Investigation of the effect of chip material on acoustofluidic microparticle manipulation

Ultrasonic particle manipulation in microchannels is a rapidly growing research field with significant potential applications in biological studies. Several factors are essential in achieving effective manipulation, such as obtaining resonance conditions in the actuator, chip, and/or the microchannel. The choice of chip material is an important design parameter since it has significant implications on acoustic performance, thermal performance, stability, ease of manufacturing and the overall cost of the acoustofluidic separation unit. Even though different materials are employed in acoustofluidic studies, most studies implement silicon as the chip material due to its superior acoustic properties. On the other hand, silicon has a complicated manufacturing procedure that requires cleanroom facilities. Therefore, from the manufacturing perspective, it is beneficial to use materials that enable mechanical machining. In this study, for the first time in the literature, we have compared the performance of acoustofluidic chips manufactured from silicon, glass, PMMA (polymethyl methacrylate) and PDMS (polydimethylsiloxane) materials in a comparison study. Furthermore, we propose using a new composite material, FR4, which seems to possess favorable acoustic properties of acoustically hard materials (such as silicon and glass) and the ease of manufacturing of acoustically soft materials such as polymers.