Silicon smart tactile image sensor with pneumatically swollen single diaphragm structure

In this paper, a novel silicon tactile image sensor with single diaphragm structure is presented. This tactile sensor has a tactile sensing region of silicon diaphragm on which two-dimensional (2-D) piezoresistor array for tactile imaging is integrated. Surface shape of touching object can be detected from stress distribution on the deformed diaphragm. MOS signal processing circuitry is also integrated around the diaphragm monolithically. The diaphragm region is pneumatically swollen by air-pressure to obtain a long mechanical stroke for tactile sensing. In addition, mechanical stiffness of the sensing region can be controlled by the pressure after device fabrication. If the pressure is adaptively controlled for amplitude of input, dynamic range of the tactile sensor will be much improved. As a result of device fabrication and evaluation, shape and position of a contacting plastic tip were successfully detected. Force sensitivity of piezoresistors was also controlled by the diaphragm pressure. This tactile image sensor is very promising to detect surface shape of 3-D object like human fingertips.