Quad-axial piezoresistive force sensor probe by four sensing elements with sidewall doping method

This paper reports a quad-axial force sensor probe which can measure tri-axial forces and one torque around the probe. By forming piezoresistors three dimensionally on the probe supporting beams, four sensing element can detect quad-axial force/torque on the probe tip. We demonstrated that the fabricated sensor had condition number of 2.6 with force resolutions under 1.0 μN and torque resolution under 1.0 nNm.