Vision-Based Closed-Loop Control With Spatiotemporal Multiplexing Strategy for Noncontact Trapping of Multiple Micro-Particles

Noncontact trapping of micro objects has great application potential in fields like material science and biomedical engineering due to its label-freeness and biocompatibility. In this paper, an automated acoustic micro-particle trapping system implemented with phased transducer array (PTA) is prototyped. The system is incorporated with a stereo vision to provide visual feedback benefited from localization of the invisible acoustic field through hydrophone scanning. Binocular vision calibration and stereo matching are realized using image Jacobian matrix. An efficient phase modulation algorithm is proposed for the calculation of desired PTA phase profile in real-time and a spatiotemporal multiplexing control strategy is adopted to dynamically generate multiple trappings. Experimental results well demonstrated that the stable trapping of multiple particles can be robustly realized by the system, leading to the improvements of robotic noncontact manipulation with invisible acoustic end-effector.