An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer...http://www.google.ca/patents/US7942568?utm_source=gb-gplus-sharePatent US7942568 - Active micromixer using surface acoustic wave streaming
