| Force feedback is an important feature in most microgripper applications, but it is commonly overlooked. To successfully implement this feature, a cantilever structure has been designed and fabricated to integrate force feedback into a microhand gripper. The piezoresistive properties of doped polysilicon are used to transduce the mechanical stress of an object pressing against the cantilever sensor, resulting in a change in resistance or voltage capable of being monitored with external hardware. The force sensing structure was designed to have a fabrication process compatible with that of the microhand, allowing for their eventual integration. This fabrication process uses both bulk and surface micromachining techniques to create the cantilever structure, a balloon actuator (utilized in the microhand), and the interconnect to interact with both the electrical sensors and the pneumatic actuators. The prototype fabrication successfully defined the majority of the MEMS device with the exception of the final step. The release of the cantilever failed due to underetching of the entire device rather than just the cantilever, which was desired. Recommendations to solve this problem and improve the fabrication process are presented. |
