Durability of Silicon Pin-Joints for Microrobotics

This work presents the initial characterization of planar silicon pin-joints for use in linkages for walking micro-robot legs. A major goal in walking microrobotics is the creation of robust leg structures driven by low-power motors capable of lifting a 20mg mass and propelling it forward. Hinged joint structures, rather than stiff flexures, are ideal for this task. However, since joints are not fully rigid structures, the possibility of pull-out failure is important to take into account. The joints we use are fabricated in a silicon-on-insulator (SOI) process. They have demonstrated pull-out forces ranging from 1mN to 29mN, well over the strength of our motor designs and capable of handling the intended mass of the robot. Additionally, the frictional coefficient during pull-out was found to be dependent on the load from the joint holder.