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STI - School of Engineering
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IMT - Institute of Microengineering
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LMIS4 - Microsyst... |
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Microfluidics for cell manipulation Cells can be manipulated by dielectrophoretic forces created by electrodes embedded in microchannels. Cell manipulations can be combined with sheath flows or with dynamic changes of medium for electroporation or in-flow cell dipping. We also developed a new concept called “liquid electrodes”, which allows to generate lateral forces to focus and separate cells by opposing forces. T. Braschler, N. Demierre et al, ``Continuous separation of cells by balanced dielectrophoretic forces at multiple frequencies,'' Lab on a Chip, 2008. K. Cheung, S. Gawad, and P. Renaud, ``Impedance spectroscopy flow cytometry: On-chip label-free cell differentiation,'' CYTOMETRY, 2007 |
Cells in gels We work on news techniques to trap cells in polymer gels directly in a microchannel. This offers the possibility to generate gel structures with layers of different cells for the study of the biochemical environment on cells, cell-cell interactions and tissue engineering. A. Kunze et al, ``Microfluidic hydrogel layers with multiple gradients to stimulate and perfuse three-dimensional neuronal cell cultures,'' Procedia Chemistry,2009. |
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Cell-based biosensors We are are developing autonomous biosensing platforms, based on living cells, with the aim to use them as nodes of a sensor network system for environmental monitoring. Living cells are used in such a system as the sensor, and secondary probes measure in real time the cellular response to changing environmental conditions. |
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Flexible Neural Probes We have developed flexible microelectrodes for neural implants with specific applications in chronic cortical recording and stimulation. We have successfully recorded from the cortex in animals. Extensive studies for the prevention of the inflammatory reaction of tissues following implantation were performed using immuno-histology techniques. Chemical stimulation of neural tissue is currently studied, by combining electrodes and microfluidic channels on flexible neural probes. A. Mercanzini et al., ``in vivo Electrical Impedance Spectroscopy of Tissue Reaction to Microelectrode Arrays,'' IEEE Transactions on Biomedical Engineering, 2009. |
Sensing Contact Lens We have developed a sensing contact lens. It measures the changes in curvature of the cornea, which are correlated to the change of intra ocular pressure. This device is of major importance for the monitoring of glaucoma patients. The sensor is based on micro-fabricated strain gauge and antenna, connected to a telemetry microprocessor. All components are embedded in a soft contact lens. Leonardi et al., Wireless contact lens sensor for intraocular pressure monitoring: assessment on enucleated pig eyes, J Acta Ophthalmologica 2009 |
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Molecular transport in nanochannels To investigate the transport in nano-confined spaces, chips with two microchannels connected by a nanoslit have been produced. These chips were used for simple diffusion experiments and allowed to demonstrate the exclusion-enrichment effect at low ionic concentrations, which can be used for protein separation and for pre-concentration of ionic species. We showed that it is possible to detect proteins-complex formation using the steady state diffusion phenomenon in T-shaped nanoslit. N. Durand and P. Renaud, ``Label-free determination of protein-surface interaction kinetics by ionic conductance inside a nanochannel,'' Lab on a Chip, 2009. |
FCS in Nanochannels The diffusion of charged proteins in nanochannels with charged surfaces has been investigated with fluorescence correlation spectroscopy (FCS). This technique allows to measure different key parameters, such as the number of molecules diffusing freely inside the nanochannel or interacting with the walls. Different regimes of diffusions were identified. In particular conditions where the diffusion of proteins in nano confined spaces is of the same magnitude as in the bulk were both predicted and verified experimentally. N. Durand et al., ``Direct Observation of Transitions between Surface-Dominated and Bulk Diffusion Regimes in Nanochannels,'' Analytical Chemistry, 2009. |
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Microelectrodes for retinal implants We are developing technlogies for subretinal implants microlelectrode arrays. Tests of biocompatibility have been performed in-vivo. We are also doing numerical simulations to calculate the lateral resolution of stimulation. |
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