Antenna-Like Tactile Sensor for Thin-Film Piezoelectric Micro-Robots

Terrestrial and other millimeter-scale autonomous micro-robots face significant challenges in surveying their environment, due to small power budgets and payload capacities. One low-power, low-mass form of obstacle detection is tactile sensing of contact with other surfaces. In this-paper, a tactile sensor inspired by insect antennae is described, based on thin-film lead-zirconate-titanate (PZT) transduction. Thin-film piezoelectric materials permit actuation and sensing mechanisms to be coupled in very small, compact structures, as well as complement previously developed microrobotic leg mechanisms. Key design parameters for the tactile sensor are introduced and analyzed in terms of sweep frequency and range of motion, and signals from sensor impact are predicted. Experimental results with partially-released prototype actuators show respectable agreement with modeled behavior for dynamic motion, though impact detection is hampered by large feedthrough disturbances. Completed sensors range from 2 to 4 mm in length and are approximately 500 μm in width, with a sweep range of nearly 1 mm demonstrated from a 2 mm long prototype.