RF-activated surface standing acoustic wave for on-chip controllably aligning of bio-microparticles

Surface Acoustic Wave (SAW) has emerged as a powerful technique for kinds of application, such as gas sensor, on-chip manipulation of microparticles or biological cells. In this paper, we present a numerical simulation and experimental study of standing surface acoustic wave (SSAW) induced acoustophoresis to assemble the particle samples in a microchannel. The simulation of the SAW is implemented by coupling the Maxwell equation and Newton equation. Once the acoustic wave along the piezosubstrate surface is obtained, the acoustophoresis force induced by surface standing acoustic wave (SSAW) is able to be derived. The SSAW generated by two parallel interdigital transducers (IDTs) which are excited by the radio frequency signal induce the acoustic radiation force to propel particles toward the pressure node. The assembling time also can be tunable by controlling the applied RF power. The numerical model and the experiment result can provide the critical guidance for the design of focusing component by SSAW which can significantly benefit the development of future on-chip flow cytometry.