Numerical simulation of acoustic streaming on surface acoustic wave-driven biochips

A novel type of microfluidic biochip employs acoustic surface waves as a pumping mechanism for fluids. Piezoelectric substrate materials in the chip efficiently convert an electromagnetic input signal into an elastic wave confined to the surface layer of the substrate, hence the surface acoustic wave. The interaction of these waves with an adjoining fluid volume leads to streaming patterns in the fluid or of the motion of the fluid as a whole. In this work we study this acoustic streaming effect. We present a two-scale mathematical model, some theoretical results on the well-posedness of the model problem, as well as numerical simulations based on the finite element method. The model will include the case of free capillary fluid boundaries.