Mixing, Trapping, and Ejection of Single Microparticle with Size and Material Selectivity Using Acoustic Tweezers

This paper presents the mixing, trapping, and ejection of a single microparticle based on an acoustic tweezers. Finite Element Model (FEM) simulation, along with analytical modeling, is used to study the selectivity of particles based on size and material properties. The acoustic tweezers is optimized to have a single trapping zone, where particles are trapped due to acoustic radiation force (which is calculated for particle sizes exceeding the Rayleigh approximation). The tweezers is experimentally shown to lift microparticles from the tweezers surface, selectively trap a single particle based on size and material acoustic properties, and then eject it upwards for collection. All these are obtained with negligible heat generation.