Multi-particle acoustic manipulation on a Chladni plate

Controlling the motion of multiple miniature objects independently and simultaneously is a grand challenge in microrobotics. In this paper, we report our recent achievements in acoustic manipulation that can control the motion of multiple objects simultaneously and independently on a centrally actuated vibrating plate. By employing spatially highly nonlinear excitation fields on the plate, we can control the motion of multiple objects with relaxed properties. The paper reports the modelling of the excitation fields, open-loop control based on pre-calculated control sequence, and closed loop control using model predictive control (MPC) and linear programming methods. The experimental results show that with appropriate planning, object motion on vibrating plate is sufficiently predictable to be controlled even in open-loop. The experimental results with closed-loop control show that the methods allow various applications including trajectory following, particle assembling, and droplet merging. Despite the reported method is based on acoustic manipulation on a Chladni plate, the method can be extended to other energy fields as soon as they are spatially highly nonlinear and such nonlinearity can be excited.