HYBRID INTEGRATION OF A SHAPE MEMORY ALLOY ACTUATOR FOR MICRO THERMAL MECHANICAL SYSTEMS

This paper reports on the hybrid integration of a shape memory alloy (SMA) wire into a micromechanical structure to form a thermal drive system with advanced performance. The SMA wire is utilized as a bending actuator driving a suspended shuttle. This approach allows a cyclic movement with large displacements and forces. Depending on the temperature and the mechanical boundary conditions, the actuator provides maximum displacements of 160 mu m and maximum forces of about 120 mN. Displacement and force of the drive system are adjustable by design of the return spring stiffness and a geometry-defined offset. The influence of spring stiffness, offset and temperature load on the actuator performance is presented. The proposed actuator system enables new applications, for example chip-based energy autonomous detection and counting of thermal thresholds.