ORCID Profile
0000-0002-6333-285X
Current Organisations
University of Melbourne
,
Université de Sherbrooke
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Publisher: Elsevier BV
Date: 11-2020
Publisher: IEEE
Date: 07-2019
Publisher: arXiv
Date: 2020
Publisher: American Chemical Society (ACS)
Date: 10-02-2020
Abstract: Innovations in micro- and nanofabrication technologies enable the manufacture of multielectrode arrays for use in neuromodulation and neural recording. Multielectrode arrays make possible medical implants such as pacemakers, deep-brain stimulators, or visual and hearing aids, to treat numerous neural disorders. An optimal neural interface requires a high density of electrodes to precisely record from and stimulate the nervous system while minimizing the overall size of the array. For ex le, people with retinal degenerative diseases can benefit from retinal prostheses implanted inside the eye. However, at present the visual acuity provided by such implants is well below the threshold for functional vision, mainly due to the limited spatial resolution. In this work, we present a design of 3D nanostructured conductive diamond electrodes, integrated within a polycrystalline diamond housing, offering a high electrode density and count, which simultaneously satisfies spatial resolution and biocompatibility goals. The array is composed of height adjustable pillar electrodes that are 80 μm in diameter and separated by 150 μm. A holistic characterization of the electrodes was performed and the device tested for stimulation performance in a whole-mounted retina. Electrochemical testing showed impedance of 20 kΩ and a wide water window of 2.47 V. The pillar structure allows the distance between the electrodes and the retinal ganglion cells to be reduced which is key to more confined stimulation at lower current levels, leading to potentially higher-acuity stimulation without damaging retinal tissue.
Publisher: IEEE
Date: 10-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6BM00125D
Abstract: A novel, ultrasound based approach for the dynamic stimulation and promotion of tissue healing processes employing surface acoustic waves on a chip is presented for the ex le of osteoblast-like Saos-2 cells.
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.BIOMATERIALS.2019.119648
Abstract: Implantable medical devices are now in regular use to treat or ameliorate medical conditions, including movement disorders, chronic pain, cardiac arrhythmias, and hearing or vision loss. Aside from offering alternatives to pharmaceuticals, one major advantage of device therapy is the potential to monitor treatment efficacy, disease progression, and perhaps begin to uncover elusive mechanisms of diseases pathology. In an ideal system, neural stimulation, neural recording, and electrochemical sensing would be conducted by the same electrode in the same anatomical region. Carbon fiber (CF) microelectrodes are the appropriate size to achieve this goal and have shown excellent performance, in vivo. Their electrochemical properties, however, are not suitable for neural stimulation and electrochemical sensing. Here, we present a method to deposit high surface area conducting diamond on CF microelectrodes. This unique hybrid microelectrode is capable of recording single-neuron action potentials, delivering effective electrical stimulation pulses, and exhibits excellent electrochemical dopamine detection. Such electrodes are needed for the next generation of miniaturized, closed-loop implants that can self-tune therapies by monitoring both electrophysiological and biochemical biomarkers.
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.JCMS.2017.05.025
Abstract: This study aimed to assess the impact of different abutment materials on peri-implant tissue regeneration after surgical treatment of peri-implantitis in a large animal model. Titanium implants (n = 51) were inserted in the upper and lower jaw of eight beagle dogs and a peri-implant infection was induced. After two months the peri-implant infection was surgically treated and abutments with different surfaces (Ti-2: n = 14 CoCrMb: n = 13 Ag-modified Ti-4: n = 14 Ti-4 control: n = 10) were applied. Clinical attachment level (CAL), modified sulcus bleeding index (mBI), bleeding on probing (BoP), and the sulcus fluid flow rate (SFFR) were determined 4, 8, and 12 weeks after surgical treatment to document the peri-implant tissue reaction. Superior levels for CAL and mBI were found with the Ti-4 control and the Ag-modified abutments, with the Ag-modified abutments showing the best values after 12 weeks. Lowest SFFR values compared with the other treatment groups underlined the superior soft tissue reaction adjacent to Ag-modified abutments. After 12 weeks inferior CAL, SFFR, BOP and mBI values were documented for the Ti-2 surface. Within limitations of the study, Ag-modified abutments lead to superior tissue reactions. Further studies are needed to investigate the properties of abutment materials.
Publisher: Elsevier BV
Date: 12-2017
Publisher: American Physical Society (APS)
Date: 15-10-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8RA07416J
Abstract: By combination of particle image velocimetry and live cell imaging in an acoustically driven microfluidic chamber, we study shear and cell density dependent adhesion. We find excellent agreement with simulations considering pure geometrical effects.
Publisher: Frontiers Media SA
Date: 27-01-2021
DOI: 10.3389/FNINS.2021.629056
Abstract: The study of neurons is fundamental for basic neuroscience research and treatment of neurological disorders. In recent years ultrasound has been increasingly recognized as a viable method to stimulate neurons. However, traditional ultrasound transducers are limited in the scope of their application by self-heating effects, limited frequency range and cavitation effects during neuromodulation. In contrast, surface acoustic wave (SAW) devices, which are producing wavemodes with increasing application in biomedical devices, generate less self-heating, are smaller and create less cavitation. SAW devices thus have the potential to address some of the drawbacks of traditional ultrasound transducers and could be implemented as miniaturized wearable or implantable devices. In this mini review, we discuss the potential mechanisms of SAW-based neuromodulation, including mechanical displacement, electromagnetic fields, thermal effects, and acoustic streaming. We also review the application of SAW actuation for neuronal stimulation, including growth and neuromodulation. Finally, we propose future directions for SAW-based neuromodulation.
Publisher: AIP Publishing
Date: 03-2023
DOI: 10.1063/5.0134605
Abstract: Excitation using surface acoustic waves (SAW) has demonstrated efficacy in improving microscale particle/chemical transport due to its ability to generate microscale wavelengths. However, the effects of acoustic stimulation on transport processes along the length of sub-wavelength microchannels and their underlying mechanisms, essential for long-range transport, have not been examined in detail. In this work, we investigate diffusion along the length of subwavelength microchannels using experimental and simulation approaches, demonstrating enhanced transport under SAW excitation. The microchannel-based enhanced diffusion mechanisms are further studied by investigating the acoustic pressure and streaming fields, finding that the degree of enhancement is a function of applied power, microchannel dimensions, and viscosity. This microchannel-based diffusion enhancement approach is applicable to microfluidic and biomedical microscale transport enhancement, with the findings here being relevant to acoustic-based micro-mixing and neurodegenerative therapies.
Publisher: AIP Publishing
Date: 16-11-2015
DOI: 10.1063/1.4935563
Abstract: We demonstrate continuous, passive, and label-free sorting of different in vitro cancer cell lines (MV3, MCF7, and HEPG2) as model systems for circulating tumor cells (CTCs) from undiluted whole blood employing the non-inertial lift effect as driving force. This purely viscous, repulsive cell-wall interaction is sensitive to cell size and deformability differences and yields highly efficient cell separation and high enrichment factors. We show that the performance of the device is robust over a large range of blood cell concentrations and flow rates as well as for the different cell lines. The collected s les usually contain more than 90% of the initially injected CTCs and exhibit average enrichment factors of more than 20 for sorting from whole blood s les.
Publisher: MDPI AG
Date: 21-10-2016
Publisher: Elsevier BV
Date: 10-2020
Publisher: IOP Publishing
Date: 23-12-2019
Abstract: Retinal prosthetic devices hold great promise for the treatment of retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. Through electrical stimulation of the surviving retinal neurons, these devices evoke visual signals that are then relayed to the brain. Currently, the visual prostheses used in clinical trials have few electrodes, thus limiting visual acuity. Electrode arrays with high electrode densities have been developed using novel technologies, including diamond growth and laser machining, and these may provide a more promising route to achieve high visual acuity in blind patients. Here, we studied the potential spatial resolution of electrical stimulation using diamond electrodes. We did this by labeling retinal ganglion cells in whole mount retina with a calcium indicator in wild-type rats and those with retinal degeneration. We imaged the ganglion cell responses to a range of stimulation parameters, including pulse duration and return electrode configuration. With sub-retinal stimulation, in which electrodes were in contact with the intact or degenerated photoreceptor layer, we found that biphasic pulses of 0.1 ms phase duration and a local return configuration was the most effective in confining the retinal ganglion cell activation patterns, while also remaining within the safety limits of the materials and providing the best power efficiency. These results provide an optimized stimulation strategy for retinal implants, which if implemented in a retinal prosthetic is expected to improve the achievable visual acuity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3LC50916H
Abstract: For an optimal implementation of materials, such as, e.g. medical implants in living environments, a thorough characterization of cell adhesion, kinetics and strength is required, as well as a prerequisite e.g. for bone integration. Here we present a miniaturized (~100 μl) lab-on-a-chip implant hybrid system which allows quantification of cell adhesion under dynamic conditions mimicking those of physiological relevance. Surface acoustic waves are excited and used on optical transparent chips to induce micro acoustic streaming and to create a microfluidic shear spectrum ranging from 0 to ~35 s(-1). We demonstrate its potential for a time-efficient, dynamic screening test of new implant materials using a model of an osseointegration with SAOS-2 cells. The upside-down orientation also allows utilization of the micro reactor on non-transparent materials like titanium and diamond-like-carbon (DLC).
No related grants have been discovered for Melanie Stamp.