Acoustically driven microfluidic devices based on hexagonal phononic crystal structures

This paper demonstrates a hexagonal phononic crystal structure based microfluidic device, which is actuated by surface acoustic waves, for centrifugation of micro particles in microliter droplet. In this work, the phononic structure interacts with the acoustic waves, providing reflection, scattering and diffraction, causes asymmetry on the propagation path. Thus, at the interface of the silicon and liquid, the acoustic waves could only be refracted into part of the droplet, and results in acoustic streaming in the droplet. Then, by recirculation, angular momentum will be induced within the sample drop and efficient centrifugation of micro particles could be performed. Advantages of this technique include fast manipulation speed, simple electrode structures, and wide actuating frequency range.