Publications by Arnaud Bertsch

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Mixing liquids on the micro-scale is difficult because the low Reynolds numbers in microchannels and in microreactors prohibit the use of conventional mixing techniques based on mechanical stirring which induces turbulence. Static mixers can be used to solve this mixing problem. In this paper, micromixers having geometries very close to those of conventional large-scale static mixers used in the chemical and food-processing industry are presented. Two kind of geometries have been studied. The first type of

We present a finite element based simulation and analysis method to describe the spatial extent of stimulation and the effects of electrode–tissue interactions in subretinal prostheses. In particular, we estimate the threshold stimulation current needed to ...

We present a microfluidic dielectrophoretic-actuated system designed to trap chosen single-cell and form controlled cell aggregates. A novel method is proposed to characterize the efficiency of the dielectrophoretic trapping, considering the flow speed but ...

We present the fabrication, characterization, use in cortical recording and histological results of a flexible implantable neural probe. The microfabricated device is implemented in polyimide and platinum providing mechanical flexibility, high quality elec ...

The present paper describes a microfluidic oscillator based on facing impinging jets and operating in laminar flow conditions. Using appropriate microchannel configurations, pulsatile liquid flows are generated at the microscale from steady and equal inlet ...

For over 30 years, carbon fiber microelectrodes have been the gold standard for measurements related to exocytosis and more generally to the processes taking place at the synaptic level. However, this method has a low throughput and molecules can escape de ...

The increasing interests in micro-electro-mechanical systems (MEMS) has raised the requirement for photoresist materials with improved friction and wear properties for mechanically loaded 3D shaped microstructures. In this work, SU8 photoresist layers rein ...

This paper describes new polymer/ceramic photosensitive resins that can be used in the microstereolithography process for manufacturing complex 3D components in composite material. These new resins contain high loads (up to 80 wt.%) of alumina nanoparticles, used as fillers in a photosensitive acrylate-based resin of low viscosity. With the nanopowder-filled resin we developed, various small polymer/alumina composite components having a real geometric complexity were produced with small manufacturing times.

A conductive composite photoresist has been developed for the direct photopatterning of electrodes. It is based on a dispersion of silver nanoparticles in SU8, a non-conductive, negative-tone photoresist. Manufactured structures have an electrical conducti ...

Microstereolithography is a technology at the interface of the microengineering and rapid prototyping domains. It has evolved from the stereolithography technique, and is also based on a light-induced layer- stacking manufacturing, As the resolution of the microstereolithography technique is far better than the one of rapid prototyping technologies, this technique is of particular interest in the microengineering domain where its 3D capability allows the production of components no other microfabrication te

This paper describes F-based dry etching and resulting surface properties of biocompatible silicone elastomer. The etch rate of polysiloxane and surface morphology was found to be highly temperature dependent. An increase in temperature results in a signif ...

The use of low-stress SU8 nanocomposites as a functional material for micro- parts and coating applications is described in this paper. It was found that the nanoparticles lower the internal stress and decrease the wear rate and frictional coefficient of t ...

In this paper, a new microstereolithography apparatus is described. It is an integral process in which a complete layer can be made in one exposure only, in contrast to vector-by-vector processes which are based on the vectorial tracing of each layer. As for most microstereolithography processes, complex objects can be realized by superimposing layers, each layer being obtained by a light-induced polymerization of a liquid resin. The vertical and transverse resolution of the process we are developping have

Smell loss is a sensory impairment that has major consequences in many areas of daily life and for which current therapies are insufficient. A prosthesis-type technology enabling patients to sample their olfactory environment has not yet been developed. The aim of our study was, therefore, to test whether stimulation of the intranasal trigeminal system by a device combining an artificial nose with an intranasal electrical stimulator will enable patients to detect and discriminate odorant molecules. Four exp

This paper describes the development of a polyimide/SU-8 catheter-tip MEMS gauge pressure sensor. Finite element analysis was used to investigate critical parameters, impacting on the device design and sensing characteristics. The sensing element of the device was fabricated by polyimide-based micromachining on a flexible membrane, using embedded thin-film metallic wires as piezoresistive elements. A chamber containing this flexible membrane was sealed using an adapted SU-8 bonding technique. The device was

Micro and nanoparticles made from polymers, metals, ceramics, and lipids are crucial for biomedical devices, energy storage, and electronics. Traditional fabrication methods like grinding, milling, and emulsification result in monolithic shapes and heterog ...

This work demonstrates the controllable fabrication of polyvinylidene fluoride (PVDF) piezoelectric microsprings by melt electrowriting (MEW) with tunable geometrical parameters. By precisely coordinating transverse and rotational motions, the crossing angle and spiral topology of the micro-spring can be programmed with high fidelity. Systematic experiments further reveal that geometry and processing speed strongly affect the electroactive phase fraction of PVDF fibers, which ranged from

In this work, we report a nanofluidic gating mechanism that uses the thermal effect for modulating the ionic transport inside nanofluidic channels. The control of the ionic transport inside a nanochannel is demonstrated using electrical conductivity. A the ...

A new approach for the realization of true 3D polymer structures is presented in this paper. It consists in adding, in a post-processing microstereolithography step, 3D polymer microstructures on top of a micropart patterned by means of planar processes such as thin films, bulk silicon etching or high aspect ratio structuration (LIGA, RIE, thick resist). In this way, some shape limitations of the planar technologies can be overcome for new functional applications. Moreover, the direct processing of microste

We present a novel study on label-free recognition and distinction of drug resistant breast cancer cells (MCF-7 DOX) from their parental cells (MCF-7 WT) via impedimetric measurements. Drug resistant cells exhibited significant differences in their dielect ...

Arnaud Bertsch

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3D micromixers - Downscaling large scale industrial static mixers

Simulations to study spatial extent of stimulation and effect of electrode–tissue gap in subretinal implants

Dielectrophoretic Traps for Efficient Bead and Cell Trapping and Formation of Aggregates of Controlled Size and Composition

Demonstration of cortical recording using novel flexible polymer neural probes

Feedback-free microfluidic oscillator with impinging jets

Rapid exocytosis kinetics measured by amperometry within volcano microelectrodes

SU-8 nanocomposite coatings with improved tribological performance for MEMS

Ceramic microcomponents by microstereolithography

Conductive SU8 Photoresist for Microfabrication

Microstereolithography: a review

Fluorine based plasma treatment of biocompatible silicone elastomer. Effect of temperature on etch rate and surface properties

Effect of filler behavior on nanocomposite SU8 photoresist for moving micro- parts

Microstereolithography: a new process to build complex 3D objects

Substitution of human olfaction by the trigeminal system

Polyimide/SU-8 catheter-tip MEMS gauge pressure sensor

Additive manufacturing of water-soluble 3D micro molds for complex-shaped lipid microparticles

Piezoelectricity Enhancement Investigation of PVDF Micro-Springs Fabricated by Melt Electrowriting

Thermal control of ionic transport and fluid flow in nanofluidic channels

3D microfabrication by combining microstereolithography and thick resist UV lithography

Label-Free Recognition of Drug Resistance via Impedimetric Screening of Breast Cancer Cells