Freely Assembled Multifunctional Acoustofluidic Devices Based on Flexible Printed Circuit Boards

Surface acoustic wave (SAW)-based acoustofluidics has shown great potential for manipulating micro- and nanoparticles, enabling applications such as acoustic centrifugation and particle patterning. However, conventional SAW devices fabricated through photolithography and metal deposition suffer from long processing times and lack structural tunability after fabrication. In this study, a functionally tunable acoustofluidic device based on a flexible printed circuit board (FPCB) is proposed. By mechanically clamping interdigital electrodes (IDEs) on the FPCB to a piezoelectric substrate and incorporating an impedance-matching network, efficient SAW excitation is achieved. The device enables rapid enrichment of polystyrene (PS) particles ranging from 500 nm to 5 $\mu $ m. Moreover, controlled patterning of 10 $\mu $ m particles is realized using a magnetically attached rotating fixture, which adjusts the acoustic wave propagation direction on the substrate to excite different acoustic modes. This modular and reconfigurable FPCB-SAW device offers an adaptable platform for rapid functional validation of SAW systems and facilitates broader applications of acoustofluidic technology.