Publications by Philippe Renaud

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In this work we present an instrumented smart knee prosthesis for in-vivo measurement of forces and kinematics. Studying the constraints, we designed minimal sensory systems to be placed in the polyethylene part of the prosthesis. The magnetic sensors and ...

This paper suggests a new fabrication method for surface micromachining based on porous silicon formation followed by electropolishing. in contrast to its known use as a sacrificial layer, in this work, porous silicon will be employed as constitutive material tur free-standing. mobile microstructures. In one fabrication step, a layer of porous silicon can be generated and released by subsequent electropolishing of a buried layer. This porous silicon layer can be held at the borders as a membrane that is sus

The migration of cells such as leukocytes, tumor cells, and fibroblasts through 3D matrices is critical for regulating homeostasis and immunity and for driving pathogenesis. Interstitial flow through the extracellular matrix, which can substantially increa ...

Living bacteria or yeast cells are frequently used as bioreporters for the detection of specific chemical analytes or conditions of sample toxicity. In particular, bacteria or yeast equipped with synthetic gene circuitry that allows the production of a rel ...

We propose a novel approach to intraocular pressure (IOP) measurement allowing minimal invasive continuous monitoring over prolonged periods, regardless of patient position and activities [1]. The key element of this innovative measurement method is a soft contact lens with a microfabricated strain gage embedded. allowing the measurement of the cornea curvature deformation due to IOP changes. Tests on a eye-simulating device have shown that the sensor is capable of monitoring continuously a deformation of c

We have developed a label-free conductometric platform for the rapid measurement of kinetics parameters for the adsorption and desorption of proteins on surfaces. Adsorbed Bovine Serum Albumin (BSA) has been detected electrically with response times in the ...

In this paper, methods and algorithms are presented for an efficient slicing process specifically designed for microstereolithography, a high-resolution rapid prototyping technology. Modifications are given for different implementation environments (FPU, Parallel Computing, directly wired processes). They use the common STIL-format as the description of the 3D objects and compute bitmapped layers for the layered manufacturing step. Specific attention was paid to the requirements for flexibility, accuracy, s

Single-cell isolation is a truly transformative tool for the understanding of biological systems. It allows single-cell molecular analyses and considers the heterogeneity of cell populations, which is of particular relevance for the diagnosis and treatment ...

We present a microfluidic platform allowing dielectrophoresis-assisted formation of cell aggregates of controlled size and composition under flow conditions. When specific ex- perimental conditions are met, negative dielectrophoresis allows efficient conce ...

Volcano-shaped microelectrodes have demonstrated superior performance in measuring attenuated intracellular action potentials from cardiomyocyte cultures. However, their application to neuronal cultures has not yet yielded reliable intracellular access. Th ...

Planar micromachined spiral inductive structures have applications in many areas such as microelectronics components (filters, low-power components, etc), or such as sensors (proximity sensors) and actuators (electromagnetic micromotors, micropumps, microrelays:, etc). The fabrication of such devices is however rather complicated. In this work we present a new way to realize planar microcoils by using the high-aspect ratio SU8 photoepoxy. Small microinductors with inductances of 0.1 mu H (no magnetic core u

Objective Segmented deep brain stimulation leads in the subthalamic nucleus have shown to increase therapeutic window using directional stimulation. However, it is not fully understood how these segmented leads with reduced electrode size modify the volume ...

The mechanical response of piezoelectric cantilever beams actuated by sol-gel- derived lead zirconium titanate (PZT) thin film is reported. Small multilayered beams are used to analyse the converse piezoelectric effect and to measure the mechanical deflection of the beams with a standard interferometry method. Interferometric displacement measurements, electrical measurements and finite- element simulations are reported to determine the piezoelectric coefficient d(31) of the PZT thin film.

This paper surveys a few of the emerging bioMEMS technologies at EPFL for improved, inexpensive health care. The lab-on-a-chip systems use dielectrophoretic forces to direct cell movement within microfluidic networks and impedance spectroscopy for label-fr ...

Here we show that the transport properties and electrochemical performance of polyelectrolyte membranes are improved through the dispersion of chitosan-wrapped carbon nanotubes, for direct methanol fuel cell applications. Methanol permeability is reduced v ...

Electrical impedance spectroscopy measurements were performed in post-mortem mice brains using a flexible probe with an embedded micrometric electrode array. Combined with a peak resistance frequency method this allowed obtaining intrinsic resistivity valu ...

We present a numerical study of the electrostatic wobble motor. Both finite- element calculations and analytical approaches are used to calculate the torque exerted by the electrodes. Both methods give very similar results, validating an analytical approach. We also study the dynamic behaviour of this type of motor. We show how to optimize the torque by optimally adapting mechanical and electrical parameters.

Microstereolithography is a new microfabrication process that evolved from the rapid prototyping industry. The first developments in this technology started in 1993 and different research teams around the world have developed microstereolithography machines since. All are based on the manufacturing of parts by a light-induced layer-stacking technique, but different approaches have been followed. This paper reviews the major microstereolithography processes developed until now, and presents the components th

Controlling alginate gel formation by diffusion of Ca ions through a filter barrier, a layer-by-layer deposition technique with resolution on the size scale of a single cell is presented. It gives the possibility of exposing cells under biocompatible condi ...

A number of microfabricated flow cytometry devices have been proposed based on electrical(1,2) or optical(3) detection techniques. On chip marker-free differentiation of cells using impedance spectroscopy was demonstrated between leukocyte sub-populations and on erythrocytes+ghosts mixtures.(4) The detection part of the chip includes 4 microelectrodes patterned on the top and bottom walls of a rectangular microchannel which define two detection volumes (Figure 1). Although preliminary results showed the pot

Philippe Renaud

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Instrumented Prosthesis for Knee Implants Monitoring

Free-standing, mobile 3D porous silicon microstructures

Migration dynamics of breast cancer cells in a tunable 3D interstitial flow chamber

An automated microreactor for semi-continuous biosensor measurements

A soft contact lens with a MEMS strain gage embedded for intraocular pressure monitoring

Label-free determination of protein-surface interaction kinetics by ionic conductance inside a nanochannel

Methods and algorithms for the slicing process in microstereolithography

Traceable impedance-based single-cell pipetting, from a research set-up to a robust and fast automated robot: DispenCell-S1

Dielectrophoresis‐assisted creation of cell aggregates under flow conditions using planar electrodes

Impedance spectroscopy of the cell/nanovolcano interface enables optimization for electrophysiology

High aspect ratio planar coils embedded in SU8 photoepoxy for MEMS applications

Analysis of patient-specific stimulation with segmented leads in the subthalamic nucleus

Piezoelectric cantilever beams actuated by PZT sol-gel thin film

BioMEMS for medicine: On-chip cell characterization and implantable microelectrodes

Nafion/chitosan-wrapped CNT nanocomposite membrane for high-performance direct methanol fuel cells

Accurate resistivity mouse brain mapping using microelectrode arrays

Numerical simulations of planar electrostatic wobble motors

Microstereolithography: Concepts and applications

Sequential build-up of hydrogel environments around single cells

Impedance spectroscopy flow cytometry: Model validation