A Sidewall Piezoresistive Force Sensor Used in a MEMS Gripper

This work reports the design and development of a MEMS based, piezoresistive sensor for micro-force measurement. Surface and bulk micromachining technology is employed to fabricate the force sensor from single crystal silicon wafer (i.e., no silicon on insulator wafer is used). Boron diffusion process combined with deep reactive ionic etching (DRIE) technique is used to form the side direction force sensors. The force sensor is integrated in a four arms structure MEMS gripper to experimentally verify the performance of the sensor. The resolution of the force sensor is in the micronewton range and, therefore, provides feedback of the forces that dominate the micromanipulation processes. Testing results show that the sensitivity of the piezoresistive sensors is better than 72V/N and the resolution is better than 3μN. Experimental show that it can successfully provide force sensing and play a main role in preventing damage of microparts in micromanipulation and microassembly tasks.