A tactile microgripper for application in microrobotics

As a part of a microrobot we present a micromachined gripper system which has both force sensor and actuator integrated. This gripper is used for handling and assembling and allows to control the gap of the gripper and the gripping force continuously. We use a thermal bimorph actuator for the operation of the gripper. For the force sensor we utilize the piezoresistive effect, known to be very strong in silicon. As compared to previous realizations we have optimized the design: the proposed folded bimorph beam delivers a multiple of the actuators stroke as compared to a simple beam structure. This folded bimorph beam design can also be applied to other bimorph actuators (e.g. piezoelectric, SMA). The actuators maximum stroke is 800 mu m at a finger length of 1600 mu m and the maximum force generated is in the order of 1mN. That means an improvement of a factor of five with respect to designs published earlier. The sensitivity of the sensor finger is about 100mV/VmN which is an improvement by a factor of three and it shows a good linearity.