Response Surface Based Optimization of an Electro-Thermal Microactuator for High Track Density Optical Disk Drives

Optical disk drives (ODD) have become one of the most popular solutions for large storage capacity applications and are widely used in consumer electronics. For precise positioning in optical disk drives (ODD), the actuating system using MEMS technology has been considered as a very promising solution. This paper aims to optimize a recently proposed microactuator design as a fine-tracking device for high-density ODD. The microactuator device is electrothermally driven and consists of suspended bimorph beams that are connected to electric heater through linkage hinges on a micromirror platform. Static and dynamic characteristics of the microactuator device are analyzed using coupled electrothermal-mechanical finite element models. Our modeling results reveal that the performance of the original design is undesirable as the central mirror platform is undergoing a lateral shift and is bent concave down when the microactuator is activated. In order to maintain the relative flatness of the mirror surface, a new design with a folded-arm structure is proposed. The design is further optimized using experimental design and response surface method to achieve large actuation displacement and improved resonant frequency response. Overall, the results show that the optimized design outperforms the original design in achieving large displacement, fairly small lateral shift and mirror flatness under the same actuating voltage, while maintaining a compact size and supporting the high bandwidth servo control.