Subwavelength boundary-free acoustofluidic system

Microfluidics have been widely used to study microorganisms and manipulate their behavior in controlled microenvironments. However, conventional microchannels often reduce the throughput with high flow resistance and introduces high shear that can damage the cell membrane. As a promising alternative, acoustic tweezers offer gentle, contactless, label-free, and biocompatibility at high speeds. Here we present the acoustic-channeling of particles within the wide fluid chamber as a substitue for physical microchannel boundaries. The idea is demonstrated in both simulation and experiments with an ultrasound operating at 200 kHz structurally guided through the soft material. This approach creates a subwavelength acoustic tweezer capable of guidance, separation, and collection of the particles, expanding the capabilities of acoustic tweezer in biomedical applications.