MEMS Bimorph Fiber-Gripping Actuators

We investigate mechanical tangling for adhesion of microelectromechanical systems (MEMS) to unconventional carrier materials in the assembly of stretchable electronics. Adhesion plays a crucial role in fabrication, but is a difficult task to realize even on continuous thin films of soft materials like silicone and polyimide. Adhesion becomes more challenging on discontinuous surfaces like fabric meshes, yet these substrates expand the MEMS universe to new materials, and provide new affordances like passage of electronic contacts from one side of a mesh to the other. Microgripper arrays are realized by microfabrication and release of strained metal-oxide bilayers. This paper describes a process that wraps a MEMS gripper around a conductive fiber and reverses the process using electric current to open the gripper. The gripper’s electrical resistance serves as a self-temperature sensor over the 20-500 °C range. Beyond their potential for adhering MEMS to fabrics and to flexible/stretchable substrates that are incompatible with or resistant to adhesives, these microgrippers illustrate how MEMS-based microrobots might interact with small-scale (<200 micron diameter) fibers in manipulation and locomotion activities. The key contribution of this paper over our earlier work is demonstrating the grippers’ temperature-dependent resistance, which offers a route to improved control of the gripper state.