FAtigue of titanium polycrystals for BIO-MEDical micro-systems – FABIOMED

The proposed project is focus on the fatigue design of titanium micro-membrane whose thickness is inferior to a few microns and used in biomedical application (micro-valves and
pressure sensors). The reliability of these components in the context of high cycle fatigue, has been given only very limited attention though this aspect largely affects their robustness. For these devices, the thickness being of the same order of magnitude as the size of the crystals, the effect of microstructural heterogeneities on the fatigue strength can no longer be ignored. Considering the role of microstructural heterogeneities on fatigue failure is a difficult task that need development of a specific fatigue design approach adapted to microsystems. The project is located at the interface between mechanics of materials, micromechanics and microfabrication technologies. The consortium formed to meet the aforementioned objectives includes two academic laboratories (LAMPA and C2N) and a company (MISTIC). The LAMPA (LAboratory of Mechanics, Processes and innovAtion) has expertise in the field of
mechanical testing (particularly fatigue testing) and microstructural characterization (X-ray diffraction, EBSD) of metallic materials. The aim of the LAMPA thesis will to develop a fatigue design approach adapted to microsystem. The C2N (Center for Nanosciences and Nanotechnologies) has a strong expertise on the design, manufacturing and testing of microsystems. The C2N has developed original testing methods for small-scale components. The aim of the C2N thesis will to characterize microsystems in fatigue and to propose design rules that improve the fatigue resistance. MISTIC designs, prototypes and industrializes microsystems for manufacturers of active implantable medical devices. The proposed project will allow MISTIC to overcome the difficulties associated with the fatigue design of implantable pressure sensors, which a key step for the development of this product.