Surface coupled locally resonant modes for reinforced and localized acoustofluidic particle manipulation

Acoustofluidics is an efficient, label-free, biocompatible, and low-cost technique for manipulating particles in biological and medical research. Despite its capabilities, challenges in complex patterning and bio-particle trapping remain. However, recent advances have improved the acoustofluidic manipulation flexibility by engineered spatially localized acoustic fields. This study proposes surface-coupled resonant modes using surface acoustic wave-driven ridges at 9.65 MHz within a conventional acoustofluidic channel for reinforced bio-particle manipulation. The amplified localized displacements at the resonating ridge edges and the consequent enhanced localized acoustic fields in the fluid lead to strong local vortices and enhanced acoustic forces in the ridge-included configuration, 2.2 (3.8) times higher than the conventional configuration according to the experiments (simulations). Moreover, the exerted reinforced acoustic forces have reduced the required electric input power to efficiently manipulate target particles in the ridge-included configuration compared with the conventional configuration. The ridge-induced reinforced acoustic forces are directed toward the ridge edges, hindering the target particles from being washed out. The introduced ridge-included acoustofluidic channel is raised as a promising platform for efficient, rapid, and engineerable manipulation of bioparticles, paving the way to attain tunable bioparticle manipulation in compact, low-power, and high-throughput lab-on-a-chip systems.