Developing Ionoelastomer Heterojunctions for Low-Voltage Electroadhesion

Our group has recently reported the use of heterojunctions between oppositely-charged ‘ionoelastomers’, i.e., low glass-transition polyelectrolyte networks, for a number of electromechanically responsive devices. In particular, they offer promise as low-voltage reversibly switchable electroadhesives, with potential applications including in soft robotics. Because voltages applied in reverse bias are dropped largely across the nanometer-scale ionic double layer formed at the interface between the two layers, large Maxwell stresses and corresponding enhancements in adhesion can be generated using applied potentials of < 10 V, in contrast to the kV levels generally required for established electroadhesives based on dielectric layers. We have focused tuning the composition of the ionoelastomer layers to lower their surface energy and improve the contrast between ‘on’ and ‘off’ state adhesion, in addition to improving their ionic conductivity. By considering the design of the ionoelastomer/electrode interface, the effects of surface topography, and the geometry of the adhesive pads, we have achieved electroadhesive clutches that support higher forces per unit area than previous dielectric-based systems, while operating at two orders of magnitude lower potential.