A double-sided in-plane lateral comb-drive actuator fabricated by a plaster-based 3D-printer

In this paper, design, fabrication and characterization of a double-sided in-plane lateral comb-drive actuator fabricated by a plaster-based 3D-printer is described. The design is based on MEMS (Micro Electro-mechanical Systems) design concept. The movable part of the actuator consists of a (10x52.5) mm rectangular plate, and the end sides have depression areas in order to fit a (0.5x21.3) mm beam-shaped hinges. In the remaining sides of the plate, 18 comb fingers (0.5x10) mm are set at each opposite side. The stationary part of the actuator consists of 17 comb fingers with the same dimension to that of the stationary ones, and they are set at both sides of a frame and interdigitated with the movable comb fingers on the same plane. The gap between the movable and stationary comb fingers is 1.0mm. The structure thickness is 1.5mm. Such a structure, which both sides are provided with an in-plane interdigitated comb fingers, is called double-sided in-plane lateral comb-drive actuator. This actuator has been fabricated by using a plaster-based 3D-printer. Since plaster composite is an electrical insulating material, the structure has been suitably masked and the upper and lateral surfaces have been metallized thereafter by Au ion sputtering for the actuator electrodes formation. The hybrid fusion of 3D-printing manufacturing technology and MEMS-based design concept has been recently proposed by the authors and named as SMEMS (Sub-milli Electro-mechanical Systems), since the smallest possible fabrication size is in the order of sub-millimeters. The advantage of SMEMS technology is the quick and easy fabrication of 3D structures from 3D-CAD data. Furthermore, SMEMS is completely environment-clean since any hazardous chemicals or gases are used. The actuator has been driven by differential voltages, where both sides are biased at a voltage of 100V, and a 200 Vpp and its 180°shifted sinusoidal voltages are applied at each side. The actuator laterally moved by 96.8μm (full width) at a resonance frequency of 72Hz, and the mechanical quality factor has been estimated to be about 10.