Acoustic black hole profiles for high-performance ultrasonic tweezers

Ultrasonic tweezers have provided significant capabilities for manipulating and handling objects in fluids across the fields of biomedical engineering, material preparation, micro/nano manufacturing, micro/nano robots, and so forth. However, most ultrasonic tweezers require precise design and professional operation, and an ultrasonic tweezer with more versatile, robust, and easy-to-use features is still scarce. In this study, through incorporating a one-dimensional acoustic black hole (ABH) structure, we propose and develop an innovative acoustic black hole tweezer (ABHT), which can easily realize multiple manipulation functionalities such as trapping of particles in various fluidic environments and cross-media extraction of particles. Numerical simulation results show that the ABH-enabled focused flexural waves at the tweezer’s tip can generate strong acoustofluidic effects including acoustic radiation forces on particles and acoustic streaming for particle trapping. We experimentally evaluate the performance of our ABHT, and also propose and demonstrate the topological device design with the high-throughput configurations. This work indicates that besides the conventional vibro-acoustic applications such as vibration mitigation and energy harvesting, ABHs can also play an effective role in ultrasonic particle manipulation devices. We believe the employment of ABHs would spur the emergence of more novel and useful ultrasonic particle manipulation and acoustofluidic devices in the future.