Multimodule Micro Transportation System Based on Electrostatic Comb-Drive Actuator and Ratchet Mechanism

We present a novel multimodule micro transportation system (MTS), which can drive micro containers in straight, curved, and T-junction paths based on electrostatic comb-drive actuator and ratchet mechanism. The transported objects are micro containers, which have two pairs of driving wings and anti-reverse wings attached to a body. Their movement is like a water strider, i.e., its driving wings rotate backward to generate reaction force to push the containers forward, while the anti-reverse wings act as a ratchet mechanism to prevent the container from moving backward. By developing three basic modules, i.e., straight, turning, and T-junction modules, the different configurations of the MTS can be built from these modules conveniently. Each module consists of ratchet racks driven by electrostatic comb-drive actuators. Containers having length, width, and thickness of 500, 250, and 30 μm, respectively, were driven to move with a changeable velocity up to 1000 μm/sec in straight, turning, and T-junction modules. The velocity of the container was proportional to the frequency of driving voltage. By utilizing silicon micromachining technology, a prototype of MTS was fabricated from silicon-on-insulator wafer with only one mask.