Hardness detection using a micromachined active tactile sensor

We developed a new type of micromachined tactile sensor that detects both the contact force and hardness of an object. It consists of a diaphragm with a mesa structure, a piezo-resistive strain sensor on the diaphragm, and a chamber for pneumatic actuation. We theoretically designed the device specifications to detect humanfinger touch. We developed the fabrication process of the device using micromachining technology. The sensor element measures 6.0 mm /spl times/ 6.0 mm /spl times/ 0.4 mm. We experimentally evaluated the device characteristics by using silicone rubbers with different hardnesses as the model materials, and we verified the hardness detection performance. The fabricated tactile sensor detected differences in hardness in the range of 10/sup 3/ to 10/sup 5/ N/m.