ORCID Profile
0000-0002-9764-7868
Current Organisation
Griffith University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Technology not elsewhere classified | Mechanical Engineering | Microelectromechanical Systems (MEMS)
Scientific Instruments | Expanding Knowledge in Engineering |
Publisher: American Chemical Society (ACS)
Date: 24-10-2016
DOI: 10.1021/ACS.LANGMUIR.6B03266
Abstract: This paper reports the direct and precise measurement of bubble coalescence in salt solutions using microfluidics. We directly visualized the bubble coalescence process in a microchannel using high-speed imaging and evaluated the shortest coalescence time to determine the transition concentration of sodium halide solutions. We found the transition concentration is ion-specific, and the capacity of sodium halide salts to inhibit bubble coalescence follows the order of NaF > NaCl > NaBr > NaI. The microfluidic method overcomes the inherent uncertainties in conventional large-scale devices and methods.
Publisher: Optica Publishing Group
Date: 25-01-2010
DOI: 10.1364/OL.35.000327
Publisher: MDPI AG
Date: 08-05-2017
DOI: 10.3390/MI8050152
Publisher: AIP Publishing
Date: 15-06-2016
DOI: 10.1063/1.4954194
Abstract: We use a microfluidic flow-focusing device with integrated electrodes for controlling the production of water-in-oil drops. In a previous work, we reported that very long jets can be formed upon application of AC fields. We now study in detail the appearance of the long jets as a function of the electrical parameters, i.e., water conductivity, signal frequency, and voltage litude. For intermediate frequencies, we find a threshold voltage above which the jet length rapidly increases. Interestingly, this abrupt transition vanishes for high frequencies of the signal and the jet length grows smoothly with voltage. For frequencies below a threshold value, we previously reported a transition from a well-behaved uniform jet to highly unstable liquid structures in which axisymmetry is lost rather abruptly. These liquid filaments eventually break into droplets of different sizes. In this work, we characterize this transition with a diagram as a function of voltage and liquid conductivity. The electrical response of the long jets was studied via a distributed element circuit model. The model allows us to estimate the electric potential at the tip of the jet revealing that, for any combination of the electrical parameters, the breakup of the jet occurs at a critical value of this potential. We show that this voltage is around 550 V for our device geometry and choice of flow rates.
Publisher: Springer Science and Business Media LLC
Date: 05-03-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B819158A
Abstract: This paper reports the modelling and experimental results of a liquid-core liquid-cladding optofluidic lens. The lens is based on three laminar streams in a circular chamber. The stream lines and the curvature of the interface can be predicted accurately using the theory of two-dimensional dipole flow in a circularly bounded domain. The model establishes basic relations between the flow rate ratio of the core/cladding streams and the radius of curvature and consequently the focal length of the lens. Compared to a rectangular chamber, this new circular design allows the formation of a liquid-core liquid-cladding lens with perfect curvatures. The circular design allows tuning a perfect curvature ranging from the chamber radius itself to infinity. The test device with a circular lens chamber with 1 mm diameter and 50 microm height was fabricated in PDMS. The lens shape as well as the stream lines were characterized using fluorescent dye and tracing particles. Experimental results agree well with the analytical results predicted by the model.
Publisher: American Physical Society (APS)
Date: 21-09-2011
Publisher: MDPI AG
Date: 25-11-2016
DOI: 10.3390/MI7120216
Publisher: IOP Publishing
Date: 21-07-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8LC00106E
Abstract: We present here a novel opto-acousto-fluidic microscopy approach for three-dimensional label-free detection of droplets and cells in microfluidic networks.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6LC00448B
Abstract: We present a novel method for the deformation of droplets in a microfluidic T-junction using an AC electric field.
Publisher: Springer Science and Business Media LLC
Date: 21-03-2018
DOI: 10.1007/S10544-018-0273-9
Abstract: This paper reports a simple method used to fabricate a stretchable conductive polypyrrole (PPy) rough pore-shape polydimethylsiloxane (p-PDMS) device. An abrasive paper is first used to imprint rough micro-structures on the SU-8 micromold. The p-PDMS microchannel is then fabricated using a standard soft-lithography process. An oxygen plasma treatment is then applied to form an irreversible sealing between the microchannel and a blank cover PDMS. The conductive layer is formed by injecting the PPy mixture into the microchannel which polymerizes in the rough pore-shape micro-structures The PPy -PDMS hybrid device shows good electrical property and stretchability. The electrical properties of different geometrical designs of the PPy -PDMS microchannel under stretching were investigated, including straight, curved, and serpentine. Mouse embryonic fibroblasts (NIH/3 T3) were also cultured inside the PPy -PDMS device to demonstrate good biocompatibility and feasibility using the conductive and stretchable microchannel in cell culture microfluidics applications. Finally, cyclic stretching and bending tests were performed to evaluate the reliability of PPy -PDMS microchannel.
Publisher: Springer Science and Business Media LLC
Date: 30-04-2014
DOI: 10.1038/SREP04787
Publisher: Elsevier BV
Date: 02-2021
Publisher: American Chemical Society (ACS)
Date: 02-10-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6LC01435F
Abstract: This review presents the fundamentals of different active methods for sorting droplets in microfluidics.
Publisher: Springer Science and Business Media LLC
Date: 04-2010
Publisher: IOP Publishing
Date: 05-03-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3LC51143J
Abstract: We demonstrate the control of droplet sizes by an ac voltage applied across microelectrodes patterned around a flow-focusing junction. The electrodes do not come in contact with the fluids to avoid electrochemical effects. We found several regimes of droplet production in electric fields, controlled by the connection of the chip, the conductivity of the dispersed phase and the frequency of the applied field. A simple electrical modelling of the chip reveals that the effective voltage at the tip of the liquid to be dispersed controls the production mechanism. At low voltages (≲ 600 V), droplets are produced in dripping regime the droplet size is a function of the ac electric field. The introduction of an effective capillary number that takes into account the Maxwell stress can explain the dependance of droplet size with the applied voltage. At higher voltages (≳ 600 V), jets are observed. The stability of droplet production is a function of the fluid conductivity and applied field frequency reported in a set of flow diagrams.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6LC01007E
Abstract: We proposed and developed a novel viscoelastic ferrofluid, and demonstrated its superior advantages for continuous sheathless separation of nonmagnetic particles.
Publisher: American Physical Society (APS)
Date: 07-09-2018
Publisher: Elsevier BV
Date: 06-2018
Publisher: Springer Science and Business Media LLC
Date: 04-2016
Publisher: IOP Publishing
Date: 02-03-2009
Publisher: Springer Science and Business Media LLC
Date: 08-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6RA25328H
Abstract: Sheathless particle focusing and separation in viscoelastic fluid is demonstrated using an integrated ECCA (straight channel section with asymmetrical expansion–contraction cavity arrays) straight channel.
Publisher: MDPI AG
Date: 17-08-2017
DOI: 10.3390/MI8080254
Publisher: American Chemical Society (ACS)
Date: 17-08-2017
DOI: 10.1021/ACS.ANALCHEM.7B02671
Abstract: This work investigates the on-chip washing process of microparticles and cells using coflow configuration of viscoelastic fluid and Newtonian fluid in a straight microchannel. By adding a small amount of biocompatible polymers into the particle medium or cell culture medium, the induced viscoelasticity can push particles and cells laterally from their original medium to the coflow Newtonian medium. This behavior can be used for particle or cell washing. First, we demonstrated on-chip particle washing by the size-dependent migration speed using coflow of viscoelastic fluid and Newtonian fluid. The critical particle size for efficient particle washing was determined. Second, we demonstrated continuous on-chip washing of Jurkat cells using coflow of viscoelastic fluid and Newtonian fluid. The lateral migration process of Jurkat cells along the channel length was investigated. In addition, the cell washing quality was verified by hemocytometry and flow cytometry with a recovery rate as high as 92.8%. Scanning spectrophotometric measurements of the media from the two inlets and the two outlets demonstrated that diffusion of the coflow was negligible, indicating efficient cell washing from culture medium to phosphate-buffered saline medium. This technique may be a safer, simpler, cheaper, and more efficient alternative to the tedious conventional centrifugation methods and may open up a wide range of biomedical applications.
Publisher: Springer Science and Business Media LLC
Date: 04-12-2015
DOI: 10.1038/SREP17811
Abstract: Using a combination of low-pressure oxygen and high temperatures, isotropic and anisotropic silicon (Si) etch rates can be controlled up to ten micron per minute. By varying the process conditions, we show that the vertical-to-lateral etch rate ratio can be controlled from 1:1 isotropic etch to 1.8:1 anisotropic. This simple Si etching technique combines the main respective advantages of both wet and dry Si etching techniques such as fast Si etch rate, stiction-free and high etch rate uniformity across a wafer. In addition, this alternative O 2 -based Si etching technique has additional advantages not commonly associated with dry etchants such as avoiding the use of halogens and has no toxic by-products, which improves safety and simplifies waste disposal. Furthermore, this process also exhibits very high selectivity ( :1) with conventional hard masks such as silicon carbide, silicon dioxide and silicon nitride, enabling deep Si etching. In these initial studies, etch rates as high as 9.2 μm/min could be achieved at 1150 °C. Empirical estimation for the calculation of the etch rate as a function of the feature size and oxygen flow rate are presented and used as proof of concepts.
Publisher: AIP Publishing
Date: 20-08-2007
DOI: 10.1063/1.2773948
Abstract: Precise dispensing of microdroplets is an important process for droplet-based microfluidics. The droplet formation by shear force between two immiscible fluids depends on their flow rates, the viscosities, and the interfacial tension. In this letter, the authors report the use of integrated microheater and temperature sensor for controlling the droplet formation process. The technique exploits the dependency on temperature of viscosities and interfacial tension. Using a relatively low heating temperature ranging from 25to70°C, the droplet diameter can be adjusted to over two times of its original value. The relatively low temperature range makes sure that this concept is applicable for droplets containing biological s les.
Publisher: American Chemical Society (ACS)
Date: 07-07-2010
DOI: 10.1021/LA101474E
Abstract: Motion of a droplet on a planar surface has applications in droplet-based lab on a chip technology. This paper reports the experimental results of the shape, contact angles, and motion of ferrofluid droplets driven by a permanent magnet on a planar homogeneous surface. The water-based ferrofluid in use is a colloidal suspension of single-domain magnetic nanoparticles. The effect of the magnetic field on the apparent contact angle of the ferrofluid droplet was first investigated. The results show that an increasing magnetic flux decreases the apparent contact angle of a sessile ferrofluid droplet. Next, the dynamic contact angle was investigated by observing the shape and the motion of a sessile ferrofluid droplet. The advancing and receding contact angles of the moving ferrofluid were measured at different moving speeds and magnetic field strengths. The measured contact angles were used to estimate the magnitude of the forces involved in the sliding motion. Scaling analysis was carried out to derive the critical velocity, beyond which the droplet is not able to catch up with the moving magnet.
Publisher: Elsevier BV
Date: 08-2018
Publisher: American Chemical Society (ACS)
Date: 16-02-2017
DOI: 10.1021/ACS.ANALCHEM.6B05053
Abstract: We introduce an effective method to actively induce droplet generation using negative pressure. Droplets can be generated on demand using a series of periodic negative pressure pulses. Fluidic network models were developed using the analogy to electric networks to relate the pressure conditions for different flow regimes. Experimental results show that the droplet volume is correlated to the pressure ratio with a power law of 1.3. Using a pulsed negative pressure at the outlet, we are able to produce droplets in demand and with a volume proportional to the pulse width.
Publisher: IOP Publishing
Date: 12-03-2008
Publisher: Springer Science and Business Media LLC
Date: 12-12-2018
Publisher: Springer Science and Business Media LLC
Date: 02-07-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4LC01139B
Abstract: We report a new technology using acoustofluidic to achieve controllable manipulation of the size of the bubbles formed.
Publisher: American Chemical Society (ACS)
Date: 25-11-2020
DOI: 10.1021/ACS.ANALCHEM.9B04219
Abstract: We introduce a unique system to achieve on-demand droplet merging and splitting using a perpendicular AC electric field. The working mechanism involves a micropillar to split droplets, followed by electrocoalescence using an AC electric field. Adjusting the parameters of the AC signal and conductivity of the fluid result in different merging regimes. We observed a minimum threshold voltage and a strong influence of the surfactant. We hypothesize that the merging process is caused by dipole-dipole coalescence between the daughter droplets. At the same time, adjustment of the conductivity reveals a shift in the merging regimes and can be explained with an electric circuit diagram. Size-based sorting using this merging phenomenon is subsequently demonstrated, where alternate, single, double, and triple droplets sorting were achieved. The concept presented in this paper is potentially useful for drug dispensing or multivolume digital polymerase chain reaction, as droplets of multiple sizes can be generated simultaneously.
Publisher: Springer Science and Business Media LLC
Date: 20-03-2017
Publisher: IOP Publishing
Date: 13-07-2009
Publisher: American Chemical Society (ACS)
Date: 12-02-2019
DOI: 10.1021/ACS.LANGMUIR.8B03486
Abstract: Interfacial gas enrichment (IGE) of dissolved gases in water is shown to govern the strong attraction between solid hydrophobic surfaces of an atomic force microscopy (AFM) colloidal probe and solid substrate. However, the role of IGE in controlling the attraction between fluid-fluid interfaces of foam films and emulsion films is difficult to establish by AFM techniques because of the extremely fast coalescence. Here, we applied droplet-based microfluidics to capture the fast coalescence event under the creeping flow condition and quantify the effect of IGE on the drainage and stability of water films between coalescing oil droplets. The amount of dissolved gases is controlled by partially degassing the oil phase. When the amount of dissolved gases (oxygen) in oil decreases (from 7.89 to 4.59 mg/L), the average drainage time of coalescence significantly increases (from 19 to 50 ms). Our theoretical quantification of the coalescence by incorporating IGE into the multilayer van der Waals attraction theory confirms the acceleration of film drainage dynamics by the van der Waals attractive force generated by IGE. The thickness of the IGE layer decreases from 5.5 to 4.9 nm when the amount of dissolved gas decreases from 7.89 to 4.59 mg/L. All these results establish the universal role of dissolved gases in governing the strong attraction between particulate hydrophobic interfaces.
Publisher: MDPI AG
Date: 22-11-2016
DOI: 10.20944/PREPRINTS201611.0086.V2
Abstract: Surface acoustic wave (SAW) is effective for the manipulation of fluids and particles in microscale. The current approach of integrating interdigitated transducers (IDTs) for SAW generation into microfluidic channels involves complex and laborious microfabrication steps. These steps often require the full access to clean room facilities and hours to align the transducers to the precise location. This work presents an affordable and innovative method for fabricating SAW-based microfluidic devices without the need of clean room facilities and alignment. The IDTs and microfluidic channels are fabricated in the same process and thus precisely self-aligned in accordance with the device design. With the use of the developed fabrication approach, a few types of different SAW-based microfluidic devices have been fabricated and demonstrated for particle separation and active droplet generation.
Publisher: MDPI AG
Date: 17-11-2016
DOI: 10.20944/PREPRINTS201611.0086.V1
Abstract: Surface acoustic wave (SAW) is effective for the manipulation of fluids and particles in microscale. The current approach of integrating interdigitated transducers (IDTs) for SAW generation into microfluidic channels involves complex and laborious microfabrication steps. These steps often require the full access to clean room facilities and hours to align the transducers to the precise location. This work presents an affordable and innovative method for fabricating SAW-based microfluidic devices without the need of clean room facilities and alignment. The IDTs and microfluidic channels are fabricated in the same process and thus precisely self-aligned in accordance with the device design. With the use of the developed fabrication approach, a few types of different SAW-based microfluidic devices have been fabricated and demonstrated for particle separation and active droplet generation.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5LC01012H
Abstract: This review presents the state of the art of active microfluidic droplet generation concepts.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6AN00659K
Abstract: Environmental (air, inert gas, vacuum) stability and vacuum oven desiccation for high sensitivity nanoscale silicon SALDI-MS is investigated.
Publisher: AIP Publishing
Date: 09-2010
DOI: 10.1063/1.3466882
Abstract: Rapid prototyping of polydimethylsiloxane (PDMS) is often used to build microfluidic devices. However, the inherent hydrophobic nature of the material limits the use of PDMS in many applications. While different methods have been developed to transform the hydrophobic PDMS surface to a hydrophilic surface, the actual implementation proved to be time consuming due to differences in equipment and the need for characterization. This paper reports a simple and easy protocol combining a second extended oxygen plasma treatments and proper storage to produce usable hydrophilic PDMS devices. The results show that at a plasma power of 70 W, an extended treatment of over 5 min would allow the PDMS surface to remain hydrophilic for more than 6 h. Storing the treated PDMS devices in de-ionized water would allow them to maintain their hydrophilicity for weeks. Atomic force microscopy analysis shows that a longer oxygen plasma time produces a smoother surface.
Publisher: American Chemical Society (ACS)
Date: 05-05-2020
Location: Germany
Start Date: 2017
End Date: 12-2019
Amount: $360,000.00
Funder: Australian Research Council
View Funded Activity