3D Acoustofluidics via Sub‐Wavelength Micro‐Resonators

Precise acoustic micromanipulation is emerging as an important tool in biomedical research, where acoustic forces have the advantage of being contact‐free, label‐free, and biocompatible. Conventional acoustofluidic approaches, however, produce device‐scale effects that limit the ability to locally target acoustic energies at the microscale. In this study, we demonstrate an approach to generate designed and highly local acoustic fields using 3D resonant mass‐spring microstructures, achieving local acoustic field gradients on the order of microns, orders of magnitude smaller than the fluid wavelength. In doing so, rapid and spatially defined controllable micromanipulation, including particle capture, transport, and patterning using arbitrarily arranged micro‐resonator arrays is demonstrated. This sub‐wavelength, 3D acoustofluidic approach results in highly localized and defined micromanipulation, with potential applications across sample preparation, cell analysis, and diagnostics.