Development of a Monolithic PMMA Comb-Drive Micro Actuator Utilizing Hot Embossing and Ultra-Precision Machining

This paper presents a novel fabrication process of monolithic PMMA comb-drive actuators utilizing hot embossing and ultra-precision machining. The robustness and capability of the method are demonstrated through the fabrication of sophisticated PMMA freestanding micro structures, such as lateral and vertical comb actuators, and a torsion micro mirror. Firstly, a silicon mold is fabricated by bulk micromachining technology. Next, comb-drive micro actuator structures are formed on PMMA plate by hot embossing. Then, the PMMA layer remained after hot embossing is removed by ultra-precision cutting to release the movable parts. Finally, the device is coated with a gold layer for the electrode. A monolithic PMMA lateral and vertical comb actuators with finger´s width, thickness, and gap between two fingers are 5 mum, 60 mum and 5 mum, respectively, have been fabricated and tested successfully.