Multifunctional electroelastomer rolls and their application for biomimetic walking robots

Electroelastomers (also called dielectric elastomer artificial muscles) have been shown to exhibit excellent performance in a variety of actuator configurations, but making a compact, free-standing, muscle-like actuator capable of obtaining good performance has been a challenge. By rolling highly prestrained electroelastomer films around a compression spring, we have demonstrated Multifunctional Electroelastomer Rolls (MERs) that combine load bearing, actuation, and sensing functions. The MER spring rolls are compact, have a potentially high electroelastomer-to-structure weight ratio, and can be configured to actuate in several ways, including axial extension, bending, and as multiple degree-of-freedom actuators that combine both extension and bending. One degree-of-freedom (1-DOF), 2-DOF, and 3-DOF MERs have all been demonstrated through suitable electrode patterning on a single monolithic substrate. A 1-DOF MER with 9.6 g weight, 12 mm diameter, and 65 mm total length can deliver up to 15 N force and 12 mm stroke. Its capacitance is around 13 nF and changes linearly with strain during axial tension or compression. The MERs are useful in a number of applications where compact and high-stroke actuation is required. The applications as artificial muscles are particularly appealing, as multifunctionality prevails in natural muscles.