid.

Acoustomicrofluidic Synthesis of Pristine Ultrathin Ti₃C₂T_z MXene Nanosheets and Quantum Dots

Publisher: American Chemical Society (ACS)

Date: 29-06-2021

DOI: 10.1021/ACSNANO.1C03428

Abstract: The conversion of layered transition metal carbides and/or nitrides (MXenes) into zero-dimensional structures with thicknesses and lateral dimensions of a few nanometers allows these recently discovered materials with exceptional electronic properties to exploit the additional benefits of quantum confinement, edge effects, and large surface area. Conventional methods for the conversion of MXene nanosheets and quantum dots, however, involve extreme conditions such as high temperatures and/or harsh chemicals that, among other disadvantages, lead to significant degradation of the material as a consequence of their oxidation. Herein, we show that the large surface acceleration-on the order of 10 million

Rapid generation of protein aerosols and nanoparticles via surface acoustic wave atomization

Publisher: IOP Publishing

Date: 08-10-2008

DOI: 10.1088/0957-4484/19/45/455103

Abstract: We describe the fabrication of a surface acoustic wave (SAW) atomizer and show its ability to generate monodisperse aerosols and particles for drug delivery applications. In particular, we demonstrate the generation of insulin liquid aerosols for pulmonary delivery and solid protein nanoparticles for transdermal and gastrointestinal delivery routes using 20 MHz SAW devices. Insulin droplets around 3 µm were obtained, matching the optimum range for maximizing absorption in the alveolar region. A new approach is provided to explain these atomized droplet diameters by returning to fundamental physical analysis and considering viscous-capillary and inertial-capillary force balance rather than employing modifications to the Kelvin equation under the assumption of parametric forcing that has been extended to these frequencies in past investigations. In addition, we consider possible mechanisms by which the droplet ejections take place with the aid of high-speed flow visualization. Finally, we show that nanoscale protein particles (50-100 nm in diameter) were obtained through an evaporative process of the initial aerosol, the final size of which could be controlled merely by modifying the initial protein concentration. These results illustrate the feasibility of using SAW as a novel method for rapidly producing particles and droplets with a controlled and narrow size distribution.

Exploitation of surface acoustic waves to drive size-dependent microparticle concentration within a droplet

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/C004822D

Abstract: Ultrafast particle and cell concentration is essential to the success of subsequent analytical procedures and the development of miniaturized biological and chemical sensors. Here, surface acoustic wave (SAW) devices were used to excite a MHz-order acoustic wave that propagates into a microlitre droplet to drive spatial concentration and separation of two different sized suspended microparticles. The rapid concentration process, occurring within just three seconds to facilitate spatial partitioning between the two particle species, exploited two acoustic phenomena acting on the suspended particles: the drag force arising from acoustic streaming and the acoustic radiation force, both driving particles in different directions. This study elucidates the very intricate and interesting interplay of physics between fluid drag and acoustic forcing on the particles within a droplet, and, for the first time, demonstrates the existence of a frequency-dependent crossover particle size that can be used to effect species partitioning: depending on the operating frequency of the SAW device and the particle size, it is possible to cause one phenomenon to dominate over the other. A theoretical analysis revealed the extent to which each force would affect the particle trajectory (particle size range: 2-31 μm), subsequently verified through experimentation. Based on these findings, 6 and 31 μm polystyrene particles were successfully partitioned in a water droplet using a 20 MHz SAW device. This study reveals the suitability of using acoustic actuation methods for the useful partitioning of particle species within a discrete fluid volume.

Stability and efficacy of synthetic cationic antimicrobial peptides nebulized using high frequency acoustic waves

Publisher: AIP Publishing

Date: 05-2016

DOI: 10.1063/1.4953548

Abstract: Surface acoustic wave (SAW), a nanometer litude electroelastic wave generated and propagated on low-loss piezoelectric substrates (such as LiNbO3), is an extremely efficient solid–fluid energy transfer mechanism. The present study explores the use of SAW nebulization as a solution for effective pulmonary peptide delivery. In vitro deposition characteristics of the nebulized peptides were determined using a Next Generation Cascade Impactor. 70% of the peptide-laden aerosols generated were within a size distribution favorable for deep lung distribution. The integrity of the nebulized peptides was found to be retained, as shown via mass spectrometry. The anti-mycobacterial activity of the nebulized peptides was found to be uncompromised compared with their non-nebulized counterparts, as demonstrated by the minimum inhibition concentration and the colony forming inhibition activity. The peptide concentration and volume recoveries for the SAW nebulizer were significantly higher than 90% and found to be insensitive to variation in the peptide sequences. These results demonstrate the potential of the SAW nebulization platform as an effective delivery system of therapeutic peptides through the respiratory tract to the deep lung.

Ultrafast Acoustofluidic Exfoliation of Stratified Crystals

Publisher: Wiley

Date: 30-03-2018

DOI: 10.1002/ADMA.201704756

Abstract: While the remarkable properties of 2D crystalline materials offer tremendous opportunities for their use in optics, electronics, energy systems, biotechnology, and catalysis, their practical implementation largely depends critically on the ability to exfoliate them from a 3D stratified bulk state. This goal nevertheless remains elusive, particularly in terms of a rapid processing method that facilitates high yield and dimension control. An ultrafast multiscale exfoliation method is reported which exploits the piezoelectricity of stratified materials that are noncentrosymmetric in nature to trigger electrically-induced mechanical failure across weak grain boundaries associated with their crystal domain planes. In particular, it is demonstrated that microfluidic nebulization using high frequency acoustic waves exposes bulk 3D piezoelectric crystals such as molybdenum disulphide (MoS

Acoustically enhanced heat transport

Publisher: AIP Publishing

Date: 2016

DOI: 10.1063/1.4939757

Abstract: We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 106 Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration litudes (ξs ∼ 10−9 m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration litude (ξs ∼ 10−8 m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement litude on the order of 10−8 m with 106 Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

Simulation studies of phase inversion in agitated vessels using a Monte Carlo technique

Publisher: Elsevier BV

Date: 04-2002

DOI: 10.1006/JCIS.2001.8159

Abstract: A speculative study on the conditions under which phase inversion occurs in agitated liquid-liquid dispersions is conducted using a Monte Carlo technique. The simulation is based on a stochastic model, which accounts for fundamental physical processes such as drop deformation, breakup, and coalescence, and utilizes the minimization of interfacial energy as a criterion for phase inversion. Profiles of the interfacial energy indicate that a steady-state equilibrium is reached after a sufficiently large number of random moves and that predictions are insensitive to initial drop conditions. The calculated phase inversion holdup is observed to increase with increasing density and viscosity ratio, and to decrease with increasing agitation speed for a fixed viscosity ratio. It is also observed that, for a fixed viscosity ratio, the phase inversion holdup remains constant for large enough agitation speeds. The proposed model is therefore capable of achieving reasonable qualitative agreement with general experimental trends and of reproducing key features observed experimentally. The results of this investigation indicate that this simple stochastic method could be the basis upon which more advanced models for predicting phase inversion behavior can be developed.

Poloidal flow and toroidal particle ring formation in a sessile drop driven by megahertz order vibration

Publisher: American Chemical Society (ACS)

Date: 11-09-2014

DOI: 10.1021/LA502301F

Abstract: Poloidal flow is curiously formed in a microliter sessile water drop over 157-225 MHz because of acoustic streaming from three-dimensional standing Lamb waves in a lithium niobate substrate. The flow possesses radial symmetry with downwelling at the center and upwelling around the periphery of the drop. Outside this frequency range, the attenuation occurs over a length scale incompatible with the drop size and the poloidal flow vanishes. Remarkably, shear-induced migration was found to drive toroidal particle ring formation with diameters inversely proportional to the frequency of the acoustic irradiation.

Extensional flow of low-viscosity fluids in capillary bridges formed by pulsed surface acoustic wave jetting

Publisher: IOP Publishing

Date: 02-2011

DOI: 10.1088/1367-2630/13/2/023005

The dynamics of Marangoni-driven local film drainage between two drops

Publisher: Elsevier BV

Date: 09-2001

DOI: 10.1006/JCIS.2001.7743

The axial-torsional vibration of pretwisted beams

Publisher: Elsevier BV

Date: 03-2009

DOI: 10.1016/J.JSV.2008.09.016

Micromotor of less than 1 mm³ volume for in vivo medical procedures

Publisher: IEEE

Date: 02-2009

DOI: 10.1109/ICQNM.2009.14

Surface acoustic wave micromotor with arbitrary axis rotational capability

Publisher: AIP Publishing

Date: 21-11-2011

DOI: 10.1063/1.3662931

Abstract: A surface acoustic wave (SAW) actuated rotary motor is reported here, consisting of a millimeter-sized spherical metal rotor placed on the surface of a lead zirconate titanate piezoelectric substrate upon which the SAW is made to propagate. At the design frequency of 3.2 MHz and with a fixed preload of 41.1 μN, the maximum rotational speed and torque achieved were approximately 1900 rpm and 5.37 μN-mm, respectively, producing a maximum output power of 1.19 μW. The surface vibrations were visualized using laser Doppler vibrometry and indicate that the rotational motion arises due to retrograde elliptical motions of the piezoelectric surface elements. Rotation about orthogonal axes in the plane of the substrate has been obtained by using orthogonally placed interdigital electrodes on the substrate to generate SAW impinging on the rotor, offering a means to generate rotation about an arbitrary axis in the plane of the substrate.

Prospective Subunit Nanovaccine against Mycobacterium tuberculosis Infection─Cubosome Lipid Nanocarriers of Cord Factor, Trehalose 6,6′ Dimycolate

Publisher: American Chemical Society (ACS)

Date: 06-2023

DOI: 10.1021/ACSAMI.3C04063

HYbriD Resonant Acoustics (HYDRA)

Publisher: Wiley

Date: 07-01-2016

DOI: 10.1002/ADMA.201504861

Abstract: The existence of what is termed here as a surface-reflected bulk wave is unraveled and elucidated, and it is shown, quite counterintuitively, that it is possible to obtain an order-of-magnitude improvement in microfluidic manipulation efficiency, and, in particular, nebulization, through a unique combination of surface and bulk waves without increasing complexity or cost.

Acoustically-mediated intracellular delivery

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8NR02898B

Abstract: High frequency sound waves enable enhanced cytosolic transport of molecular cargo into cells without the formation of pores.

Film drainage between two surfactant-coated drops colliding at constant approach velocity

Publisher: Elsevier BV

Date: 2003

DOI: 10.1016/S0021-9797(02)00033-4

Abstract: The drainage of the intervening continuous phase film between two drops approaching each other at constant velocity under the influence of insoluble surfactant is investigated. The mathematical model to be solved is a coupled pair of fourth-order nonlinear partial differential equations which arise from the relationships governing the evolution of the film thickness and the surfactant interfacial concentration in the lubrication approximation. We adopt a simplified approach which uses lubrication theory to describe the flow within the drop, marking a departure from the conventional framework in which Stokes flow is assumed. When the model is solved numerically together with the relevant initial and boundary conditions, the results obtained are compared with those found in the literature using the "boundary integral" method to solve for the flow in the drop phase. The close agreement between the results inspires confidence in the predictions of the simplified approach adopted. The analysis on the effect of insoluble surfactant indicates that its presence retards the drainage of the film: The fully immobile interface limit is recovered even in the presence of a small amount of surfactant above a critical concentration film rupture is either prolonged or prevented. The retardation of the film was attributed to gradients of interfacial tension which gave rise to the Marangoni effect. A study of the influence of various system parameters on the drainage dynamics was conducted and three regimes of drainage and possible rupture were identified depending on the relative magnitudes of the drop approach velocity and the van der Waals interaction force: Nose rupture, rim rupture, and film immobilization and flattening. Finally, the possibility of forming secondary droplets by encapsulating the continuous phase film into the coalesced drop at rupture was examined and quantified in light of these regimes.

Evaporative self-assembly assisted synthesis of polymeric nanoparticles by surface acoustic wave atomization

Publisher: IOP Publishing

Date: 04-03-2008

DOI: 10.1088/0957-4484/19/14/145301

Abstract: We demonstrate a straightforward and rapid atomization process driven by surface acoustic waves that is capable of continuously producing spherical monodispersed submicron poly-ε-caprolactone particle aggregates between 150 and 200 nm, each of which are composed of nanoparticles of 5-10 nm in diameter. The size and morphologies of these particle assemblies were determined using dynamic light scattering, atomic force microscopy and transmission electron microscopy. Through scaling theory, we show that the larger particle aggregates are formed due to capillary instabilities lified by the acoustic forcing whereas the smaller particulates that form the aggregates arise due to a nucleate templating process as a result of rapid spatially inhomogeneous solvent evaporation. Minimization of the free energy associated with the evaporative process yields a critical cluster size for a single nucleus in the order of 10 nm, which roughly corresponds with the dimensions of the sub-50 nm particulates.

UV epoxy bonding for enhanced SAW transmission and microscale acoustofluidic integration

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2LC40085E

Abstract: Surface acoustic waves (SAWs) are appealing as a means to manipulate fluids within lab-on-a-chip systems. However, current acoustofluidic devices almost universally rely on elastomeric materials, especially PDMS, that are inherently ill-suited for conveyance of elastic energy due to their strong attenuation properties. Here, we explore the use of a low-viscosity UV epoxy resin for room temperature bonding of lithium niobate (LiNbO(3)), the most widely used anisotropic piezoelectric substrate used in the generation of SAWs, to standard micromachined superstrates such as Pyrex® and silicon. The bonding methodology is straightforward and allows for reliable production of sub-micron bonds that are capable of enduring the high surface strains and accelerations needed for conveyance of SAWs. Devices prepared with this approach display as much as two orders of magnitude, or 20 dB, improvement in SAW transmission compared to those fabricated using the standard PDMS elastomer. This enhancement enables a broad range of applications in acoustofluidics that are consistent with the low power requirements of portable battery-driven circuits and the development of genuinely portable lab-on-a-chip devices. The method is exemplified in the fabrication of a closed-loop bidirectional SAW pumping concept with applications in micro-scale flow control, and represents the first demonstration of closed channel SAW pumping in a bonded glass/LiNbO(3) device.

Microfluidic Devices for Bioapplications

Publisher: Wiley

Date: 11-11-2010

DOI: 10.1002/SMLL.201000946

Abstract: Harnessing the ability to precisely and reproducibly actuate fluids and manipulate bioparticles such as DNA, cells, and molecules at the microscale, microfluidics is a powerful tool that is currently revolutionizing chemical and biological analysis by replicating laboratory bench-top technology on a miniature chip-scale device, thus allowing assays to be carried out at a fraction of the time and cost while affording portability and field-use capability. Emerging from a decade of research and development in microfluidic technology are a wide range of promising laboratory and consumer biotechnological applications from microscale genetic and proteomic analysis kits, cell culture and manipulation platforms, biosensors, and pathogen detection systems to point-of-care diagnostic devices, high-throughput combinatorial drug screening platforms, schemes for targeted drug delivery and advanced therapeutics, and novel biomaterials synthesis for tissue engineering. The developments associated with these technological advances along with their respective applications to date are reviewed from a broad perspective and possible future directions that could arise from the current state of the art are discussed.

Electrokinetic Actuation of Low Conductivity Dielectric Liquids

Publisher: ASMEDC

Date: 2008

DOI: 10.1115/ICNMM2008-62239

Abstract: There has been some amount of confusion over the origin of electrohydrodynamic phenomena responsible for the actuation of dielectric fluids in the presence of an electric field. Previous studies have accounted for the possibility of conduction pumping, ion drag pumping and induction pumping as driving mechanisms but have ignored the possibility of Maxwell (electric) pressure driven flow. Until recently, this mechanism has been poorly understood and as a result has often been overlooked. This paper demonstrates how a Maxwell pressure gradient can induce flow in dielectric liquids in the presence of a non-uniform field. We derive, from first principles using lubrication theory, an expression for the flow velocity which exhibits a quadratic dependence on the applied voltage and also proportionality to the ratio of the permittivity and viscosity. The theoretical predictions are supported by experimental results. Although we have examined the phenomenon for a particular class of dielectric liquids, it is believed that this mechanism could well be responsible for the actuation of other low conductivity dielectric fluids previously attributed to conduction or ion drag pumping. In any case, we discuss ways to identify the dominant mechanism by comparing the salient features for a given type of flow.

Plug-and-actuate on demand: multimodal individual addressability of microarray plates using modular hybrid acoustic wave technology

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C7LC01099K

Abstract: Integrating versatile microfluidic liquid handling technology with existing drug discovery laboratory formats.

Viscoelastic flow in a two-dimensional collapsible channel

Publisher: Elsevier BV

Date: 10-2010

DOI: 10.1016/J.JNNFM.2010.06.005

Modelling and testing of a piezoelectric ultrasonic micro-motor suitable for in vivo micro-robotic applications

Publisher: IOP Publishing

Date: 15-10-2010

DOI: 10.1088/0960-1317/20/11/115018

Modeling of Light Propagation through Biological Tissues: A Novel Approach

Publisher: IEEE

Date: 2007

DOI: 10.1109/FBIT.2007.22

Transmitting high power rf acoustic radiation via fluid couplants into superstrates for microfluidics

Publisher: AIP Publishing

Date: 12-01-2009

DOI: 10.1063/1.3049128

Abstract: In this study, surface acoustic radiation is refracted from lithium niobate through a fluid coupling into a thin glass plate. We demonstrate and explain its propagation as an asymmetric Lamb wave along the glass plate with sufficient power to transport fluid droplets across the glass surface at 8 mm/s. Such technology enables the use of standard processing techniques to fabricate an inexpensive and disposable microfluidics device together with the power transmission capabilities of surface acoustic wave devices with an easily renewable coupling.

Calcium-dependent cAMP mediates the mechanoresponsive behaviour of endothelial cells to high-frequency nanomechanostimulation

Publisher: Elsevier BV

Date: 2023

DOI: 10.1016/J.BIOMATERIALS.2022.121866

Continuous flow actuation between external reservoirs in small-scale devices driven by surface acoustic waves

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C3LC50933H

Abstract: We have designed and characterized a surface acoustic wave (SAW) fluid actuation platform that significantly improves the transmission of sound energy from the SAW device into the fluid in order to obtain enhanced performance. This is in distinct contrast to previous SAW microfluidic devices where the SAW substrate is simply interfaced with a microchannel without due consideration given to the direction in which the sound energy is transmitted into the fluid, thus resulting in considerable reflective and dissipative losses due to reflection and absorption at the channel walls. For the first time, we therefore demonstrate the ability for continuous fluid transfer between independent reservoirs driven by the SAW in a miniature device and report the associated pressure-flow rate relationship, in which a maximum flow rate of 100 μl min(-1) and pressure of 15 Pa were obtained. The pumping efficiency is observed to increase with input power and, at peak performance, offers an order-of-magnitude improvement over that of existing SAW micropumps that have been reported to date.

Assessment of the potential of a high frequency acoustomicrofluidic nebulisation platform for inhaled stem cell therapy

Publisher: Oxford University Press (OUP)

Date: 2016

DOI: 10.1039/C5IB00206K

Abstract: This study demonstrates the use of a novel high frequency acoustic nebulisation platform as an effective aerosolisation technique for inhaled mesenchymal stem cell (MSC) therapy.

Laguerre Runge--Kutta--Fehlberg Method for Simulating Laser Pulse Propagation in Biological Tissue

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 2008

DOI: 10.1109/JSTQE.2007.913971

Electrohydrodynamic surface microvortices for mixing and particle trapping

Publisher: AIP Publishing

Date: 05-06-2006

DOI: 10.1063/1.2212275

Abstract: We report a free-surface electrohydrodynamic flow phenomenon driven by an ionic wind mechanism induced by a high frequency gas-phase ac field (& kHz). Intense vortices & cm∕s are generated above a critical voltage, beyond which the vortices break down to spawn off new vortex pairs leading to a cascade of vortices over a continuum of length scales the mixing efficiency approaches a turbulent-like state. Colloidal particles are attracted and aggregated into planar crystal structures within the vortices by a combination of dielectrophoresis and shear-induced diffusion.

Nozzleless spray cooling using surface acoustic waves

Publisher: Elsevier BV

Date: 2015

DOI: 10.1016/J.JAEROSCI.2014.10.004

Sonomechanobiology: Vibrational stimulation of cells and its therapeutic implications

Publisher: AIP Publishing

Date: 21-04-2023

DOI: 10.1063/5.0127122

Abstract: All cells possess an innate ability to respond to a range of mechanical stimuli through their complex internal machinery. This comprises various mechanosensory elements that detect these mechanical cues and erse cytoskeletal structures that transmit the force to different parts of the cell, where they are transcribed into complex transcriptomic and signaling events that determine their response and fate. In contrast to static (or steady) mechanostimuli primarily involving constant-force loading such as compression, tension, and shear (or forces applied at very low oscillatory frequencies ( ≤ 1 Hz) that essentially render their effects quasi-static), dynamic mechanostimuli comprising more complex vibrational forms (e.g., time-dependent, i.e., periodic, forcing) at higher frequencies are less well understood in comparison. We review the mechanotransductive processes associated with such acoustic forcing, typically at ultrasonic frequencies ( & 20 kHz), and discuss the various applications that arise from the cellular responses that are generated, particularly for regenerative therapeutics, such as exosome biogenesis, stem cell differentiation, and endothelial barrier modulation. Finally, we offer perspectives on the possible existence of a universal mechanism that is common across all forms of acoustically driven mechanostimuli that underscores the central role of the cell membrane as the key effector, and calcium as the dominant second messenger, in the mechanotransduction process.

Uniform mixing in paper-based microfluidic systems using surface acoustic waves

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2LC21065G

Abstract: Paper-based microfluidics has recently received considerable interest due to their ease and low cost, making them extremely attractive as point-of-care diagnostic devices. The incorporation of basic fluid actuation and manipulation schemes on paper substrates, however, afford the possibility to extend the functionality of this simple technology to a much wider range of typical lab-on-a-chip operations, given its considerable advantages in terms of cost, size and integrability over conventional microfluidic substrates. We present a convective actuation mechanism in a simple paper-based microfluidic device using surface acoustic waves to drive mixing. Employing a Y-channel structure patterned onto paper, the mixing induced by the 30 MHz acoustic waves is shown to be consistent and rapid, overcoming several limitations associated with its capillary-driven passive mixing counterpart wherein irreproducibilities and nonuniformities are often encountered in the mixing along the channel--capillary-driven passive mixing offers only poor control, is strongly dependent on the paper's texture and fibre alignment, and permits backflow, all due to the scale of the fibres being significant in comparison to the length scales of the features in a microfluidic system. Using a novel hue-based colourimetric technique, the mixing speed and efficiency is compared between the two methods, and used to assess the effects of changing the input power, channel tortuousity and fibre/flow alignment for the acoustically-driven mixing. The hue-based technique offers several advantages over grayscale pixel intensity analysis techniques in facilitating quantification without limitations on the colour contrast of the s les, and can be used, for ex le, for quantification in on-chip immunochromatographic assays.

Paper-Based Microfluidic Surface Acoustic Wave Sample Delivery and Ionization Source for Rapid and Sensitive Ambient Mass Spectrometry

Publisher: American Chemical Society (ACS)

Date: 07-04-2011

DOI: 10.1021/AC200380Q

Abstract: A surface acoustic wave-based s le delivery and ionization method that requires minimal to no s le pretreatment and that can operate under ambient conditions is described. This miniaturized technology enables real-time, rapid, and high-throughput analysis of trace compounds in complex mixtures, especially high ionic strength and viscous s les that can be challenging for conventional ionization techniques such as electrospray ionization. This technique takes advantage of high order surface acoustic wave (SAW) vibrations that both manipulate small volumes of liquid mixtures containing trace analyte compounds and seamlessly transfers analytes from the liquid s le into gas phase ions for mass spectrometry (MS) analysis. Drugs in human whole blood and plasma and heavy metals in tap water have been successfully detected at nanomolar concentrations by coupling a SAW atomization and ionization device with an inexpensive, paper-based s le delivery system and mass spectrometer. The miniaturized SAW ionization unit requires only a modest operating power of 3 to 4 W and, therefore, provides a viable and efficient ionization platform for the real-time analysis of a wide range of compounds.

A study on axial and torsional resonant mode matching for a mechanical system with complex nonlinear geometries

Publisher: AIP Publishing

Date: 06-2010

DOI: 10.1063/1.3430537

Abstract: Making use of mechanical resonance has many benefits for the design of microscale devices. A key to successfully incorporating this phenomenon in the design of a device is to understand how the resonant frequencies of interest are affected by changes to the geometric parameters of the design. For simple geometric shapes, this is quite easy, but for complex nonlinear designs, it becomes significantly more complex. In this paper, two novel modeling techniques are demonstrated to extract the axial and torsional resonant frequencies of a complex nonlinear geometry. The first decomposes the complex geometry into easy to model components, while the second uses scaling techniques combined with the finite element method. Both models overcome problems associated with using current analytical methods as design tools, and enable a full investigation of how changes in the geometric parameters affect the resonant frequencies of interest. The benefit of such models is then demonstrated through their use in the design of a prototype piezoelectric ultrasonic resonant micromotor which has improved performance characteristics over previous prototypes.

Fluid-structure interaction in deformable microchannels

Publisher: AIP Publishing

Date: 10-2012

DOI: 10.1063/1.4759493

Abstract: A polydimethylsiloxane microfluidic device composed of a single microchannel with a thin flexible layer present over a short length along one side of the channel was fabricated and modelled in order to investigate the complex fluid-structure interaction that arises between a flowing fluid and a deformable wall. Experimental measurements of thin layer deformation and pressure drop are compared with predictions of two- and three-dimensional computational models that numerically solve the coupled set of equations governing both the elasticity of the thin layer and the fluid. It is shown that the two-dimensional model, which assumes the flexible thin layer comprises an infinitely wide elastic beam of finite thickness, reasonably approximates a three-dimensional model, and is in excellent agreement with experimental observations of the thin layer profile when the width of the thin layer is beyond a critical value, roughly twice the length of the thin layer.

Capillary wave motion excited by high frequency surface acoustic waves

Publisher: AIP Publishing

Date: 11-2010

DOI: 10.1063/1.3505044

Abstract: This paper presents a numerical and experimental study of capillary wave motion excited by high frequency surface acoustic waves (SAWs). The objective of this study is to provide insight into the dynamic behavior of the fluid free surface and its dependence on the excitation litude. A two-dimensional numerical model that couples the motion of the piezoelectric substrate to a thin liquid layer atop the substrate is constructed. A perturbation method, in the limit of small- litude acoustic waves, is used to decompose the equations governing fluid motion to resolve the widely differing time scales associated with the high frequency excitation. While this model focuses on the free surface dynamics in the low- litude flow regime, the experimental study focuses on the high- litude flow regime. Transformation of time series data from both experiments and simulations into the frequency domain reveals that, in the low- litude regime, a fundamental resonant frequency and a superharmonic frequency are found in the frequency spectra. The former is found to be identical to that of the applied SAW, and the free surface displacement magnitude is comparable to that of the substrate displacement. Our numerical results also confirm previous speculation that the separation distance between two displacement antinodal points on the free surface is δSt≈λSAW/2 for a film and δSt≈λf/2 for a drop, where λSAW and λf denote the SAW wavelength and the acoustic wavelength in the fluid, respectively. Finally, in the high- litude regime, strong nonlinearities shift the acoustic energy to a lower frequency than that of the SAW this low-frequency broadband response, quite contrary to the subharmonic half-frequency capillary wave excitation predicted by the classical linear or weakly nonlinear Faraday theories, is supported by a scaling analysis of the momentum equations.

Fast inertial microfluidic actuation and manipulation using surface acoustic waves

Publisher: ASMEDC

Date: 2010

DOI: 10.1115/FEDSM-ICNMM2010-30181

Abstract: Though uncommon in most microfluidic systems due to the dominance of viscous and capillary stresses, it is possible to drive microscale fluid flows with considerable inertia using surface acoustic waves (SAWs), which are nanometer order litude electro-elastic waves that can be generated on a piezoelectric substrate. Due to the confinement of the acoustic energy to a thin localized region along the substrate surface and its subsequent leakage into the body of liquid with which the substrate comes into contact, SAWs are an extremely efficient mechanism for driving fast microfluidics. We demonstrate that it is possible to generate a variety of efficient microfluidic flows using the SAW. For ex le, the SAWs can be exploited to pump liquids in microchannels or to translate free droplets typically one or two orders of magnitude faster than conventional electroosmotic or electrowetting technology. In addition, it is possible to drive strong microcentrifugation for micromixing and bioparticle concentration or separation. In the latter, rich and complex colloidal pattern formation dynamics have also been observed. At large input powers, the SAW is a powerful means for the generation of jets and atomized aerosol droplets through rapid destabilization of the parent drop interface. In the former, slender liquid jets that persist up to centimeters in length can be generated without requiring nozzles or orifices. In the latter, a monodispersed distribution of 1–10 micron diameter aerosol droplets is obtained, which can be exploited for drug delivery and encapsulation, nanoparticle synthesis, and template-free polymer array patterning.

Surface acoustic waves: A new paradigm for driving ultrafast biomicrofluidics

Publisher: ASMEDC

Date: 2010

DOI: 10.1115/MNHMT2009-18517

Abstract: Surface acoustic waves (SAWs), which are 10 MHz order surface waves roughly 10 nm in litude propagating on the surface of a piezoelectric substrate, can offer a powerful method for driving fast microfluidic actuation and microparticle or biomolecule manipulation. We demonstrate that sessile drops can be linearly translated on planar substrates or fluid can be pumped through microchannels at typically one to two orders of magnitude faster than that achievable through current microfluidic technologies. Micromixing can be induced in the same microchannel in which fluid is pumped using the SAW simply by changing the SAW frequency to superimpose a chaotic oscillatory flow onto the uniform through flow. Strong inertial microcentrifugation for micromixing and particle concentration or separation can also be induced via symmetry-breaking. At low SAW litudes below that at which flow commences, the transverse standing wave that arises across the microchannel afford particle aggregation and hence sorting on nodal lines. Other microfluidic manipulations are also possible with the SAW. For ex le, capillary waves excited on a sessile drop by the SAW can be exploited for microparticle or nanoparticle collection and sorting. At higher litudes, the large substrate accelerations drives rapid destabilization of the drop interface giving rise to inertial liquid jets or atomization to produce 1–10 μm monodispersed aerosol droplets. These have significant implications for microfluidic chip mass spectrometry interfacing or pulmonary drug delivery. The atomization also provides a convenient means for the synthesis of 150–200 nm polymer or protein particles or to encapsulate proteins, peptides and other therapeutic molecules within biodegradable polymeric shells for controlled release drug delivery. The atomization of thin films containing polymer solutions, in addition, gives produces a unique regular, long-range spatial polymer spot patterning effect whose size and spacing are dependent on the SAW frequency, thus offering a simple and powerful method for surface patterning without requiring physical or chemical templating.

A piezoelectric ultrasonic linear micromotor using a slotted stator

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 08-2010

DOI: 10.1109/TUFFC.2010.1626

Surface acoustic streaming in microfluidic system for rapid multicellular tumor spheroids generation

Publisher: SPIE

Date: 07-12-2013

DOI: 10.1117/12.2034050

Double flow reversal in thin liquid films driven by megahertz-order surface vibration

Publisher: The Royal Society

Date: 08-09-2014

DOI: 10.1098/RSPA.2013.0765

Abstract: Arising from an interplay between capillary, acoustic and intermolecular forces, surface acoustic waves (SAWs) are observed to drive a unique and curious double flow reversal in the spreading of thin films. With a thickness at or less than the submicrometre viscous penetration depth, the film is seen to advance along the SAW propagation direction, and self-similarly over time t 1/4 in the inertial limit. At intermediate film thicknesses, beyond one-fourth the sound wavelength λ ℓ in the liquid, the spreading direction reverses, and the film propagates against the direction of the SAW propagation. The film reverses yet again, once its depth is further increased beyond one SAW wavelength. An unstable thickness region, between λ ℓ /8 and λ ℓ /4, exists from which regions of the film either rapidly grow in thickness to exceed λ ℓ /4 and move against the SAW propagation, consistent with the intermediate thickness films, whereas other regions decrease in thickness below λ ℓ /8 to conserve mass and move along the SAW propagation direction, consistent with the thin submicrometre films.

Miniaturised acoustofluidic tactile haptic actuator

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C9SM00479C

Abstract: Coupling the vibration from a piezoelectric substrate through a liquid microchamber facilitates the deflection of a membrane atop the liquid with sufficiently large deformation to facilitate static and dynamic tactile haptic feedback within a human detectable range.

Investigation of SAW atomization

Publisher: IEEE

Date: 09-2009

DOI: 10.1109/ULTSYM.2009.5441556

Extensional viscosity of copper nanowire suspensions in an aqueous polymer solution

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C5SM01940K

Abstract: Novel microfluidic experiments enabled the measurement of extensional viscosities of copper nanowire suspensions and their complex buffer, whose characterisation is essential for the development of advanced inkjet applications.

Unraveling interfacial jetting phenomena induced by focused surface acoustic waves

Publisher: IEEE

Date: 09-2009

DOI: 10.1109/ULTSYM.2009.5441559

Dynamics of liquid films exposed to high-frequency surface vibration

Publisher: American Physical Society (APS)

Date: 19-05-2015

DOI: 10.1103/PHYSREVE.91.053015

Editorial: Moving on in biomicrofluidics

Publisher: AIP Publishing

Date: 2013

DOI: 10.1063/1.4775344

Piezoelectric ultrasonic bidirectional linear actuator for micropositioning fulfilling Feynman's criteria

Publisher: AIP Publishing

Date: 07-01-2008

DOI: 10.1063/1.2814044

Abstract: A bidirectional linear microactuator with a stator less than 400μm3, fulfilling Feynman’s original criteria for a motor less than 1∕64th of an inch on a side [R. Feynman, Engineering and Science Magazine (Caltech) 4, 23 (1960)], is shown to generate forces over 30mN in either direction at speeds of up to 40mm∕s using a large 28g polished alumina slider. Using the thickness mode of a stepped piezoelectric block in conjunction with a pair of fundamental flexural modes of a pair of slanted beams—each slightly differs in configuration—gives the ability to generate silent bidirectional motion at an excitation frequency of about 1.7MHz. In addition to offering forces at least one order of magnitude larger than those of the other methods, the system also serves as a platform for studying nonlinear frictional phenomena on the nanoscale and its manipulation through acoustic irradiation of the contact interface for propulsion.

Microfluidic colloidal island formation and erasure induced by surface acoustic wave radiation

Publisher: American Physical Society (APS)

Date: 22-08-2008

DOI: 10.1103/PHYSREVLETT.101.084502

Planar microfluidic drop splitting and merging

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C4LC01453G

Abstract: Open droplet microfluidic platforms offer attractive alternatives to closed microchannel devices, including lower fabrication cost and complexity, significantly smaller s le and reagent volumes, reduced surface contact and adsorption, as well as drop scalability, reconfigurability, and in idual addressability.

Template-free Synthesis and Encapsulation Technique for Layer-by-Layer Polymer Nanocarrier Fabrication

Publisher: American Chemical Society (ACS)

Date: 15-11-2011

DOI: 10.1021/NN202833N

Abstract: The encapsulation of therapeutic molecules within multiple layers of biocompatible and biodegradable polymeric excipients allows exquisite design of their release profile, to the extent the drug can be selectively delivered to a specific target location in vivo. Here, we develop a novel technique for the assembly of multilayer polyelectrolyte nanocarriers based on surface acoustic wave atomization as a rapid and efficient alternative to conventional layer-by-layer assembly, which requires the use of a sacrificial colloidal template over which consecutive polyelectrolyte layers are deposited. Polymer nanocarriers are synthesized by atomizing a polymer solution and suspending them within a complementary polymer solution of opposite charge subsequent to their solidification in-flight as the solvent evaporates reatomizing this suspension produces nanocarriers with a layer of the second polymer deposited over the initial polymer core. Successive atomization-suspension layering steps can then be repeated to produce as many additional layers as desired. Specifically, we synthesize nanocarriers comprising two and three, and up to eight, alternating layers of chitosan (or polyethyleneimine) and carboxymethyl cellulose within which plasmid DNA is encapsulated and show in vitro DNA release profiles over several days. Evidence that the plasmid's viability is preserved and hence the potential of the technique for gene delivery is illustrated through efficient in vitro transfection of the encapsulated plasmid in human mesenchymal progenitor and COS-7 cells.

Triple Degree-of-Freedom Piezoelectric Ultrasonic Micromotor via Flexural-Axial

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 08-2009

DOI: 10.1109/TUFFC.2009.1236

Electric tempest in a teacup: The tea leaf analogy to microfluidic blood plasma separation

Publisher: AIP Publishing

Date: 04-09-2006

DOI: 10.1063/1.2345590

Abstract: In a similar fashion to Einstein’s tea leaf paradox, the rotational liquid flow induced by ionic wind above a liquid surface can trap suspended microparticles by a helical motion, spinning them down towards a bottom stagnation point. The motion is similar to Batchelor [Q. J. Mech. Appl. Math. 4, 29 (1951)] flows occurring between stationary and rotating disks and arises due to a combination of the primary azimuthal and secondary bulk meridional recirculation that produces a centrifugal and enhanced inward radial force near the chamber bottom. The technology is thus useful for microfluidic particle trapping/concentration the authors demonstrate its potential for rapid erythrocyte/blood plasma separation for miniaturized medical diagnostic kits.

Liquid Phase Acoustic Wave Exfoliation of Layered MoS2: Critical Impact of Electric Field in Efficiency

Publisher: American Chemical Society (ACS)

Date: 20-07-2018

DOI: 10.1021/ACS.CHEMMATER.8B01506

Arbitrary axis rotating surface acoustic wave micro motor

Publisher: IEEE

Date: 02-2011

DOI: 10.1109/NEMS.2011.6017324

Short‐Duration High Frequency MegaHertz‐Order Nanomechanostimulation Drives Early and Persistent Osteogenic Differentiation in Mesenchymal Stem Cells

Publisher: Wiley

Date: 13-01-2022

DOI: 10.1002/SMLL.202106823

Abstract: Stem cell fate can be directed through the application of various external physical stimuli, enabling a controlled approach to targeted differentiation. Studies involving the use of dynamic mechanical cues driven by vibrational excitation to date have, however, been limited to low frequency (Hz to kHz) forcing over extended durations (typically continuous treatment for days). Contrary to previous assertions that there is little benefit in applying frequencies beyond 1 kHz, we show here that high frequency MHz‐order mechanostimulation in the form of nanoscale litude surface reflected bulk waves are capable of triggering differentiation of human mesenchymal stem cells from various donor sources toward an osteoblast lineage, with early, short time stimuli inducing long‐term osteogenic commitment. More specifically, rapid treatments (10 min daily over 5 days) of the high frequency (10 MHz) mechanostimulation are shown to trigger significant upregulation in early osteogenic markers (RUNX2, COL1A1) and sustained increase in late markers (osteocalcin, osteopontin) through a mechanistic pathway involving piezo channel activation and Rho‐associated protein kinase signaling. Given the miniaturizability and low cost of the devices, the possibility for upscaling the platform toward practical bioreactors, to address a pressing need for more efficient stem cell differentiation technologies in the pursuit of translatable regenerative medicine strategies, is ensivaged.

Microfluidic chip containing porous gradient for chemotaxis study

Publisher: SPIE

Date: 21-12-2011

DOI: 10.1117/12.904870

Acoustopipetting: Tunable Nanoliter Sample Dispensing Using Surface Acoustic Waves

Publisher: American Chemical Society (ACS)

Date: 27-03-2019

DOI: 10.1021/ACS.ANALCHEM.8B05319

Abstract: We seek to demonstrate a robust, low-cost, and user-friendly acoustomicrofluidic platform that facilitates rapid, reproducible, and precise nanoliter s le dispensing. The solid-state chipscale platform exploits the unprecedented acceleration arising from high-frequency nanoelectromechanical vibrations, on the order of 10 million g, to jet the s le and hence generate a liquid bridge that spans across the substrate, on which the vibrations are generated and from which the s le originates, to a top target plate before rapidly pinching off to deposit the s le on the target with precise and reproducible volumes that can be tuned down to 0.22 μL with a standard error of 6.5% and coefficient of variation of 11.3%. The entire process occurs within approximately 10 ms. In addition to explicating the fundamental physical mechanism that underpins the technology, we demonstrate its use for serial dilution and concentration and, in particular, a cell-based drug toxicology assay. Moreover, we also show that multiple drop dispensing in an array, without requiring repositioning of the chip between dispensing steps, can be achieved through a simple but yet effective sequential directional jetting strategy, therefore allowing significant reduction in the total dispensing time in the case of massive-scale microarray operation. Given its low cost and compact size, the platform can easily be automated and parallelized, thus offering the prospect for introducing large-scale efficiencies in the laboratory workflow.

Graphene-mediated microfluidic transport and nebulization via high frequency Rayleigh wave substrate excitation

Publisher: Royal Society of Chemistry (RSC)

Date: 2016

DOI: 10.1039/C6LC00780E

Abstract: The addition of a graphene film onto a SAW device is shown to be a simple yet effective way to extract additional efficiency gains that can be exploited for a variety of on-chip microfluidic operations.

Atomization off thin water films generated by high-frequency substrate wave vibrations

Publisher: American Physical Society (APS)

Date: 20-11-2012

DOI: 10.1103/PHYSREVE.86.056312

Rotating bouncing disks, tossing pizza dough, and the behavior of ultrasonic motors

Publisher: American Physical Society (APS)

Date: 10-2009

DOI: 10.1103/PHYSREVE.80.046201

Pulmonary monoclonal antibody delivery via a portable microfluidic nebulization platform

Publisher: AIP Publishing

Date: 08-04-2015

DOI: 10.1063/1.4917181

Abstract: Nebulizers have considerable advantages over conventional inhalers for pulmonary drug administration, particularly because they do not require coordinated breath actuation to generate and deliver the aerosols. Nevertheless, besides being less amenable to miniaturization and hence portability, some nebulizers are prone to denature macromolecular drugs due to the large forces generated during aerosolization. Here, we demonstrate a novel portable acoustomicrofluidic device capable of nebulizing epidermal growth factor receptor (EGFR) monoclonal antibodies into a fine aerosol mist with a mass median aerodynamic diameter of approximately 1.1 μm, optimal for deep lung deposition via inhalation. The nebulized monoclonal antibodies were tested for their stability, immunoactivity, and pharmacological properties, which confirmed that nebulization did not cause significant degradation of the antibody. In particular, flow cytometry demonstrated that the antigen binding capability of the antibody is retained and able to reduce phosphorylation in cells overexpressing the EGFR, indicating that the aerosols generated by the device were loaded with stable and active monoclonal antibodies. The delivery of antibodies via inhalation, particularly for the treatment of lung cancer, is thus expected to enhance the efficacy of this protein therapeutic by increasing the local concentration where they are needed.

Acoustofluidic semen analysis for veterinary male bovine infertility assessment

Publisher: Cambridge University Press (CUP)

Date: 2023

DOI: 10.1017/FLO.2022.30

Abstract: We demonstrate through the use of a unique acoustically driven microfluidic extensional rheometry platform (ADMiER) that a single measurement – i.e. the time required for a liquid bridge filament comprising a microlitre semen s le to thin and break up under elastocapillary stresses – constitutes an appropriate proxy for quantifying the motile sperm concentration of the s le in place of computer-assisted sperm analysis (CASA) and haemocytometer measurements used in conventional semen assessment – without the need to separately resolve for in idual dependencies on each sperm parameter. By benchmarking diagnostic test accuracy results of blind random bull semen s les ( $n=35$ ) against OpenCASA measurements of these parameters, ADMiER is capable of predicting sperm quality to 93.7 % accuracy, 91.4 % sensitivity and 97.5 % specificity, with respect to commonly adopted veterinary industry minimum values for fertility. These results therefore highlight the potential diagnostic capability of the platform as a conceptual first step towards the development of a rapid, low-cost and portable alternative for veterinary male bovine fertility assessment.

Inducing rapid fluid flows in microchannels with surface acoustic waves

Publisher: IEEE

Date: 09-2009

DOI: 10.1109/ULTSYM.2009.5441547

Frequency effects on the scale and behavior of acoustic streaming

Publisher: American Physical Society (APS)

Date: 21-01-2014

DOI: 10.1103/PHYSREVE.89.013203

Interfacial destabilization and atomization driven by surface acoustic waves

Publisher: AIP Publishing

Date: 07-2008

DOI: 10.1063/1.2953537

Abstract: Surface acoustic wave atomization is a rapid means for generating micron and submicron aerosol droplets. Little, however, is understood about the mechanisms by which these droplets form due to the complex hydrodynamic processes that occur across widely varying length and time scales. Through experiments, scaling theory, and simple numerical modeling, we elucidate the interfacial destabilization mechanisms that lead to droplet formation. Using a millimeter-order fluid drop exposed to surface acoustic waves as it sits atop a single-crystal lithium niobate piezoelectric substrate, large aerosol droplets on the length scale of the parent drop dimension are ejected through a whipping and pinch-off phenomenon, which occurs at the asymmetrically formed crest of the drop due to leakage of acoustic radiation at the Rayleigh angle. Smaller micron order droplets, on the other hand, are formed due to the axisymmetric breakup of cylindrical liquid jets that are ejected as a consequence of interfacial destabilization. The 10μm droplet dimension correlates with the jet radius and the instability wavelength, both determined from a simple scaling argument involving a viscous-capillary dominant force balance. The results are further supported by numerical solution of the evolution equation governing the interfacial profile of a sessile drop along which an acoustic pressure wave is imposed. Viscous and capillary forces dominate in the bulk of the parent drop, but inertia is dominant in the ejected jets and within a thin boundary layer adjacent to the substrate where surface and interfacial accelerations are large. With the specific exception of parent drops that spread into thin films with thicknesses on the order of the boundary layer dimension prior to atomization, the free surface of the drop is always observed to vibrate at the capillary-viscous resonance frequency—even if the exciting frequency of the surface acoustic wave is several orders of magnitude larger—contrary to common assumptions used in deriving subharmonic models resulting in a Mathieu equation for the capillary wave motion, which has commonly led to erroneous predictions of the droplet size.

Monolithic Phononic Crystals with a Surface Acoustic Band Gap from Surface Phonon-Polariton Coupling

Publisher: American Physical Society (APS)

Date: 21-11-2014

DOI: 10.1103/PHYSREVLETT.113.215503

A scaffold cell seeding method driven by surface acoustic waves

Publisher: Elsevier BV

Date: 10-2007

DOI: 10.1016/J.BIOMATERIALS.2007.06.005

Abstract: Surface acoustic waves (SAW) have been employed to drive a particle suspension into a porous scaffold as a means for cell seeding. Straight, simple interdigital electrode structures were fabricated on lithium niobate to permit the generation of Rayleigh SAW radiation. Fluorescent microscopy was used to investigate the seeding process the SAW-driven seeding process occurred in approximately 10s, much quicker than if the scaffold were to be seeded by gravity-driven diffusional processes alone (>30min). Analysis of high-speed micrographic images demonstrated that the SAW method could also drive particles deeper into the scaffold, thereby significantly improving the uniformity of the particle distribution. The proposed SAW technique therefore offers a promising technology to dramatically improve the speed and uniformity of cell seeding in scaffolds, which might contribute to rapid and uniform tissue regeneration.

Inhaled pulmonary drug delivery platform using surface acoustic wave atomization

Publisher: ASMEDC

Date: 2010

DOI: 10.1115/MNHMT2009-18516

Abstract: Atomization has been widely applied in pulmonary drug delivery as a promising technology to transport drug formulations directly to the respiratory tract in the form of inhaled particles or droplets. Because of the targeted treatment, the drug can be delivered directly to the site of inflammation, thus the need for systemic exposure and the possibility of side effects are both reduced. Therefore pulmonary drug delivery has significant advantages over other methods in the treatment of respiratory diseases such as asthma. The most common atomization methods employed in pulmonary drug delivery are jet atomization and ultrasonic atomization. However, the difficulty is in producing monodispersed particles/droplets in a size range of 1–5 micron meter in diameter, necessary for deposition in the targeted lung area or lower respiratory airways, within a controllable fashion. In this paper, we demonstrate surface acoustic wave (SAW) atomization as an efficient technique to generate monodispersed aerosol to produce the required size distribution. The SAW atomizer is made of a 127.86 Y-X rotated single-crystal lithium niobate piezoelectric substrate, which is patterned with chromium-aluminum interdigital transducer (IDT) electrodes via UV lithography. When an alternating electric field is applied onto lithium niobate substrate through the IDT, a SAW, propagating across substrate surface with ten nanometer order litudes, is generated. When the SAW meets the liquid which is placed upon substrate, the acoustic energy carried by the wave induces atomization of the working fluid, which contains salbutamol as a model drug. In order to measure the size distribution of the atomized droplets, two methods are used. One is the laser diffraction based Spraytec technique and the other is an in-vitro lung modelthe one stage glass twin impinger. The former revealed that the mean diameter of the aerosol atomized was around 3 um which were confirmed by the lung model that demonstrated that nearly 80% of atomized drug aerosol was deposited in the simulated lung area. Moreover, the SAW atomizer only requires 1–3 W driving power, suggesting that it can be miniaturized for portable consumer use.

An ultrasonic piezoelectric motor utilizing axial-torsional coupling in a pretwisted non-circular cross-sectioned prismatic beam

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 04-2008

DOI: 10.1109/TUFFC.2008.717

Microscale anechoic architecture: Acoustic diffusers for ultra low power microparticle separation via traveling surface acoustic waves

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C4LC00704B

Abstract: A versatile, low-power traveling wave SAW microfluidic sorting device using a Schröder diffuser, adopted from its typical use in concert halls to the microscale.

Acoustomicrofluidic Defect Engineering and Ligand Exchange in ZIF‐8 Metal–Organic Frameworks

Publisher: Wiley

Date: 28-02-2023

DOI: 10.1002/SMTD.202201170

Abstract: A way through which the properties of metal–organic frameworks (MOFs) can be tuned is by engineering defects into the crystal structure. Given its intrinsic stability and rigidity, however, it is difficult to introduce defects into zeolitic imidazolate frameworks (ZIFs)—and ZIF‐8, in particular—without compromising crystal integrity. In this work, it is shown that the acoustic radiation pressure as well as the hydrodynamic stresses arising from the oscillatory flow generated by coupling high frequency (MHz‐order) hybrid surface and bulk acoustic waves into a suspension of ZIF‐8 crystals in a liquid pressure transmitting medium is capable of driving permanent structural changes in their crystal lattice structure. Over time, the enhancement in the diffusive transport of guest molecules into the material's pores as a consequence is shown to lead to expansion of the pore framework, and subsequently, the creation of dangling‐linker and missing‐linker defects, therefore offering the possibility of tuning the type and extent of defects engineered into the MOF through the acoustic exposure time. Additionally, the practical utility of the technology is demonstrated for one‐pot, simultaneous solvent‐assisted ligand exchange under ambient conditions, for sub‐micron‐dimension ZIF‐8 crystals and relatively large ligands—more specifically 2‐aminobenzimidazole—without compromising the framework porosity or overall crystal structure.

Submicron Particle and Cell Concentration in a Closed Chamber Surface Acoustic Wave Microcentrifuge

Publisher: American Chemical Society (ACS)

Date: 06-2020

DOI: 10.1021/ACS.ANALCHEM.0C01757

Enhancing greywater treatment via MHz-Order surface acoustic waves

Publisher: Elsevier BV

Date: 02-2020

DOI: 10.1016/J.WATRES.2019.115187

Abstract: There is a pressing need for efficient biological treatment systems for the removal of organic compounds in greywater given the rapid increase in household wastewater produced as a consequence of rapid urbanisation. Moreover, proper treatment of greywater allows its reuse that can significantly reduce the demand for freshwater supplies. Herein, we demonstrate the possibility of enhancing the removal efficiency of solid contaminants from greywater using MHz-order surface acoustic waves (SAWs). A key distinction of the use of these high frequency surface acoustic waves, compared to previous work on its lower frequency (kHz order) bulk ultrasound counterpart for wastewater treatment, is the absence of cavitation, which can inflict considerable damage on bacteria, thus limiting the intensity and duration, and hence the efficiency enhancement, associated with the acoustic exposure. In particular, we show that up to fivefold improvement in the removal efficiency can be obtained, primarily due to the ability of the acoustic pressure field in homogenizing and reducing the size of bacterial clusters in the s le, therefore providing a larger surface area that promotes greater bacteria digestion. Alternatively, the SAW exposure allows the reduction in the treatment duration to achieve a given level of removal efficiency, thus facilitating higher treatment rates and hence processing throughput. Given the low-cost of the miniature chipscale platform, these promising results highlight its possibility for portable greywater treatment for domestic use or for large-scale industrial wastewater processing through massive parallelization.

Concentration and mixing of particles in microdrops driven by focused surface acoustic waves

Publisher: IEEE

Date: 11-2008

DOI: 10.1109/ULTSYM.2008.0224

Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C4SM02742F

Abstract: Cell suspensions are model systems for studying properties of living materials. A comparison of theory against microfluidic experiments confirms that particle motility causes extensional viscosity to decrease in “pushers” and increase in “pushers”.

Substrate dependent drop deformation and wetting under high frequency vibration

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1SM06054F

Programmable Phototaxis of Metal–Phenolic Particle Microswimmers

Publisher: Wiley

Date: 26-02-2202

DOI: 10.1002/ADMA.202006177

Enhanced Antimicrobial Activity and Low Phytotoxicity of Acoustically Synthesized Large Aspect Ratio Cu-BTC Metal-Organic Frameworks with Exposed Metal Sites

Publisher: American Chemical Society (ACS)

Date: 02-12-2021

DOI: 10.1021/ACSAMI.1C16479

Editorial: A note from the new Co-Editor

Publisher: AIP Publishing

Date: 08-05-2009

DOI: 10.1063/1.3138046

Frequency bandwidth limitation of external pulse electric fields in cylindrical micro-channel electrophoresis with analyte velocity modulation

Publisher: Elsevier BV

Date: 04-2005

DOI: 10.1016/J.BIOS.2004.08.014

Abstract: In capillary electrophoresis, effective optical signal quality improvement is obtained when high frequency (>100 Hz) external pulse fields modulate analyte velocities with synchronous lock-in detection. However, the pulse frequency is constrained under a critical value corresponding to the time required for the bulk viscous flow, which arises due to viscous momentum diffusion from the electro-osmotic slip in the Debye layer, to reach steady-state. By solving the momentum diffusion equation for transient bulk flow in the micro-channel, we show that this set-in time to steady-state and hence, the upper limit for the pulse frequency is dependent on the characteristic diffusion length scale and therefore the channel geometry for cylindrical capillaries, the set-in time is approximately one half of that for rectangular slot channels. From our estimation of the set-in time and hence the upper frequency modulation limit, we propose that the half width of planar channels does not exceed 100 microm and that the radii of cylindrical channels be limited to 140 microm such that there is a finite working bandwidth range above 100 Hz and below the upper limit in order for flicker noise to be effectively suppressed.

Enabling practical surface acoustic wave nebulizer drug delivery via amplitude modulation

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4LC00232F

Abstract: A practical, commercially viable microfluidic device relies upon the miniaturization and integration of all its components—including pumps, circuitry, and power supply—onto a chip-based platform.

Precise drop dispensation on superhydrophobic surfaces using acoustic nebulization

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3SM00016H

Acoustically Driven Micromixing: Effect of Transducer Geometry

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 08-2019

DOI: 10.1109/TUFFC.2019.2920683

A new ac electrospray mechanism by Maxwell-Wagner polarization and capillary resonance

Publisher: American Physical Society (APS)

Date: 04-2004

DOI: 10.1103/PHYSREVLETT.92.133902

Lamb to Rayleigh Wave Conversion on Superstrates as a Means to Facilitate Disposable Acoustomicrofluidic Applications.

Publisher: American Chemical Society (ACS)

Date: 10-09-2019

DOI: 10.1021/ACS.ANALCHEM.9B02850

Abstract: Rayleigh surface acoustic waves (SAWs) have been demonstrated as a powerful and effective means for driving a wide range of microfluidic actuation processes. Traditionally, SAWs have been generated on piezoelectric substrates, although the cost of the material and the electrode deposition process makes them less amenable as low-cost and disposable components. As such, a "razor-and-blades" model that couples the acoustic energy of the SAW on the piezoelectric substrate through a fluid coupling layer and into a low-cost and, hence, disposable silicon superstrate on which various microfluidic processes can be conducted has been proposed. Nevertheless, it was shown that only bulk vibration in the form of Lamb waves can be excited in the superstrate, which is considerably less efficient and flexible in terms of microfluidic functionality compared to its surface counterpart, that is, the SAW. Here, we reveal an extremely simple way that quite unexpectedly and rather nonintuitively allows SAWs to be generated on the superstrate-by coating the superstrate with a thin gold layer. In addition to verifying the existence of the SAW on the coated superstrate, we carry out finite-difference time domain numerical simulations that not only confirm the experimental observations but also facilitate an understanding of the surprising difference that the coating makes. Finally, we elucidate the various power-dependent particle concentration phenomena that can be carried out in a sessile droplet atop the superstrate and show the possibility for simply carrying out rapid and effective microcentrifugation-a process that is considerably more difficult with Lamb wave excitation on the superstrate.

Acoustically-driven thread-based tuneable gradient generators

Publisher: Royal Society of Chemistry (RSC)

Date: 2016

DOI: 10.1039/C5LC00937E

Abstract: Dynamically tuneable concentration gradients are demonstrated in a thread-based microfluidic network that can be embedded in a three-dimensional hydrogel construct to mimic in vivo tissue microenvironments.

A description of phase inversion behaviour in agitated liquid-liquid dispersions under the influence of the Marangoni effect

Publisher: Elsevier BV

Date: 09-2002

DOI: 10.1016/S0009-2509(02)00260-9

Surface acoustic wave concentration of particle and bioparticle suspensions

Publisher: Springer Science and Business Media LLC

Date: 26-05-2007

DOI: 10.1007/S10544-007-9058-2

Abstract: A rapid particle concentration method in a sessile droplet has been developed using asymmetric surface acoustic wave (SAW) propagation on a substrate upon which the droplet is placed. Due to the asymmetry in the SAW propagation, azimuthal bulk liquid recirculation (acoustic streaming) is generated. Once the local particle concentration is sufficiently high within a particular streamline of the acoustic streaming convective flow, shear-induced migration gives rise to an inward radial force that concentrates the particles at the centre of the droplet. In this paper, a SAW device consists of a 0.75-mm thick, 127.68 degrees Y-X-axis-rotated cut, X-propagating LiNbO3 for a substrate and an interdigital transducer electrode (IDT) with 25 straight finger pairs in a simple repeating pattern, 12 mm aperture, and a wavelength of lambda=440 microm was patterned on the substrate. The IDT was then driven with a sinusoidal signal at the resonance frequency f0 of 8.611 MHz. To investigate the effect of particle type and size on the concentration process, three types of particles were used in this study, including fluorescent particles (1 microm), polystyrene microspheres (3, 6, 20, 45 microm), and living yeast cells (10-20 microm). Different RF powers were applied ranging from 120 to 510 mW. The concentration processes occurs within 2 to 20 s, depending on the particle size, type and input radio frequency (RF) power, much faster than currently available particle concentration mechanisms due to the large convective velocities achieved using the SAW device. Moreover, this concentration method is efficient, concentrating the particles into an aggregate one-tenth the size of the original droplet. Most importantly, bioparticles can also be concentrated by this method we have verified that yeast cells are not lysed by the SAW radiation during concentration. By using the rapid concentration process described in this work, the breadth of applications and measurement sensitivity of SAW biosensor systems should be greatly enhanced.

Hydroxypropyl Cellulose Methacrylate as a Photo‐Patternable and Biodegradable Hybrid Paper Substrate for Cell Culture and Other Bioapplications

Publisher: Wiley

Date: 29-08-2013

DOI: 10.1002/ADHM.201300155

Abstract: In addition to the choice of appropriate material properties of the tissue construct to be used, such as its biocompatibility, biodegradability, cytocompatibility, and mechanical rigidity, the ability to incorporate microarchitectural patterns in the construct to mimic that found in the cellular microenvironment is an important consideration in tissue engineering and regenerative medicine. Both these issues are addressed by demonstrating a method for preparing biodegradable and photo-patternable constructs, where modified cellulose is cross-linked to form an insoluble structure in an aqueous environment. Specifically, hydroxypropyl cellulose (HPC) is rendered photocrosslinkable by grafting with methylacrylic anhydride, whose linkages also render the cross-linked construct hydrolytically degradable. The HPC is then cross-linked via a photolithography-based fabrication process. The feasibility of functionalizing these HPC structures with biochemical cues is verified post-fabrication, and shown to facilitate the adhesion of mesenchymal progenitor cells. The HPC constructs are shown to be biocompatible and hydrolytically degradable, thus enabling cell proliferation and cell migration, and therefore constituting an ideal candidate for long-term cell culture and implantable tissue scaffold applications. In addition, the potential of the HPC structure is demonstrated as an alternative substrate to paper microfluidic diagnostic devices for protein and cell assays.

Rapid production of protein-loaded biodegradable microparticles using surface acoustic waves

Publisher: AIP Publishing

Date: 03-2009

DOI: 10.1063/1.3055282

Piezoelectric ultrasonic micro/milli-scale actuators

Publisher: Elsevier BV

Date: 06-2009

DOI: 10.1016/J.SNA.2009.04.001

Preface to special topic: Papers from the 2009 conference on advances in microfluidics and nanofluidics, The Hong Kong University of Science & Technology, Hong Kong, 2009

Publisher: AIP Publishing

Date: 06-2009

DOI: 10.1063/1.3167278

Abstract: The inaugural conference on Advances in Microfluidics and Nanofluidics was held at the Hong Kong University of Science and Technology on 5–7 January 2009 and brought together leading researchers from across a wide variety of disciplines from North America, Europe, Asia, and Oceania. This Special Topic section forms the second of the two issues dedicated to original contributions covering both fundamental physicochemical aspects of microfluidics and nanofluidics as well as their applications to the miniaturization of chemical and biological systems that were presented at the conference.

Multi-degree-of-freedom ultrasonic micromotor for guidewire and catheter navigation: The NeuroGlide actuator

Publisher: AIP Publishing

Date: 16-04-2012

DOI: 10.1063/1.3702579

Abstract: A 240-μm diameter ultrasonic micromotor is presented as a potential solution for an especially difficult task in minimally invasive neurosurgery, navigating a guidewire to an injury in the neurovasculature as the first step of surgery. The peak no-load angular velocity and maximum torque were 600 rad/s and 1.6 nN-m, respectively, and we obtained rotation about all three axes. By using a burst drive scheme, open-loop position and speed control were achieved. The construction method and control scheme proposed in this study remove most of the current limitations in minimally invasive, catheter-based actuation, enabling minimally invasive vascular surgery concepts to be pursued for a broad variety of applications.

The appearance of boundary layers and drift flows due to high-frequency surface waves

Publisher: Cambridge University Press (CUP)

Date: 20-07-2012

DOI: 10.1017/JFM.2012.293

Abstract: The classical Schlichting boundary layer theory is extended to account for the excitation of generalized surface waves in the frequency and velocity litude range commonly used in microfluidic applications, including Rayleigh and Sezawa surface waves and Lamb, flexural and surface-skimming bulk waves. These waves possess longitudinal and transverse displacements of similar magnitude along the boundary, often spatiotemporally out of phase, giving rise to a periodic flow shown to consist of a superposition of classical Schlichting streaming and uniaxial flow that have no net influence on the flow over a long period of time. Correcting the velocity field for weak but significant inertial effects results in a non-vanishing steady component, a drift flow, itself sensitive to both the litude and phase (prograde or retrograde) of the surface acoustic wave propagating along the boundary. We validate the proposed theory with experimental observations of colloidal pattern assembly in microchannels filled with dilute particle suspensions to show the complexity of the boundary layer, and suggest an asymptotic slip boundary condition for bulk flow in microfluidic applications that are actuated by surface waves.

Recovery of oxidized two-dimensional MXenes through high frequency nanoscale electromechanical vibration

Publisher: Springer Science and Business Media LLC

Date: 03-01-2023

DOI: 10.1038/S41467-022-34699-3

Abstract: MXenes hold immense potential given their superior electrical properties. The practical adoption of these promising materials is, however, severely constrained by their oxidative susceptibility, leading to significant performance deterioration and lifespan limitations. Attempts to preserve MXenes have been limited, and it has not been possible thus far to reverse the material’s performance. In this work, we show that subjecting oxidized micron or nanometer thickness dry MXene films—even those constructed from nanometer-order solution-dispersed oxidized flakes—to just one minute of 10 MHz nanoscale electromechanical vibration leads to considerable removal of its surface oxide layer, whilst preserving its structure and characteristics. Importantly, electrochemical performance is recovered close to that of their original state: the pseudocapacitance, which decreased by almost 50% due to its oxidation, reverses to approximately 98% of its original value, with good capacitance retention ( ≈ 93%) following 10,000 charge–discharge cycles at 10 A g −1 . These promising results allude to the exciting possibility for rejuvenating the material for reuse, therefore offering a more economical and sustainable route that improves its potential for practical translation.

Rapid production of biocompatible polymeric nanoparticles for functionalization via radio-frequency acoustic atomization

Publisher: IEEE

Date: 08-2007

DOI: 10.1109/NANO.2007.4601130

AC electrospray biomaterials synthesis

Publisher: Elsevier BV

Date: 11-2005

DOI: 10.1016/J.BIOMATERIALS.2005.03.033

Abstract: A rapid, viable and safe fabrication method for biomaterials synthesis is reported using high-frequency AC electrospraying. We demonstrate its potential for polymeric nanoparticle fabrication, drug encapsulation in mono-dispersed micron-sized biodegradable polymer shells and the synthesis of 1microm biodegradable fibers with adjustable pore sizes as bioscaffolds for tissue/orthopaedic engineering and wound care therapy. The absence of charge in the ejected drops and fibers facilitates pulmonary drug delivery, polymer encapsulation and minimizes protein/DNA denaturing or compound ionization.

Acoustotemplating: rapid synthesis of freestanding quasi-2D MOF/graphene oxide heterostructures for supercapacitor applications

Publisher: Royal Society of Chemistry (RSC)

Date: 2022

DOI: 10.1039/D1TA10493D

Abstract: Quasi two-dimensional MOF/graphene oxide heterostructures are synthesized using a MHz frequency acoustotemplating method. The composite exhibits two-orders of magnitude higher supercapacitance compared to its 3D HKUST-1/graphene oxide counterpart.

A brief review of actuation at the micro-scale using electrostatics, electromagnetics and piezoelectric ultrasonics

Publisher: Acoustical Society of Japan

Date: 2010

DOI: 10.1250/AST.31.115

Free Radical Generation from High-Frequency Electromechanical Dissociation of Pure Water

Publisher: American Chemical Society (ACS)

Date: 26-05-2020

DOI: 10.1021/ACS.JPCLETT.0C01227

RF-activated standing surface acoustic wave for on-chip particle manipulation

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 09-2014

DOI: 10.1109/TMTT.2014.2342667

Double aperture focusing transducer for controlling microparticle motions in trapezoidal microchannels with surface acoustic waves

Publisher: AIP Publishing

Date: 28-09-2009

DOI: 10.1063/1.3238313

Abstract: We present a method for controlling the motion of microparticles suspended in an aqueous solution, which fills in a microchannel fabricated into a piezoelectric substrate, using propagating surface acoustic waves. The cross-sectional shape of this microchannel is trapezoidal, preventing the formation of acoustic standing waves across the channel width and therefore allowing the steering of microparticles. The induced acoustic streaming transports these particles to eliminate the use of external pumps for fluid actuation.

The dynamics of surface acoustic wave-driven scaffold cell seeding

Publisher: Wiley

Date: 06-2009

DOI: 10.1002/BIT.22243

Abstract: Flow visualization using fluorescent microparticles and cell viability investigations are carried out to examine the mechanisms by which cells are seeded into scaffolds driven by surface acoustic waves. The former consists of observing both the external flow prior to the entry of the suspension into the scaffold and the internal flow within the scaffold pores. The latter involves micro-CT (computed tomography) scans of the particle distributions within the seeded scaffolds and visual and quantitative methods to examine the morphology and proliferation ability of the irradiated cells. The results of these investigations elucidate the mechanisms by which particles are seeded, and hence provide valuable information that form the basis for optimizing this recently discovered method for rapid, efficient, and uniform scaffold cell seeding. Yeast cells are observed to maintain their size and morphology as well as their proliferation ability over 14 days after they are irradiated. The mammalian primary osteoblast cells tested also show little difference in their viability when exposed to the surface acoustic wave irradiation compared to a control set. Together, these provide initial feasibility results that demonstrate the surface acoustic wave technology as a viable seeding method without risk of denaturing the cells.

Rotational microfluidic motor for on-chip microcentrifugation

Publisher: AIP Publishing

Date: 20-06-2011

DOI: 10.1063/1.3600775

Abstract: We report on the design of a surface acoustic wave (SAW) driven fluid-coupled micromotor which runs at high rotational velocities. A pair of opposing SAWs generated on a lithium niobate substrate are each obliquely passed into either side of a fluid drop to drive rotation of the fluid, and the thin circular disk set on the drop. Using water for the drop, a 5 mm diameter disk was driven with rotation speeds and start-up torques up to 2250 rpm and 60 nN m, respectively. Most importantly for lab-on-a-chip applications, radial accelerations of 172 m/s2 was obtained, presenting possibilities for microcentrifugation, flow sequencing, assays, and cell culturing in truly microscale lab-on-a-chip devices.

Direct visualization of surface acoustic waves along substrates using smoke particles

Publisher: AIP Publishing

Date: 26-11-2007

DOI: 10.1063/1.2814054

Abstract: Smoke particles (SPs) are used to directly visualize surface acoustic waves (SAWs) propagating on a 128°-rotated Y-cut X-propagating lithium niobate (LiNbO3) substrate. By electrically exciting a SAW device in a compartment filled with SP, the SP were found to collect along the regions where the SAW propagates on the substrate. The results of the experiments show that SPs are deposited adjacent to regions of large vibration litude and form a clear pattern corresponding to the surface wave profile on the substrate. Through an analysis of the SAW-induced acoustic streaming in the air adjacent to the substrate and the surface acceleration measured with a laser Doppler vibrometer, we postulate that the large transverse surface accelerations due to the SAW ejects SP from the surface and carries them aloft to relatively quiescent regions nearby via acoustic streaming. Offering finer detail than fine powders common in Chladni figures [E. Chladni, Entdeckungen über die Theorie des Klanges (Weidmanns, Erben und Reich, Leipzig, Germany, 1787)] the approach is an inexpensive and a quick counterpart to laser interferometric techniques, presenting a means to explore the controversial phenomena of particle agglomeration on surfaces.

Quantification of surface acoustic wave induced chaotic mixing-flows in microfluidic wells

Publisher: Elsevier BV

Date: 12-2011

DOI: 10.1016/J.SNB.2011.09.007

Cassie–Wenzel wetting transition on nanostructured superhydrophobic surfaces induced by surface acoustic waves

Publisher: AIP Publishing

Date: 02-03-2020

DOI: 10.1063/1.5145282

Abstract: We report irreversible Cassie–Wenzel wetting transition on a nanostructured superhydrophobic surface employing surface acoustic wave (SAW) vibration. The transition is achieved upon penetration of the liquid into the nanogrooves driven by the inertial energy of the drop imparted by the SAW. However, the filling up of nanopores imposes an energy barrier (Eb) to the transition, which requires the displacement of the initial solid–air interface inside the pores with a solid–liquid interface. We unravel that the relative magnitudes of the input acoustic energy (Eac), and this energy barrier, hence, dictate the occurrence of the wetting transition, with the irreversibility in the transition, therefore, being explained from energy minimization of the system following the transition. In addition, observing the dynamics of the wetting front allowed the different regimes of the wetting transition process to be identified.

Ultrafast assembly of swordlike Cu₃(1,3,5-benzenetricarboxylate)_n metal–organic framework crystals with exposed active metal sites

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0NH00171F

Abstract: A new acoustomicrofluidic method for synthesizing copper-based metal–organic frameworks is shown to yield novel large aspect ratio elongated crystal morphologies with high active metal site density on their surfaces, leading to enhanced conductivity.

Interfacial Jetting Phenomena Induced by Focused Surface Vibrations

Publisher: American Physical Society (APS)

Date: 07-07-2009

DOI: 10.1103/PHYSREVLETT.103.024501

Static and spontaneous electrowetting

Publisher: World Scientific Pub Co Pte Lt

Date: 30-05-2005

DOI: 10.1142/S0217984905008542

Abstract: There has been recent renewed interest in electrocapillary and electrowetting phenomena given its potential for microfluidic actuation and manipulation. Different approaches, in which a variety of electrode configurations have been adopted, however, have dominated the developments in this field. These different approaches have given rise to rich and varied behavior, which has often led to some overlap and confusion in the literature. In this article, we delineate the different observations and elucidate the relationship between these phenomena by re-stressing classical concepts and examining their limitations. Particular emphasis is placed on the distinction between static and spontaneous electrowetting. In the former, a static change in the liquid–solid macroscopic contact angle results when a dielectric film-coated planar plate electrode is employed. In the latter, a spontaneous thin fron-t-running electrowetting film is pulled out ahead of the macroscopic drop with the use of planar parallel line electrodes. This dynamically evolving electrowetting film advances much faster than the macroscopic drop itself and behaves in a self-similar manner analogous to gravity spreading films.

A waveguide based microfluidic application

Publisher: SPIE

Date: 07-12-2013

DOI: 10.1117/12.2033743

Unique flow transitions and particle collection switching phenomena in a microchannel induced by surface acoustic waves

Publisher: AIP Publishing

Date: 06-12-2010

DOI: 10.1063/1.3524511

Abstract: We present an experimental approach for controlled switching between uniform flow for pumping and vortical flow for mixing in a microchannel fabricated onto a piezoelectric substrate. For particle laden fluids, this arrangement permits a choice between transport and alignment of microparticles. Using surface acoustic waves with litudes beyond 1 nm, the transition from uniform to mixing flows occurs when the acoustic wavelength in the fluid is reduced to a dimension smaller than the channel width, i.e., λf≥Wch for uniform flow and λf& Wch for mixing flow. On the other hand, using relatively weak surface acoustic waves with litudes below 1 nm, particles in an initially homogeneous suspension agglomerate into equally spaced lines with a separation of λf/2. Switching the transducer between its fundamental resonant frequency f0 and its first harmonic frequency f1+∼2f0 causes a switch between uniform and mixing flow, while switching between large and small litude excitation allows one to choose whether to collect the particles in the flow along nodal lines parallel to the channel. These results are uniquely achieved without requiring the microfabrication of complex microchannel architectures and control schemes the switching is simply achieved by adjusting two parameters: the acoustic excitation frequency and litude.

Emerging Technologies for Next-Generation Point-of-Care Testing

Publisher: Elsevier BV

Date: 11-2015

DOI: 10.1016/J.TIBTECH.2015.09.001

Abstract: Considerable advances in point-of-care testing (POCT) devices stem from innovations in cellphone (CP)-based technologies, paper-based assays (PBAs), lab-on-a-chip (LOC) platforms, novel assay formats, and strategies for long-term reagent storage. Various commercial CP platforms have emerged to provide cost-effective mobile health care and personalized medicine. Such assay formats, as well as low-cost PBAs and LOC-based assays, are paving the way to robust, automated, simplified, and cost-effective POCT. Strategies have also been devised to stabilize reagent storage and usage at ambient temperature. Nevertheless, successful commercialization and widespread implementation of such clinically viable technologies remain subject to several challenges and pending issues.

Continuous tuneable droplet ejection via pulsed surface acoustic wave jetting

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C7SM02534C

Abstract: A versatile acoustic chipscale platform that can potentially be mounted as a printhead for cell encapsulation, dispensing and 3D bioprinting.

Editorial: A new year and a new Associate Editor

Publisher: AIP Publishing

Date: 03-2011

DOI: 10.1063/1.3563606

The behavior of bouncing disks and pizza tossing

Publisher: IOP Publishing

Date: 03-2009

DOI: 10.1209/0295-5075/85/60002

Ultrafast microfluidics using surface acoustic waves

Publisher: AIP Publishing

Date: 03-2009

DOI: 10.1063/1.3056040

Surface acoustic wave microfluidics

Publisher: Annual Reviews

Date: 03-01-2014

DOI: 10.1146/ANNUREV-FLUID-010313-141418

Abstract: Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10–1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a erse range of complex fluid transport phenomena—from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization—underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

In Situ Generation of Tunable Porosity Gradients in Hydrogel‐Based Scaffolds for Microfluidic Cell Culture

Publisher: Wiley

Date: 07-04-2014

DOI: 10.1002/ADHM.201400072

Abstract: Compared with preformed anisotropic matrices, an anisotropic matrix that allows users to alter its properties and structure in situ after synthesis offers the important advantage of being able to mimic dynamic in vivo microenvironments, such as in tissues undergoing morphogenesis or in wounds undergoing tissue repair. In this study, porous gradients are generated in situ in a hydrogel comprising enzymatically crosslinked gelatin hydroxyphenylpropionic acid (GTN-HPA) conjugate and carboxylmethyl cellulose tyramine (CMC-TYR) conjugate. The GTN-HPA component acts as the backbone of the hydrogel, while CMC-TYR acts as a biocompatible sacrificial polymer. The hydrogel is then used to immobilize HT1080 human fibrosarcoma cells in a microfluidic chamber. After diffusion of a biocompatible cellulase enzyme through the hydrogel in a spatially controlled manner, selective digestion of the CMC component of the hydrogel by the cellulase gives rise to a porosity gradient in situ instead of requiring its formation during hydrogel synthesis as with other methods. The influence of this in situ tunable porosity gradient on the chemotactic response of cancer cells is subsequently studied both in the absence and presence of chemoattractant. This platform illustrates the potential of hydrogel-based microfluidics to mimic the 3D in vivo microenvironment for tissue engineering and diagnostic applications.

Microfluidic blood plasma separation via bulk electrohydrodynamic flows

Publisher: AIP Publishing

Date: 03-2007

DOI: 10.1063/1.2409629

Acoustofection: High-Frequency Vibrational Membrane Permeabilization for Intracellular siRNA Delivery into Nonadherent Cells

Publisher: American Chemical Society (ACS)

Date: 03-03-2021

DOI: 10.1021/ACSABM.1C00003

Abstract: The internalization of therapeutic molecules into cells-a critical step in enabling a suite of autologous ex vivo gene and cell therapies-is highly regulated by the lipid barrier imposed by the cell membrane. Strategies to increase the efficiency of delivering these exogenous payloads into the cell, while maintaining the integrity of both the therapeutic molecules to be delivered as well as the host cells they are delivered to, are therefore required. This is especially the case for suspension cells that are particularly difficult to transfect. In this work, we show that it is possible to enhance the uptake of short interfering RNA (siRNA) into nonadherent Jurkat and HuT 78 cells with a rapid poration-free method involving high-frequency (MHz order) acoustic excitation. The 2-fold enhancement in gene knockdown is almost comparable with that obtained with conventional nucleofection, which is among the most widely used intracellular delivery methods, but with considerably higher cell viabilities (>91% compared to approximately 76%) owing to the absence of pore formation. The rapid and effective delivery afforded by the platform, together with its low cost and scalability, therefore renders it a potent tool in the cell engineering pipeline.

Surface acoustic waves as an energy source for drop scale synthetic chemistry

Publisher: Royal Society of Chemistry (RSC)

Date: 2009

DOI: 10.1039/B819217K

Abstract: A new modality for chemical synthesis on a drop scale which employs a piezoelectric chip as the reactor and surface acoustic waves (SAWs) as the source of energy (and consequent heating) is described.

In situ generation of plasma-activated aerosols via surface acoustic wave nebulization for portable spray-based surface bacterial inactivation

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0LC00001A

Abstract: We demonstrate an efficient technique for in situ production and application of plasma-activated aerosols for surface disinfection.

Microparticle collection and concentration via a miniature surface acoustic wave device

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B618044B

Abstract: The ability to detect microbes, pollens and other microparticles is a critically important ability given the increasing risk of bioterrorism and emergence of antibiotic-resistant bacteria. The efficient collection of microparticles via a liquid water droplet moved by a surface acoustic wave (SAW) device is demonstrated in this study. A fluidic track patterned on the SAW device directs the water droplet's motion, and fluid streaming induced inside the droplet as it moves along is a key advantage over other particle collection approaches, because it enhances microparticle collection and concentration. Test particles consisted of 2, 10, 12 and 45 microm diameter monodisperse polystyrene and melamine microparticles pollen from the Populus deltoides, Kochia scoparia, Secale cerale, and Broussonetia papyrifera (Paper Mulberry) species and Escherichia coli bacteria. The collection efficiency for the synthetic particles ranged from 16 to 55%, depending on the particle size and surface tension of the collection fluid. The method was more effective in collecting pollen and the bacteria with an efficiency of 45-68% and 61.0-69.8%, respectively. Pollen collection was strongly influenced by its diameter, size, and surface geometry in a manner contrary to initial expectations. Reasons for the consistent yet unexpected collection results include leaky SAW pressure boundary segregation and shear-induced concentration of larger particles, and the subtle effects of wetting interactions. These results demonstrate a new method for collecting microparticles requiring only about one second per run, and illustrate the inadequacy of using synthetic microparticles as a substitute for their biological counterparts in experiments studying particle collection and behavior.

A miniaturized surface acoustic wave atomizer with a disposable pump-free liquid supply system for continuous atomization

Publisher: IEEE

Date: 02-2011

DOI: 10.1109/NEMS.2011.6017350

Focused ion beam milling of microchannels in lithium niobate

Publisher: AIP Publishing

Date: 03-2012

DOI: 10.1063/1.3673260

Abstract: We present experimental and simulation results for focused ion beam (FIB) milling of microchannels in lithium niobate in this paper. We investigate two different cuts of lithium niobate, Y- and Z-cuts, and observe that the experimental material removal rate in the FIB for both Y-cut and Z-cut s les was 0.3 μm3/nC, roughly two times greater than the material removal rate previously reported in the literature but in good agreement with the value we obtain from stopping and range of ions in matter (SRIM) simulations. Further, we investigate the FIB milling rate and resultant cross-sectional profile of microchannels at various ion beam currents and find that the milling rate decreases as a function of ion dose and correspondingly, the cross-sectional profiles change from rectangular to V-shaped. This indicates that material redeposition plays an important role at high ion dose or equivalently, high aspect ratio. We find that the experimental material removal rate decreases as a function of aspect ratio of the milled structures, in good agreement with our simulation results at low aspect ratio and in good agreement with the material removal rates previously reported in the literature at high aspect ratios. Our results show that it is indeed easier than previously assumed to fabricate nanochannels with low aspect ratio directly on lithium niobate using the FIB milling technique.

ADMiER-ing thin but complex fluids

Publisher: SPIE

Date: 21-12-2011

DOI: 10.1117/12.903238

Effect of surface acoustic waves on the viability, proliferation and differentiation of primary osteoblast-like cells

Publisher: AIP Publishing

Date: 09-2009

DOI: 10.1063/1.3194282

High frequency acoustic cell stimulation promotes exosome generation regulated by a calcium-dependent mechanism

Publisher: Springer Science and Business Media LLC

Date: 05-10-2020

DOI: 10.1038/S42003-020-01277-6

Abstract: Exosomes are promising disease diagnostic markers and drug delivery vehicles, although their use in practice is limited by insufficient homogeneous quantities that can be produced. We reveal that exposing cells to high frequency acoustic irradiation stimulates their generation without detriment to cell viability by exploiting their innate membrane repair mechanism, wherein the enhanced recruitment of calcium ions from the extracellular milieu into the cells triggers an ESCRT pathway known to orchestrate exosomal production. Given the high post-irradiation cell viabilities (≈95%), we are able to recycle the cells through iterative irradiation and post-excitation incubation steps, which facilitate high throughput production of a homogeneous population of exosomes—a particular challenge for translating exosome therapy into clinical practice. In particular, we show that approximately eight- to ten-fold enrichment in the number of exosomes produced can be achieved with just 7 cycles over 280 mins, equivalent to a yield of around 1.7–2.1-fold/h.

Acoustomicrofluidic synthesis of ZIF-8/HRP metal–organic framework composites with enhanced enzymatic activity and stability

Publisher: Elsevier BV

Date: 10-2023

DOI: 10.1016/J.MTCHEM.2023.101694

Unique fingering instabilities and soliton-like wave propagation in thin acoustowetting films

Publisher: Springer Science and Business Media LLC

Date: 06-11-2012

DOI: 10.1038/NCOMMS2168

Abstract: Acoustic-fluid interactions not only has had a long history but has recently experienced renewed scrutiny because of their vast potential for microscale fluid and particle manipulation. Here we unravel a fascinating and anomalous ensemble of dynamic 'acoustowetting' phenomena in which a thin film drawn from a sessile drop first spreads in opposition to the acoustic wave propagation direction. The advancing film front then exhibits fingering instabilities akin to classical viscous fingering, but arising through a different and novel mechanism: transverse Fresnel diffraction of the underlying acoustic wave. Peculiar 'soliton-like' wave pulses are observed to grow above these fingers, which, on reaching a critical size, translate away along the wave propagation direction. By elucidating the complex hydrodynamics underpinning the spreading, and associated flow reversal and instability phenomena, we offer insight into the possibility of acoustically controlling fast and uniform film spreading, constituting a flexible and powerful alternative for microfluidic transport.

Fast surface acoustic wave-matrix-assisted laser desorption ionization mass spectrometry of cell response from islets of langerhans

Publisher: American Chemical Society (ACS)

Date: 21-02-2013

DOI: 10.1021/AC3019125

Abstract: A desire for higher speed and performance in molecular profiling analysis at a reduced cost is driving a trend in miniaturization and simplification of procedures. Here we report the use of a surface acoustic wave (SAW) atomizer for fast s le handling in matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) peptide and protein profiling of Islets of Langerhans, for future type 2 diabetes (T2D) studies. Here the SAW atomizer was used for ultrasound (acoustic) extraction of insulin and other peptide hormones released from freshly prepared islets, stimulated directly on a membrane. A high energy propagating SAW atomizes the membrane-bound liquid into approximately 2 μm diameter droplets, rich in cell-released molecules. Besides acting as a s le carrier, the membrane provides a purification step by entrapping cell clusters and other impurities within its fibers. A new SAW-based s le-matrix deposition method for MALDI MS was developed and characterized by a strong insulin signal, and a limit of detection (LOD) lower than 100 amol was achieved. Our results support previous work reporting the SAW atomizer as a fast and inexpensive tool for ultrasound, membrane-based s le extraction. When interfaced with MALDI MS, the SAW atomizer constitutes a valuable tool for rapid cell studies. Other biomedical applications of SAW-MALDI MS are currently being developed, aiming at fast profiling of biofluids. The membrane s ling is a simplistic and noninvasive collection method of limited volume biofluids such as the gingival fluid and the tearfilm.

Nanoparticle patterning in a microfluidic drop induced by surface acoustic waves

Publisher: IEEE

Date: 09-2009

DOI: 10.1109/ULTSYM.2009.5441910

Increasing Exfoliation Yield in the Synthesis of MoS₂ Quantum Dots for Optoelectronic and Other Applications through a Continuous Multicycle Acoustomicrofluidic Approach

Publisher: American Chemical Society (ACS)

Date: 06-2018

DOI: 10.1021/ACSANM.8B00559

Miniaturized Lab‐on‐a‐Disc (miniLOAD)

Publisher: Wiley

Date: 10-04-2012

DOI: 10.1002/SMLL.201102282

Abstract: A miniaturized centrifugal microfluidic platform for lab-on-a-chip applications is presented. Unlike its macroscopic Lab-on-a-CD counterpart, the miniature Lab-on-a-Disc (miniLOAD) device does not require moving parts to drive rotation of the disc, is inexpensive, disposable, and significantly smaller, comprising a 10-mm-diameter SU-8 disc fabricated through two-step photolithography. The disc is driven to rotate using surface acoustic wave irradiation incident upon a fluid coupling layer from a pair of offset, opposing single-phase unidirectional transducers patterned on a lithium niobate substrate. The irradiation causes azimuthally oriented acoustic streaming with sufficient intensity to rotate the disc at several thousand revolutions per minute. In this first proof-of-concept, the capability of the miniLOAD platform to drive capillary-based valving and mixing in microfluidic structures on a disc similar to much larger Lab-on-a-CD devices is shown. In addition, the ability to concentrate aqueous particle suspensions at radial positions in a channel in the disc dependent on the particles' size is demonstrated. To the best of our knowledge, the miniLOAD concept is the first centrifugal microfluidic platform small enough to be self-contained in a handheld device.

Electrowetting films on parallel line electrodes

Publisher: American Physical Society (APS)

Date: 20-01-2006

DOI: 10.1103/PHYSREVE.73.011605

SAW atomization application on inhaled pulmonary drug delivery

Publisher: SPIE

Date: 26-12-2009

DOI: 10.1117/12.813983

Fast three-dimensional micropatterning of PC12 cells in rapidly crosslinked hydrogel scaffolds using ultrasonic standing waves

Publisher: IOP Publishing

Date: 02-12-2019

DOI: 10.1088/1758-5090/AB4CCA

Abstract: The ability to spatially organise the microenvironment of tissue scaffolds unlocks the potential of many scaffold-based tissue engineering applications. An ex le application is to aid the regeneration process of peripheral nerve injuries. Herein, we present a promising approach for three-dimensional (3D) micropatterning of nerve cells in tissue scaffolds for peripheral nerve repair. In particular, we demonstrate the 3D micropatterning of PC12 cells in a gelatin-hydroxyphenylpropionic acid (Gtn-HPA) hydrogel using ultrasound standing waves (USWs). PC12 cells were first aligned in 3D along nodal planes by the USWs in Gtn-HPA hydrogel precursor solution. The precursor was then crosslinked using horseradish peroxidase (HRP) and diluted hydrogen peroxide (H

Highly Ordered Arrays of Femtoliter Surface Droplets

Publisher: Wiley

Date: 14-07-2015

DOI: 10.1002/SMLL.201501105

Acoustomicrofluidic assembly of oriented and simultaneously activated metal–organic frameworks

Publisher: Springer Science and Business Media LLC

Date: 23-05-2019

DOI: 10.1038/S41467-019-10173-5

Abstract: The high surface area and porosity, and limitless compound and network combinations between the metal ions and organic ligands making up metal–organic frameworks (MOFs) offer tremendous opportunities for their use in many applications. While numerous methods have been proposed for the synthesis of MOF powders, it is often difficult to obtain oriented crystals with these techniques. Further, the need for additional post-synthesis steps to activate the crystals and release them from the substrate presents a considerable production challenge. Here, we report an acoustically-driven microcentrifugation platform that facilitates fast convective solutal transport, allowing the synthesis of MOF crystals in as short as five minutes. The crystals are not only oriented due to long-range out-of-plane superlattice ordering aided by molecular dipole polarization under the acoustoelectric coupling, but also simultaneously activated during the synthesis process.

Controlled morphogenesis and self-assembly of bismutite nanocrystals into three-dimensional nanostructures and their applications

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C3TA14587E

Abstract: We report the morphogenesis and self-assembly of bismutite nanocrystals with fully tunable morphologies from square plates, octagonal sheets, and round disks into three-dimensional hierarchical nanostructures.

Continuous Production of Janus and Composite Liquid Marbles with Tunable Coverage

Publisher: American Chemical Society (ACS)

Date: 11-07-2016

DOI: 10.1021/ACSAMI.6B05321

Abstract: We report a simple method for on-demand continuous processing of composite liquid marbles with the aid of a 3D printed slide platform, which offers the potential for engineering novel functional surfaces for the production of combination drug therapies, particle-based barcode biomarkers and smart membranes, among other applications. Unlike other attempts at producing such liquid marbles, this novel technique not only facilitates controllable and reproducible production of the liquid marbles but also allows the selection of different morphologies such as banded, patchy, and Janus structures by controlling the coalescence conditions, with the possibility for tunable symmetric and asymmetric patterns, the latter by varying the particle species partitioning ratio.

UV/ozone-assisted low temperature preparation of mesoporous TiO₂with tunable phase composition and enhanced solar light photocatalytic activity

Publisher: Royal Society of Chemistry (RSC)

Date: 16-09-2014

DOI: 10.1039/C4TA04020A

Preface to special topic: Papers from the 13th International conference on surface and colloid science (ICSCS) and the 83rd ACS colloid and surface science symposium, Columbia university, New York, 2009

Publisher: AIP Publishing

Date: 03-2010

DOI: 10.1063/1.3332379

An emerging reactor technology for chemical synthesis: Surface acoustic wave-assisted closed-vessel Suzuki coupling reactions

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.ULTSONCH.2014.02.020

Abstract: In this paper we demonstrate the use of an energy-efficient surface acoustic wave (SAW) device for driving closed-vessel SAW-assisted (CVSAW), ligand-free Suzuki couplings in aqueous media. The reactions were carried out on a mmolar scale with low to ultra-low catalyst loadings. The reactions were driven by heating resulting from the penetration of acoustic energy derived from RF Raleigh waves generated by a piezoelectric chip via a renewable fluid coupling layer. The yields were uniformly high and the reactions could be executed without added ligand and in water. In terms of energy density this new technology was determined to be roughly as efficient as microwaves and superior to ultrasound.

Particle concentration via acoustically driven microcentrifugation: MicroPIV flow visualization and numerical modelling studies

Publisher: Springer Science and Business Media LLC

Date: 05-05-2010

DOI: 10.1007/S10404-009-0452-3

Subwavelength confinement of propagating surface acoustic waves

Publisher: AIP Publishing

Date: 04-01-2021

DOI: 10.1063/5.0038381

Abstract: The ability to confine light to subwavelength scales has led to exciting developments in fields ranging from sensing to single molecule chemistry. In this paper, we demonstrate how arrays of annular hole resonators can be used to confine surface acoustic waves (SAWs) to regions of the propagating surface that are much smaller than the wavelength of the SAWs. These microscopic elastic waves are used in devices for signal processing and sensing and, increasingly, in areas such as quantum information and microfluidics. This work potentially transforms the ability to enhance interactions with SAWs and could pave the way for advances that mirror those in nano-photonics.

Self-assembled highly crystalline TiO2 mesostructures for sunlight-driven, pH-responsive photodegradation of dyes

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.MATERRESBULL.2014.03.036

Piezoelectric ultrasonic resonant motor with stator diameter less than 250 μm: The Proteus motor

Publisher: IOP Publishing

Date: 20-01-2009

DOI: 10.1088/0960-1317/19/2/022001

Microscale capillary wave turbulence excited by high frequency vibration

Publisher: American Chemical Society (ACS)

Date: 07-03-2013

DOI: 10.1021/LA304608A

Abstract: Low frequency (O(10 Hz-10 kHz)) vibration excitation of capillary waves has been extensively studied for nearly two centuries. Such waves appear at the excitation frequency or at rational multiples of the excitation frequency through nonlinear coupling as a result of the finite displacement of the wave, most often at one-half the excitation frequency in so-called Faraday waves and twice this frequency in superharmonic waves. Less understood, however, are the dynamics of capillary waves driven by high-frequency vibration (>O(100 kHz)) and small interface length scales, an arrangement ideal for a broad variety of applications, from nebulizers for pulmonary drug delivery to complex nanoparticle synthesis. In the few studies conducted to date, a marked departure from the predictions of classical Faraday wave theory has been shown, with the appearance of broadband capillary wave generation from 100 Hz to the excitation frequency and beyond, without a clear explanation. We show that weak wave turbulence is the dominant mechanism in the behavior of the system, as evident from wave height frequency spectra that closely follow the Rayleigh-Jeans spectral response η ≈ ω(-17/12) as a consequence of a period-halving, weakly turbulent cascade that appears within a 1 mm water drop whether driven by thickness-mode or surface acoustic Rayleigh wave excitation. However, such a cascade is one-way, from low to high frequencies. The mechanism of exciting the cascade with high-frequency acoustic waves is an acoustic streaming-driven turbulent jet in the fluid bulk, driving the fundamental capillary wave resonance through the well-known coupling between bulk flow and surface waves. Unlike capillary waves, turbulent acoustic streaming can exhibit subharmonic cascades from high to low frequencies here it appears from the excitation frequency all the way to the fundamental modes of the capillary wave at some four orders of magnitude in frequency less than the excitation frequency, enabling the capillary weakly turbulent wave cascade to form from the fundamental capillary wave upward.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

Publisher: American Physical Society (APS)

Date: 20-06-2011

DOI: 10.1103/REVMODPHYS.83.647

Nanoscale plasma-activated aerosol generation for in situ surface pathogen disinfection

Publisher: Springer Science and Business Media LLC

Date: 14-04-2022

DOI: 10.1038/S41378-022-00373-3

Abstract: Plasma treatment constitutes an efficient method for chemical-free disinfection. A spray-based system for dispensing plasma-activated aerosols onto surfaces would facilitate disinfection of complex and/or hidden surfaces inaccessible to direct line-of-sight (for ex le, UV) methods. The complexity and size of current plasma generators (for ex le, plasma jet and cometary plasma systems)—which prohibit portable operation, together with the short plasma lifetimes, necessitate a miniaturized in situ technique in which a source can be simultaneously activated and administered on-demand onto surfaces. Here, we demonstrate this possibility by combining two nanoscale technologies for plasma and aerosol generation into an integrated device that is sufficiently small and lightweight. Plasma is generated on a carpet of zinc oxide nanorods comprising a nanoneedle ensemble, which when raised to a high electric potential, constitutes a massive point charge array with near-singular electric fields to effect atmospheric breakdown. The plasma is then used to activate water transported through an underlying capillary wick, that is subsequently aerosolized under MHz-order surface acoustic waves. We show that the system, besides being amenable to miniaturization and hence integration into a chipscale device, leads to a considerable improvement in plasma-activation over its macroscale cometary discharge predecessor, with up to 20% and 127% higher hydrogen peroxide and nitrite ion concentrations that are respectively generated in the plasma-activated aerosols. This, in turn, leads to a 67% reduction in the disinfection time to achieve 95% bacterial load reduction, therefore demonstrating the potential of the technology as an efficient portable platform for on-demand field-use surface disinfection.

UV Direct Write Metal Enhanced Redox (MER) Domain Engineering for Realization of Surface Acoustic Devices on Lithium Niobate

Publisher: Wiley

Date: 15-04-2014

DOI: 10.1002/ADMI.201400006

On-chip surface acoustic-wave driven microfluidic motors

Publisher: SPIE

Date: 21-12-2011

DOI: 10.1117/12.903220

Phonon‐polariton entrapment in homogenous surface phonon cavities

Publisher: Wiley

Date: 05-02-2016

DOI: 10.1002/ANDP.201500348

Hybrid Surface and Bulk Resonant Acoustics for Concurrent Actuation and Sensing on a Single Microfluidic Device

Publisher: American Chemical Society (ACS)

Date: 06-04-2018

DOI: 10.1021/ACS.ANALCHEM.8B00466

Abstract: While many microfluidic devices have been developed for sensing and others for actuation, few devices can perform both tasks effectively and simultaneously on the same platform. In piezoelectric sensors and actuators, this is due to the opposing operating requirements for sensing and actuation. Sensing ideally requires narrow resonant peaks characterized by high quality factors, such as those found in quartz crystals. However, these materials usually have poor electromechanical coupling coefficients that are not ideal for actuation. In this work, we show that it is possible to achieve both sensing and actuation simultaneously on a shared device by exploiting the distinct advantages of both bulk waves for effective mass sensing and surface waves for highly efficient microfluidic actuation through a unique hybrid surface and bulk acoustic wave platform. In light of the recent resurgence of interest in portable inhaled insulin devices for personalized diabetes management, we demonstrate the use of this technology for efficient aerosolization of insulin for inhalation without denaturing the protein, while being able to concurrently detect the residual mass of the un-nebulized insulin remaining on the device such that the actual dose delivered to the patient can be determined in real time.

Drop manipulation and surgery using electric fields

Publisher: Elsevier BV

Date: 02-2007

DOI: 10.1016/J.JCIS.2006.10.063

Abstract: We study the dynamics of a slender drop sandwiched between two electrodes using lubrication theory. A coupled system of evolution equations for the film thickness and interfacial charge density is derived and simplified for the case of a highly conducting fluid. The contact line singularity is relieved by postulating the existence of a wetting precursor film, which is stabilised by intermolecular forces. We examine the motion of the drop as a function of system parameters: the electrode separation, beta, an electric capillary number, C, and a spatio-temporally varying bottom electrode potential. The possibility of drop manipulation and surgery, which include drop spreading, translation, splitting and recombination, is demonstrated using appropriate tuning of the properties of the bottom potential these results could have potential implications for drop manipulation schemes in various microfluidic applications. For relatively small beta and/or large C values, the drop assumes cone-like structures as it approaches the top electrode the latter stages of this approach are found to be self-similar and a power-law exponent has been extracted for this case.

Mixed mode of dissolving immersed nanodroplets at a solid–water interface

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C4SM02397H

Abstract: The dissolution dynamics of microscopic oil droplets (less than 1 μm in height, i.e. nanodroplets) on a hydrophobilized silicon surface in water was experimentally studied. The lateral diameter was monitored using confocal microscopy, whereas the contact angle was measured by (disruptive) droplet polymerisation of the droplet. In general, we observed the droplets to dissolve in a mixed mode, i.e., neither in the constant contact angle mode nor in the constant contact radius mode. This means that both the lateral diameter and the contact angle of the nanodroplets decrease during the dissolution process. On average, the dissolution rate is faster for droplets with larger initial size. Droplets with the same initial size can, however, possess different dissolution rates. We ascribe the non-universal dissolution rates to chemical and geometric surface heterogeneities (that lead to contact line pinning) and cooperative effects from the mass exchange among neighbouring droplets.

Surface acoustic wave solid-state rotational micromotor

Publisher: AIP Publishing

Date: 16-01-2012

DOI: 10.1063/1.3676660

Abstract: Surface acoustic waves (SAWs) are used to drive a 1 mm diameter rotor at speeds exceeding 9000 rpm and torque of nearly 5 nNm. Unlike recent high-speed SAW rotary motors, however, the present design does not require a fluid coupling layer but interestingly exploits adhesive stiction as an internal preload, a force usually undesirable at these scales with additional preloads, smaller rotors can be propelled to 15 000 rpm. This solid-state motor has no moving parts except for the rotor and is sufficiently simple to allow integration into miniaturized drive systems for potential use in microfluidic diagnostics, optical switching and microrobotics.

Organosilane deposition for microfluidic applications

Publisher: AIP Publishing

Date: 16-08-2011

DOI: 10.1063/1.3625605

Abstract: Treatment of surfaces to change the interaction of fluids with them is a critical step in constructing useful microfluidics devices, especially those used in biological applications. Silanization, the generic term applied to the formation of organosilane monolayers on substrates, is both widely reported in the literature and troublesome in actual application for the uninitiated. These monolayers can be subsequently modified to produce a surface of a specific functionality. Here various organosilane deposition protocols and some application notes are provided as a basis for the novice reader to construct their own silanization procedures, and as a practical resource to a broader range of techniques even for the experienced user.

Simple, low cost MHz-order acoustomicrofluidics using aluminium foil electrodes

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4LC00182F

Abstract: We replicated a wide range of chip-scale acoustofluidics merely with aluminium foil as electrodes on piezoelectric substrates for microfabrication-free low-cost operation.

Rapid dry exfoliation method for tuneable production of molybdenum disulphide quantum dots and large micron-dimension sheets

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C9NR04255E

Abstract: A liquid-free technique is presented for exfoliating molybdenum disulphide into monolayer large sheets or quantum dots using MHz-order sound waves.

High frequency AC electrosprays: Mechanisms and applications

Publisher: WIT Press

Date: 19-04-2006

DOI: 10.2495/AFM06023

High Frequency Sonoprocessing: A New Field of Cavitation‐Free Acoustic Materials Synthesis, Processing, and Manipulation

Publisher: Wiley

Date: 23-11-2020

DOI: 10.1002/ADVS.202001983

Abstract: Ultrasound constitutes a powerful means for materials processing. Similarly, a new field has emerged demonstrating the possibility for harnessing sound energy sources at considerably higher frequencies (10 MHz to 1 GHz) compared to conventional ultrasound (⩽3 MHz) for synthesizing and manipulating a variety of bulk, nanoscale, and biological materials. At these frequencies and the typical acoustic intensities employed, cavitation—which underpins most sonochemical or, more broadly, ultrasound‐mediated processes—is largely absent, suggesting that altogether fundamentally different mechanisms are at play. Ex les include the crystallization of novel morphologies or highly oriented structures exfoliation of 2D quantum dots and nanosheets polymer nanoparticle synthesis and encapsulation and the possibility for manipulating the bandgap of 2D semiconducting materials or the lipid structure that makes up the cell membrane, the latter resulting in the ability to enhance intracellular molecular uptake. These fascinating ex les reveal how the highly nonlinear electromechanical coupling associated with such high‐frequency surface vibration gives rise to a variety of static and dynamic charge generation and transfer effects, in addition to molecular ordering, polarization, and assembly—remarkably, given the vast dimensional separation between the acoustic wavelength and characteristic molecular length scales, or between the MHz‐order excitation frequencies and typical THz‐order molecular vibration frequencies.

Numerical modeling of electro-conjugate fluid flows

Publisher: Elsevier BV

Date: 06-2010

DOI: 10.1016/J.SNA.2010.04.033

Using laser Doppler vibrometry to measure capillary surface waves on fluid-fluid interfaces

Publisher: AIP Publishing

Date: 15-03-2010

DOI: 10.1063/1.3353329

Abstract: Capillary wave phenomena are challenging to study, especially for microfluidics where the wavelengths are short, the frequencies are high, and the frequency distribution is rarely confined to a narrow range, let alone a single frequency. Those that have been studying Faraday capillary waves generated by vertical oscillation have chosen to work at larger scales and at low frequencies as a solution to this problem, trading simplicity in measurement for issues with gravity, boundary conditions, and the fidelity of the subharmonic capillary wave motion. Laser Doppler vibrometry using a Mach–Zehnder interferometer is an attractive alternative: The interface’s motion can be characterized at frequencies up to 40 MHz and displacements of as little as a few tens of picometers.

Rapid fluid flow and mixing induced in microchannels using surface acoustic waves

Publisher: IOP Publishing

Date: 08-2009

DOI: 10.1209/0295-5075/87/47003

Acoustically-Driven Trion and Exciton Modulation in Piezoelectric Two-Dimensional MoS2

Publisher: American Chemical Society (ACS)

Date: 07-01-2016

DOI: 10.1021/ACS.NANOLETT.5B02826

Abstract: By exploiting the very recent discovery of the piezoelectricity in odd-numbered layers of two-dimensional molybdenum disulfide (MoS2), we show the possibility of reversibly tuning the photoluminescence of single and odd-numbered multilayered MoS2 using high frequency sound wave coupling. We observe a strong quenching in the photoluminescence associated with the dissociation and spatial separation of electrons-holes quasi-particles at low applied acoustic powers. At the same applied powers, we note a relative preference for ionization of trions into excitons. This work also constitutes the first visual presentation of the surface displacement in one-layered MoS2 using laser Doppler vibrometry. Such observations are associated with the acoustically generated electric field arising from the piezoelectric nature of MoS2 for odd-numbered layers. At larger applied powers, the thermal effect dominates the behavior of the two-dimensional flakes. Altogether, the work reveals several key fundamentals governing acousto-optic properties of odd-layered MoS2 that can be implemented in future optical and electronic systems.

Actuation mechanisms for microfluidic biomedical devices

Publisher: Elsevier

Date: 2013

DOI: 10.1533/9780857097040.1.100

The extraction of liquid, protein molecules and yeast cells from paper through surface acoustic wave atomization

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B915833B

Abstract: Paper has been proposed as an inexpensive and versatile carrier for microfluidics devices with abilities well beyond simple capillary action for pregnancy tests and the like. Unlike standard microfluidics devices, extracting a fluid from the paper is a challenge and a drawback to its broader use. Here, we extract fluid from narrow paper strips using surface acoustic wave (SAW) irradiation that subsequently atomizes the extracted fluid into a monodisperse aerosol for use in mass spectroscopy, medical diagnostics, and drug delivery applications. Two protein molecules, ovalbumin and bovine serum albumin (BSA), have been preserved in paper and then extracted using atomized mist through SAW excitation protein electrophoresis shows there is less than 1% degradation of either protein molecule in this process. Finally, a solution of live yeast cells was infused into paper, which was subsequently dried for preservation then remoistened to extract the cells via SAW atomization, yielding live cells at the completion of the process. The successful preservation and extraction of fluids, proteins and yeast cells significantly expands the usefulness of paper in microfluidics.

High frequency acoustic permeabilisation of drugs through tissue for localised mucosal delivery

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8LC00355F

Abstract: Localisation of drugs and therapeutic molecules within the mucosa for effective vaccination via a miniature handheld and portable microacoustofluidic device.

Hydrodynamic instability of a thin viscous film between two drops

Publisher: Elsevier BV

Date: 05-2003

DOI: 10.1016/S0021-9797(03)00137-1

Nanoparticle patterning on 128-YX-LN substrates: The effects of surface acceleration and boundary layer streaming

Publisher: IEEE

Date: 11-2008

DOI: 10.1109/ULTSYM.2008.0025

RMIT University

Location: Australia

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Imperial College

Location: United Kingdom of Great Britain and Northern Ireland

View Organisation

Discovery Projects - Grant ID: DP1092955

Start Date: 2010

End Date: 2014

Amount: $290,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP170101061

Start Date: 2017

End Date: 12-2019

Amount: $300,000.00

Funder: Australian Research Council

ARC Future Fellowships - Grant ID: FT130100672

Start Date: 06-2014

End Date: 06-2017

Amount: $989,144.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP140100416

Start Date: 11-2015

End Date: 11-2018

Amount: $326,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP180102110

Start Date: 2018

End Date: 12-2020

Amount: $352,607.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0666660

Start Date: 01-2006

End Date: 12-2009

Amount: $260,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0666549

Start Date: 01-2006

End Date: 12-2008

Amount: $180,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP210101720

Start Date: 03-2021

End Date: 03-2024

Amount: $450,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100108

Start Date: 2010

End Date: 12-2010

Amount: $175,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0985253

Start Date: 2009

End Date: 2014

Amount: $650,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100215

Start Date: 2010

End Date: 12-2010

Amount: $350,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140100805

Start Date: 2014

End Date: 12-2017

Amount: $410,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE110100100

Start Date: 2011

End Date: 12-2013

Amount: $250,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100004

Start Date: 01-2012

End Date: 12-2015

Amount: $470,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE160100228

Start Date: 2016

End Date: 12-2017

Amount: $400,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE200100163

Start Date: 06-2020

End Date: 05-2022

Amount: $700,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668435

Start Date: 2006

End Date: 03-2007

Amount: $1,300,000.00

Funder: Australian Research Council