Electroadhesives made out of flexible contact layer (e.g., polyimide) and metallic thin film electrodes 8, 13 can generate robust electroadhesion on flat, smooth surfaces, but fail to accommodate free-form or rough surfaces, and lack the elasticity to integrate with fully soft-bodied robots.

Existing device-level electroadhesives are commonly operated under a few kilovolts to generate sufficient adhesive force, and have limited materials selection to fabricate with. However, incorporating electroadhesion into soft robotic bodies remains challenging. 1a) offers an alternative approach that is mechanically simple, lightweight, and easily switchable between engagement and release, thus have been utilized in recent robotic prototypes for anti-gravity locomotion 4, 5, 6, aerial perching 7, and fragile object handling 8, 9, 10, 11, 12 (Table 1). Bioinspired gecko-adhesion 1, 2, 3 employs micro- or nanoscopic artificial setae array to produce Van der Waals interaction for universal adhesion, yet it is mechanically complicated to mimic a gecko’s toe-pad motion to adhere and detach these adhesives. Soft robots empowered with controllable adhesives can benefit from astrictive, tunable, and reversible interfacial attraction to achieve unconventional robotic functionalities. Our materials and iontronic mechanisms pave the way for future advancement in adhesive-enhanced multifunctional soft devices. The grippers can capture soft and deformable items, bear high payload under reduced voltage input, and rapidly release foreign objects in contrast to electroadhesives. Iontronic soft grippers that seamlessly integrate actuation, adhesive prehension, and exteroceptive sensation are devised via additive manufacturing. Through supramolecular design and synthesis, the dual-material system exhibits cohesive heterolayer bonding and autonomous self-healing from damages. We present herein an iontronic adhesive based on a dynamically crosslinked gel-elastomer system, including an ionic organohydrogel as adhesive electrodes and a resilient polyurethane with high electrostatic energy density as dielectric layers. However, the lack of suitable conductive/dielectric materials and processing capabilities have impeded the integration of electroadhesive modules into soft robots requiring both mechanical compliance and robustness. Electroadhesion provides a promising route to augment robotic functionalities with continuous, astrictive, and reversible adhesion force.

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