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 µm 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.