Tactile image detection using a 1k-element silicon pressure sensor array

Abstract

A 32 × 32 (1k)-element silicon pressure sensor array with CMOS processing circuits has been fabricated for the detection of a high-resolution pressure distribution. The sensor array consists of an X – Y matrix organized array of pressure- sensing cells with a spacing of 250 μm; CMOS processing circuits are formed around the array on the same chip. Fabrication of the sensor array is carried out using a 3 μm CMOS process combined with, Si micromachining techniques. The diaphragm size is 50 μm × 50 μm square. The sensor array chip size is 10 mm × 10 mm. The main features of the design for the tactile image detector are the two-line readout system for a full bridge of piezoresistors in each individual cell for noise reduction, and the low power consumption array exciting system with n-MOS power switches selecting the X – Y address in large-scale sensor integration. A tactile image-detecting system is set up for indicating tactile images as visible pictures. The detecting system is provided with functions for signal amplification and offset cancellation. High-resolution tactile images are stably shown as two- or three-dimensional figures on the display through computer processing of the readout data.