Comparative material study between PZT ceramic and newer crystalline PMN-PT and PZN-PT mateirals for composite bimorph actuators.

International audienceThe advent of commercially available giant piezoelectric coefficient monocrystalline materials such as PMN-PT (lead magnesium niobate - lead titanate) or PZN-PT (lead zinc niobate - lead titanate) broadens the gate for silicon-integrated applications (PiezoMEMS). Becoming more compatible with microtechnology batch processes, further advances are expected in terms of miniaturization, optimization, functionality or integration with electronics, all while reducing manufacturing costs. Subsequently, operating voltage will be lower and devices response time will improve dramatically. The paper compiles a base knowledge for composite bimorph actuators in line with a bottom-up approach for further more complex piezoelectric device designs such as "microrobots-on-chips". Material properties and constitutive equations of piezoelectric bimorph cantilevers are initially overviewed. Analytical and finite elements modeling (FEM) are afterwards performed on two designs : classical PZT on copper cantilevers and innovative PMN-PT and PZN-PT on silicon. Comparative results clearly report quantitative improvement of PMN-PT on Si design in terms of tip displacement and blocking force

Packaging using hot-embossing with a polymeric intermediate mould

International audienceHot embossing allows the high precision replication of features from a mould insert into thermoplastic materials. The technique has been developed mainly for microsystem applications, inparticular,the manufacture of micro-optical and micro-fluidic components and systems. It can also be applied to packaging applications. We developed a specific process based on a two-step replication process utilizing hot embossing and a rigid polymeric intermediate mould, which allows the manufacture of complex three-dimensional shapes to realize a functional optical package for optical microsystems

Double hot-embossing with polymeric intermediate mould

Our approach uses a two-step replication process for hot embossing and a rigid polymeric intermediate mould. This process overcomes some geometrical limitations in microstructured mould fabrication, enables positive-tone imprinting, prolongs the lifetime of the master, and lowers the overall cost of the replication proces

Revisiting micro hot-embossing with moulds in non-conventional materials

International audienceManufacturing moulds in non-metallic tooling materials using non conventional structuring techniques is explored for rapid and/or alternative tooling for hot embossing of polymers. Some challenges and advantages of producing embossing tools by deep reactive ion etching (DRIE) in silicon and/or replica-casting in poly(dimethylsiloxane) (PDMS) and utilizing them in the replication process are highlighted

A novel surface wave transducer based on periodically alternated piezoelectric domains

International audienc

Microfluidic chips for the crystallization of biomacromolecules by counter-diffusion and on-chip crystal X-ray analysis.

International audienceMicrofluidic devices were designed to perform on micromoles of biological macromolecules and viruses the search and the optimization of crystallization conditions by counter-diffusion, as well as the on-chip analysis of crystals by X-ray diffraction. Chips composed of microchannels were fabricated in poly-dimethylsiloxane (PDMS), poly-methyl-methacrylate (PMMA) and cyclo-olefin-copolymer (COC) by three distinct methods, namely replica casting, laser ablation and hot embossing. The geometry of the channels was chosen to ensure that crystallization occurs in a convection-free environment. The transparency of the materials is compatible with crystal growth monitoring by optical microscopy. The quality of the protein 3D structures derived from on-chip crystal analysis by X-ray diffraction using a synchrotron radiation was used to identify the most appropriate polymers. Altogether the results demonstrate that for a novel biomolecule, all steps from the initial search of crystallization conditions to X-ray diffraction data collection for 3D structure determination can be performed in a single chip