Development of six-degree of freedom micro force sensor for application in geophysics

This paper presents the design concept, fabrication and calibration of a six-degree of freedom (6-DOF) turbulent flow micro sensor utilizing the piezoresistive effects in silicon. The proposed sensor can independently detect six components of force and moment on a test particle in a turbulent flow. By combining p-type conventional and shear piezoresistors in Si [111], and arranging them suitably on the sensing area, the total number of piezoresistors used in this sensing chip is only eighteen, much fewer than that of the prior art piezoresistive 6-DOF force sensors. Calibration for six components of force versus output voltages was completed. The sensitivities are linear close to the design values, and high enough to measure the forces and moments expected to act on the particles in turbulent flow in geophysics.