Acoustohydrodynamic tweezers via spatial arrangement of streaming vortices

Acoustics-based tweezers provide a unique toolset for contactless, label-free, and precise manipulation of bio-particles and bioanalytes. Most acoustic tweezers rely on acoustic radiation forces; however, the accompanying acoustic streaming often generates unpredictable effects due to its nonlinear nature and high sensitivity to the three-dimensional boundary conditions. Here, we demonstrate acoustohydrodynamic tweezers, which generate stable, symmetric pairs of vortices to create hydrodynamic traps for object manipulation. These stable vortices enable predictable control of a flow field, which translates into controlled motion of droplets or particles on the operating surface. We built a programmable droplet-handling platform to demonstrate the basic functions of planar-omnidirectional droplet transport, merging droplets, and in situ mixing via a sequential cascade of biochemical reactions. Our acoustohydrodynamic tweezers enables improved control of acoustic streaming and demonstrates a previously unidentified method for contact-free manipulation of bioanalytes and digitalized liquid handling based on a compact and scalable functional unit.

Automated summary

Acoustohydrodynamic tweezers present a novel method for contact-free manipulation of bioanalytes by generating stable vortex pairs to create hydrodynamic traps for object manipulation. This technology allows for predictable control of flow fields and precise handling of droplets or particles, showcasing improved control over acoustic streaming and digitalized liquid handling.