Gecko-inspired adhesion enhanced by electroadhesive forces

Soft robotic manipulators have been increasingly adopted over the last decade due to theirpassive conformation to the shapes of objects, which can reduce control complexity. Theperformance of these grippers can be improved using flexible adhesive skins that increase tactilegripping forces, which is particularly important when grasping delicate objects and flexiblesubstrates that are otherwise difficult to manipulate. In this work, we investigate how passivegecko-inspired fibrillar adhesion can be augmented by actively controlled electroadhesion (EA).The passive gecko-inspired skin (GS) enables adhesion with no power consumption while EA iscontrolled with an applied voltage. We have shown how the microstructures in a gecko-inspiredadhesive skin affect EA by using numerical simulation to quantify how they influence thelocalized EA field strength. The results show that the microstructures cause a highlynon-uniform distribution of electric field strength generate and hence the EA force distributionis inhomogeneous. Overall, it was found that the dielectric properties of the gecko-inspired skinreduce the magnitude of field intensity on the adhesive contact surface by only 2.1% at 3 kV. Itis experimentally determined that when compared with GS alone, EA with gecko-inspired skinincreases the shear force by 66.8% and the normal force by 53.7% with an applied voltage of4 kV. It is shown that the gecko skin’s adhesion force is enhanced by increased engagement ofthe fibrillar microstructure to object surfaces due to EA. The increased contact engagement isexperimentally demonstrated using frustrated total internal reflection imaging. This work showsthat electroadhesive-enhanced gecko-inspired skin generates a greater adhesive force than thesum of forces from the separate gecko-inspired skin and EA. In this way, electricallycontrollable and passive adhesion mechanisms can be combined to improve the handling offlexible and delicate objects with smooth or rough surfaces.