Strategies of stable grasp and accurate release for dual-finger micromanipulator

In microscale, adhesion force enables us to grasp targets with only one end-effector. However, due to the vibration of the driving unit and the environmental disturbance, losing target often happens during the grasp. The adhesion also makes releasing the targets from the end-effector difficult, and release accuracy cannot be guaranteed. In this paper, we proposed novel strategies of grasp and release for a dual-finger micromanipulator. The dual-finger micromanipulator includes two micropipettes as the end-effectors. One micropipette is fixed and the other active micropipette is actuated by a piezo-driven 3-DOF parallel mechanism. Tips of the micropipettes are heated to form spherical tips, then the tips are grinded to form hemispherical shapes. The big flat surfaces of the hemispherical end-effectors can increase the success rate of the grasp and avoid the target lose. In the release strategy, the hemispherical tip of the active micropipette is coated with gel to keep the target always sticking on the tip of active micropipette. Then, the active pipette is controlled to vibrate, and release the target adhered on its tip.