Hybrid micro-meso mechanical switch array for tactile displays

Traditional MEMS actuators have limited stroke and force characteristics. This paper describes the development of a novel hybrid actuation solution, which utilizes a micromachined actuator array to provide switching of mechanical motion of a larger meso-scale piezo-electric actuator. One motivating application of this technology is the development of a tactile display, where discrete mechanical actuators apply vibratory excitation at discrete locations on the skin. Specifically, this paper describes the development fabrication and characterization of a 4 × 5 micro-actuator array of individual vibrating pixels for fingertip tactile communication. The individual pixels are turned ON and OFF by pairs of microscopic thermal actuators, while the main vibration is generated by a vibrating piezo-electric plate. A thermo-electric and non-linear thermo-elastic models have been developed to account for the temperature dependence of the electrical resistance and the lateral buckling of the hot, respectively. Comparison between analytical and finite element models indicated very good agreement, confirming that the buckling of the hot arm has most significant impact in the overall actuator performance. The fabrication sequence and the actuation performance of the array are also presented.