Stretchable and soft electroadhesion and capacitive sensors enabled by spider web-inspired interdigitated liquid metal subsurface microwires

Stretchable and soft electronic devices with the ability to sense objects and adhere to surfaces, similar to spider webs, are promising for creating soft robotic systems. In this study, stretchable and soft devices mimicking the features of a spider web were developed by utilizing interdigitated electrode subsurface microwires patterned on PDMS (Polydimethylsiloxane) elastic substrates. The devices could generate electroadhesion to surfaces through an out-of-plane electric field generated from in-plane interdigitated electrodes. Such interdigitated electrodes patterned on dielectric PDMS substrates could also generate capacitance owing to the electric charge stored on these electrodes due to the potential difference generated between them. To form interdigitated electrodes patterned in PDMS substrates, we used the liquid metal (EGaIn, eutectic gallium-indium), which was a soft and fluid conductor. Therefore, the device could maintain its electroadhesion performance while being strained and capacitance could be manipulated by the interference of the fringe electric field, thereby sensing external objects by distinguishing their proximity, contact, and pressure. These unique properties of the devices mimicking the features of a spider web can be utilized for fabricating soft robots, grippers, and electronic skin.