Interfaceless Strain and Pressure‐Sensitive Stretchable Capacitor Based on Self‐Bonding and Surface Morphology Control of a Reversibly Crosslinkable Silicone Elastomer

Abstract A typical capacitive mechanical sensor implemented using a layer of soft dielectric polymer sandwiched between two flexible electrodes, where the capacitance is formed, suffers from unintended buckling instability upon repeated stretch‐and‐release owing to different mechanical characteristics of constituent materials and unstable interfaces. Here, a stretchable, healable, and transparent strain/pressure‐sensitive capacitor is successfully fabricated by hybridizing Ag nanowires (AgNWs) with a polydimethylsiloxane containing maleimide‐derived Diels–Alder (DA) adducts as reversible crosslinkers. AgNWs formed on the surface of the cured polymer sheet are impregnated under the surface of the film by utilizing the vaporized solvent‐assisted retro‐DA reaction. Two identical films with fully impregnated AgNWs under the polymer surface are subjected to lamination with the insulated areas facing each other to implement a sandwich‐structure with a centering dielectric layer. Owing to the retro‐DA and reversible crosslinking during heating, two films in contact are fully integrated as if the architecture is originally made of a single film. The sensitivity to pressure under the stretching condition increases by about 320% compared to that without stretching.