6 DOF Force and Torque Sensor for Micro-manipulation Applications

This paper presents the design, fabrication and characterization of a piezoresistive 6 Degrees of Freedom (DOF) force and torque sensor to be used in micro-manipulation. The mechanical structure of the device consists of 7 suspended beams and a calibration structure, which can be replaced by micro-manipulation tools such as micro-grippers or probes. The geometry of the beams and the location of the piezoresistors in the structure are optimized to reduce crosstalk and improve the sensitivity. A linear regression model is fitted to the calibration data to exxtract the forces and torques from the resistance variations detected in the piezoresistors. The device has been fabricated with an IC-compatible process and successfully characterized. The data acquisition system is programmable, allowing for dynamic adjustments of the trade-offs between noise levels, accuracy and bandwidth. Depending on the axis, the linear range of the sensor reaches 4 to 30mN in forces and 4 to 50 uNm in torques. During calibration, root mean square errors up to 17 to 45 μN and 14 to 40 uNmm were observed in the measured data, respectively.