In this paper, a novel concept of silicon-microelectromechanical system tactile image sensor aimed at fingertip tactile applications and evaluation results of a prototype device are presented. Array of strain-sensitive sensor pixels is integrated on a pneumatically swollen silicon diaphragm with signal processing circuits in monolithic configuration. Elastic surface of the tactile image sensor is realized using repulsive force of the air pressure
applied to diaphragm backside. Contact force distribution of an object is detected from the stress distribution change on the diaphragm using piezoresistor array. Force range and force sensitivity can be controlled by the pressure even after device packaging step. In this principle, fine pitch of pixels and a largescale sensing array can be easily realized using the abilities of silicon CMOS technology. In addition, the movable stroke of sensor surface can be made much longer than the individually formed micromechanical pixels. A prototype device, of the new