Ultrareproducible Capacitive Soft Pressure Sensor Using a Self‐Integrated Fibrous Network of Urethane Equipped with Diels–Alder Adducts

A pressure sensor based on a composite structure comprising air and polymer fibers is suggested to develop a capacitive pressure sensor that is virtually unaffected by repeated pressurization. Reversibly cross‐linkable urethane (RCU) derived from polybutadiene is newly synthesized for electrospinning, which exhibits the Diels–Alder (DA) reaction under mild conditions. RCU‐based microfibril film is fabricated and it succeeds in welding the intersections of the fibers without a collapse of their shape at mild temperature. This is accomplished via the DA reaction to prevent shearing between microfibrils when physical stress is applied to the film. The porous film is mechanically robust and reacts stably when the film is deformed or pressed. Electrodes are formed on both surfaces of the film using Ag nanowires (AgNWs). Vapor‐assisted partial melting of retro‐DA adducts is used to promote fusion of the polymer through the surface of the AgNWs and implement a robust stretchable electrode. The capacitance changes exceptionally uniformly with the magnitude of the applied pressure and deformation. Using this sensor, its functionality is successfully demonstrated by implementing a pressure sensor array composed of 9 px and measuring the external force applied to the balloon injected with air.