Microgripping force measuring device based on SU-8 microcantilever sensor

For the direct measurement of microgripper gripping force and the calibration of microgripper jaw stiffness, this paper presents a new microforce measuring device based on low-cost SU-8 microcantilever sensors with integrated copper piezoresistive strain gauge. On the basis of the deduced equations, the geometric parameters of the microcantilever sensor are determined. Then, the fabrication of the sensors is carried out using a simple process. One fabricated sensor is calibrated by measuring the output voltage and the applied vertical force simultaneously. The calibration result of the microcantilever stiffness is 2.99 N/m and the output sensitivity is 0.51 V/N. The performance test results of the calibrated sensor show that the force sensing range is 405 mu N and the maximum nonlinearity is 11 mu N. Finally, the microgripping forces of two different microgrippers are measured by the developed device, and jaw stiffness calibrations are also carried out. According to the experiment results, the normally closed SU-8 microgripper has a jaw stiffness of similar to 2.83 N/m and the jaw stiffness of the normally open SU-8 microgripper is similar to 7.22 N/m. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)