A rotary microgripper with locking function via a ratchet mechanism

This paper presents a rotary microgripper with locking function enabled by a ratchet mechanism. The ratchet mechanism enables long-time gripping without having to continuously apply the external excitation signal such as the electrical, thermal or magnetic field. Thus the damage to the gripped micro-scale objects caused by the external excitation signals can be significantly reduced. A logic control strategy is proposed to solve the wearing problems of the ratchet mechanism. The stability of the microgripper is improved by increasing the length of the engaged line. The microgripper is fabricated by an improved silicon-on-insulator dicing-free process to protect the delicate device structure from damage during fabrication. The microgripper has a discrete opening range and can handle micro-scale objects with a size of 20 μm, 40 μm and 60 μm based on the current design parameters. A pick-lock-release gripping experiment on a magnolia pollen cell is performed to form a triangle to prove the feasibility of the gripper in handling biological cells.