MEAM Seminar: “High-performance Electroadhesives for Materials and Robots with Programmable Stiffness”

Materials with electroprogrammable stiffness and adhesion can enhance the performance of robotic systems but achieving large changes in stiffness and adhesive forces in real time is an ongoing challenge. Electroadhesive clutches can rapidly adhere high stiffness elements, although their low force capacities, high activation voltages, and inability to separate and turn off stiffness changes reliably have limited their applications. A major challenge in realizing stronger electroadhesive clutches is that current parallel-plate models poorly predict clutch force capacity and cannot be used to design better devices. Furthermore, soft material interfaces have not been utilized for stronger electroadhesive clutches due to latent adhesion at the contact interface that prevents programmable release.

In this talk, a fracture mechanics framework to understand the relationship between clutch design, force capacity and contact area is discussed. This mechanics-based framework predicts clutch performance across multiple geometries and applied voltages. Based on this approach, a Coulombic electrostatic clutch with 94 times the force capacity per unit electrostatic force of state-of-the-art electroadhesive clutches is realized. These electroadhesive clutches are used to increase the load capacity of a soft, pneumatic finger by a factor of 62 times compared to a finger without an electroadhesive. Finally, this mechanics-based design methodology is applied to the design of low-voltage ionoelastomer clutches with soft material interfaces for wearable robotic applications with increased force capacities and programmable release at reduced device sizes.