Vertical contact position detection and grasping force monitoring for micro-gripper applications

A piezoresistive sensor for micro-grippers, capable of detecting the contact position of the micro-object along the vertical dimension of the grasping surface as well as the grasping force, has been developed and successfully tested. The integration of this sensor into micro-grippers would improve their reliability because the monitoring of the grasping position is fundamental in many micro-assembly tasks. The device is fabricated with an IC-compatible process and integrates two force sensors in a Wheatstone bridge configuration, whose outputs allow the computation of the contact position and the applied force. The sensors sensitivity is 16.9 V/N, with a supply of 1 V across the Wheatstone bridge. The maximum detectable contact force is up to 3 mN with an estimated resolution better than 1 ¿N. The resolution of the grasping position depends on the applied force. Results show that position with a resolution of 10 ¿m can be distinguished along the vertical direction of the grasping surface when a force of 1 mN is applied.