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In this paper, a newly developed ultra-high resolution tactile sensor with a spatial resolution of 0.1µm and a force resolution of 60µN is reported for the first time. The ultrahigh resolution tactile sensor is required for quality control of finished metal surface and painted surface of automobiles that are not replaced by “non-contact” optical measurements. A 0.1µm spatial resolution is realized by a needle-like contactor-tip precisely formed by deep-RIE. A 60µN force resolution is realized by partly narrowed silicon spring. Also, piezoresistors were arranged to maximize the stress sensitivity considering the crystal orientation dependency on piezoresistive effect. The fabricated new device in this study has realized 6 times higher performance in vertical displacement and 40 times higher performance in frictional force resolution than the tactile sensor device that we reported in 2018 [1]. Measured surface shape corresponded well to the actual surface shape in deep sub-micron region.

This is the first report about “sense of touch in submicron region” realized by novel 2-axis tactile sensor with a needle-like contactor. Simultaneous detection of submicron surface shape and correlated minute frictional force is realized by 0.5μm-radius contactor tip and highly sensitive strain sensing part of the sensor. Furthermore, contacting the contactor tip to measuring sample surface at a 10° slant angle, one-point contact is realized, and the spatial resolution of tactile sensing has been drastically improved to submicron range.