Chaotic mixing in electrokinetically and pressure driven micro flows

We present two micro-devices, fabricated by using MEMS technology, in which mixing of fluid and particles takes place. The systems are designed to induce folding and stretching of material lines, leading to chaotic-like mixing. In a first case, we use unsteady pressure perturbations superimposed to a mean stream, and in the second case, time-dependent dielectrophoretic forces to induce folding and stretching. The first device shows chaotic-like mixing is achieved in an efficient way, leading to rapidly homogenizing concentration fields. Folding and stretching effects inducing mixing are shown for the second system. The systems are simple in their conception and may favorably be integrated within complex bio-MEMS.