Philippe Renaud

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Biography and current work

Mission

The research of our group focuses on the study of new micro-fabricated devices based on silicon and polymer microtechnology and of their integration for the realization of new types of hybrid or monolithic microsystems. We are currently focusing on three main axis of research:

BioMEMS and Microfluidics:
Several projects are focused on biosciences applications. We are studying new concepts to perform flow cytometry in microfluidic systems. Cells are analysed by impedance spectroscopy while flowing through microchannels. The objective is to achieve in-situ cell separation after electrical identification. Cell electroporation micro-devices are also studied. We also develop silicon micro-fluidic components (pumps, flow regulators, valves) for drug delivery.The physical phenomena in microflows and the use of bubbles in microchannels are studied. An implantable pressure sensor with telemetry reading has also been realized. We fabricated a multielectrode array for long-term stimulation and measurement of electrical activity of different biological tissues. Results were obtained with chicken dissociated neuron cultures, rat spinal cord slice cultures and neonatal rat cardiomyocyte cultures. Flexible microelectrodes that are combined with microfluidic channels are developed for use as active neural probes.

Polymer Microstructures:
We developed a new process of integral microstereolithography that allows building arbitrary 3D microparts with a resolution of 3 micrometers in lateral and vertical directions. A new project on nanoparticle loaded polymers for SPL. We have developed, in collaboration with IBM, a new class of ultra-thick photoresist to be used in UV-LIGA for making high-resolution injection moulds and metal microparts. We are also developing polyimide processes.

Advanced Silicon Microsystems:
Special silicon processing technologies have been developed in the EPFL Center for Microtechnology (CMI). Electrothermal1D and 2D scanning micro-mirror have been realized for barcode reading applications and image projection. An innovative technology that employs multilayer interference filters made out of porous silicon has been used in an integrated gas analyser. This consists of a scanning porous silicon filter plate that is moved by a thermal micro-actuator. An infrared source based on silicon technology has been used in a miniature photoacoustic sensor. The technologies for a silicon microreactor for high temperature gas phase synthesis have been studied. The stability of heating elements at high temperature (above 700°C) is a critical issue in such devices. A project on optical switching has started. A new class of gas sensors that is using micro-plasma discharge effect is currently studied for integration on silicon chips.

Philippe Renaud