Microfluidique Supercritique – µFS

The aim of this Supercritical Microfluidics project (µFSC) is to develop scientific and technical knowledge, allowing to design, realize, and use microfluidic devices, that concern for the first time supercritical fluids in wide ranges of temperature and pressure. Maximum operating conditions are up to 50 MPa for pressure and 500°C for temperature, in order to cover both fundamental and applied challenges associated to hydrothermal supercritical fluids. Nevertheless, in more moderate ranges of pressure (' 40 MPa) and temperature (' 400 °C), this project already deals with many original topics to develop our basic scientific knowledge, especially in the fields of condensed matter, material sciences, engineering processes, and also in Earth sciences. In order to manage this challenge, the three partners located in Bordeaux, Marseille, and Toulouse, have associated complementary skills for instrumentation and measurements, and in modelling and numerical simulation to understand the supercritical microfluidic devices behaviour, and to establish the fundamental links between 'gas' microfluidics and 'liquid' microfluidics. Indeed, by enlarging the pressure and temperature operating conditions of the classical microfluidic devices, it becomes possible to cross the critical point and then to investigate the monophasic and multiphasic states of most of real fluids. Therefore 'supercritical' microfluidics can be a winning scheme that benefits from the thermocompressible link (now well-known by the partners) between compressible aerodynamics and uncompressible hydrodynamics. Optimization will be used to avoid some well identified drawbacks of classical devices behaviour (as for example the mixing of chemical species), and to benefit at best from the many advantages ' widely evidenced in the last decade by a rich literature on MEMS (Micro Electronics Mechanical Systems) ' of the size reduction for the supercritical fluidic reactor. This project is a pioneering approach in the world, supported by research programs at a regional level (research grants, competitivity poles, GIS) and at a French national level (CNES research program in Matter Sciences). Our approach is based on recent developments in modelling on hyperdilatable and hypercompressible fluids confined flows. It takes benefit from several key technological steps in miniaturization of instrumentation under pressure realized (1) during the development (2001-2007) of the instrumentation for space experiments on critical and supercritical fluids (using the CNES DECLIC instrument), (2) during a PhD work (2003-2006) on flow studies of supercritical fluids in porous media, and more especially (3) during an innovative post-doctoral work (2007-2008) at MIT, on the development of classical microfluidic devices used under pressure and temperature. This last work has definitely shown the feasibility of our present ambitious project as far as technology is concerned. After about 24 months of the project, the three partners will make use of supercritical microfluidic devices, limited in number and in operating conditions, but well designed to support original characterization instrumentation, adapted to the main scientific challenges to be satisfied. When approaching the project ending, at 36 months, the four partners should reach their initial objective, providing the national scientific community with the main mandatory elements to use supercritical microfluidic devices on technological platforms. Some potential applications will then go on and develop in relation with interested industrial teams, more particularly the one initiated by the three partners during the third year of the project, dedicated to the verifications of the results from test and modelling experiments compared to numerical simulations.