Shear sensitive silicon piezoresistive tactile sensor prototype

Shear sensing ability is important in many fields such as robotics, rehabilitation, teleoperation and human computer interfaces. A shear sensitive tactile sensor prototype is developed based on the principles of the piezoresistive effect in silicon, and using microfabrication technology. Analogous to the conventional silicon piezoresistive pressure sensor, piezoresistive resistors embedded in a silicon diaphragm are used to sense stress change. An additional mesa is fabricated on the top of the diaphragm and serves to transform an applied force to a stress. Both the shear and normal components of the force are resolved by measuring the resistance changes of the four resistors placed at the corners of a prism mesa. The prototype is tested both statically and dynamically when a spatial force of 0-300 gram is applied. Good linearity (R>0.98) and high repeatability are observed. In this paper, the force sensing mechanism and force determination approach are described. The fabrication process is presented. The preliminary testing results are presented and discussed. Keywords: silicon, sensor, tactile, shear, force, piezoresistive, resistor, mesa, diaphragm, microfabrication