Two simple micromixers based on silicon

This paper reports modelling, fabrication and testing of two micromixers, The principle of mixing used for the devices was diffusion because of the small value of the Reynolds number in microcapillaries. The first mixer separates the main flow into partial flows, which are laterally alternated in order to increase the boundary surface between the liquids. The second mixer superposes two fluids by injection of one liquid into the other. The fabrication technology is based on etching of silicon and anodically bonding with Pyrex glass. The performance of the mixers has been verified by mixing phenolphthalein solution and ammonia dissolved in water. Reasonable mixing was achieved at pressures of around 4 kPa (lateral mixing) and 7 kPa (vertical mixing) with flow rates of approximately 1 mu l min(-1). The measurements were compared with diffusive mixing simulations with a CFD simulator and agreement of both was observed.