Experimental Realization of Topological On-Chip Acoustic Tweezers
Hongqing Dai, Linbo Liu, Baizhan Xia, Dejie Yu
Abstract
Acoustic tweezers are gaining increasing attention due to their excellent biological compatibility. Recently, the concept of topology has been expanded from condensed-matter physics into acoustics, giving rise to robust wave manipulation against various defects. So far, topological acoustics have not been experimentally realized at an on-chip level to act as tweezers for microparticle manipulations. Here, we achieve topological on-chip acoustic tweezers based on the topologically protected phononic mode. These tweezers consist of one-dimensional arrays of Helmholtz resonant air cavities. Strong microfluidic oscillations induced by acoustic waves are experimentally observed at water-air surfaces of Helmholtz resonant air cavities at the topological interface. Acoustic radiation forces and streaming induced by these microfluidic oscillations capture microparticles, the sizes of which are up to 20 \textmu{}m, and make them undergo orbital rotations. Our topological on-chip acoustic tweezers realize noncontact label-free microparticle manipulations in microfluidics and exhibit enormous application potential in the biomedical field.