ON THE RESPONSE-TIME BEHAVIOR OF LASER MICROMACHINED NITI SHAPE-MEMORY ACTUATORS

The response-time behaviour of NiTi shape memory actuators fabricated by laser micromachining has been studied with experimental methods. A numerical model to determine the scaling laws of the characteristic re sponse time with decreasing volume of these types of actuators has bee n set up. With this new approach a finite-element (FE) model has been developed on the basis of measured data of the thermal conductivity, h eat capacity and electrical resistivity as a function of temperature. The results of the simulation, verified by measured data, show that mi niaturization, i.e., scaling down the volume, of the actuator can stro ngly improve the response time and consequently its switching speed. T he influence of the parameters that determine the actuation and reset response time of micron-sized shape memory actuators, like the thermal hysteresis and the actuator volume, can be quantitatively predicted.