Tactile Perception using Micro Force/Moment Sensor Embedded in Soft Fingertip

In this paper, we show a novel tactile sensor fabricated by embedding a micro-force/moment sensor inside a hemispherical soft fingertip, which is applicable to the object manipulation using robotic hands. This sensor is produced by MEMS technology, designed to detect one force component (Fz) and two moment components (Mx,My). The structure is composed of a central square-block and four crisscross beams across the block, and its dimension is 9 mm for a single sensing chip. We designed two types piezoresistors on the beams. One is a conventional two-terminal piezoresistor capable to measure a longitudinal strain, and the other is a four-terminal square-shaped piezoresistor capable to measure a transverse strain. We also applied a structural analysis to the chip to evaluate stress distribution on it. Finally, we show that Fz,Mx, and My measured by the electrical potential difference on each terminal have high accuracy and keep low fluctuation in compression test of the soft fingertip.