Straight movement of micro containers based on ratchet mechanisms and electrostatic comb-drive actuators

This paper describes the design, simulation and fabrication of a micro conveyer system (MCS) with straight displacement of micro containers based on ratchet mechanisms and electrostatic comb-drive actuators. This MCS consists of linear comb actuators, micro containers and ratchet racks. The micro containers can be moved with different velocities by comb-drive actuators through ratchet teeth. In this study, a SOI wafer with a device layer of 30 mu m and a buried SiO2 layer of 4 mu m is used. Each module of the MCS has dimensions of 6 x 6 mm(2), is fabricated by using only one mask, ICP-RIE and vapor HF etching techniques, and can be assembled to create more complex conveyance systems for different applications, such as in bio-chemical analysis or a micro total analysis system (mu-TAS) to transport and classify small samples. In our experiments, the movement of the micro container has been tested with a driving frequency ranging from 5 Hz to 40 Hz. The velocity of the container was proportional to the frequency and matched very well with theoretical calculation.