Design of a Hybrid Magnetic and Piezoelectric Polymer Microactuator

Microsensors and microactuators are considered to be the most crucial elements of micro-electromechanical systems (MEMS) and devices. There has been growing interest in the development of new microactuator technologies with an increasing requirement for low cost microswitch arrays providing large air gap and large force at the same time. In particular, large air gap/large force microactuators are essential for high voltage switching in automobile electronics, test equipment switchboards and in network remote reconfiguration. The necessity to reduce the size of actuators and at the same time increase the force and the air gap has placed severe constraints on the suitability of current microactuator technology for various applications. This has led to the development of new actuator technologies based on novel materials or modifying existing systems. As an effort in this direction, this thesis presents the details of the work on the design, fabrication and testing of a new hybrid microactuator, combining electromagnetic and piezoelectric actuation mechanisms. The design and fabrication of electromagnetic actuators using planar coils and a soft magnetic core has long been established. However, in many instances these designs are constrained by difficulties in the fabrication of the multi layer planar coils, which is tedious, often resulting in a low yield. Hence device performance is limited by the maximum coil currents and thereby the maximum force able to be generated. In order to overcome these problems, a hybrid actuator combining the electromagnetic system along side of a piezoelectric actuation is proposed. This has been demonstrated to assist in enhancing the total force and consequently achieving larger actuator displacements. In this research a hybrid microactuator with a footprint of 10 mm was designed, fabricated and tested. It can generate 330 μN force and cover 100 μm air gap as a microswitch.