Phononic Microstructures in Microfluidics
Abstract: Surface acoustic wave (SAW)-based microfluidics, briefly acoustofluidics, has been drawing increasing attention to manipulate micro- or nano-particles as a versatile, biocompatible, low-power consuming and practical means. Usually, Rayleigh SAWs generated by inter-digital transducers (IDTs) on piezoelectric substrates are prefferred in acoustofluidics to trap, translate or separate particles in a microfluidic channel. However, spatial distribution of generated SAWs depends fundamentally on IDT design, which limits the applicability and compactness of acoustofluidic devices. Phononic crystals (PnCs) are artificial periodic structures for manipulation of acoustic or elastic waves. With geometrical details on the order of wavelength, piezoelectric PnCs may possess localized resonances and band gaps for SAWs, making them excellent candidates to steer waves with small footprint. In this seminar, I will introduce our work on employing phononic crystals in acoustofluidics for nanoparticle manipulation. We are especially interested in obtaining highly-focused SAWs and Bessel beams for size-based nanoparticle separation. Incorporation of piezoelectric PnCs in acoustophoretic systems can leverage the design of multi-tasking, high-throughput, paralel-processing compact microfluidic devices.