Control of silver nanowire-elastomer nanocomposite networks through elaborate direct printing for ultrathin and stretchable strain sensors

Control of film's properties is the most important for providing of customized electronic devices. In particular, when the nanocomposite networks are applied to the films for needs of various applications, the quality of film is considered as one of the most potent factors. Here, we propose a viable and facile method of controlling the silver nanowire (Ag NW)-elastomer nanocomposite networks through elaborate direct printing for implementing sandwich-structured ultrathin and stretchable strain sensors. According to the different Ag NW network densities controlled by various blade coating parameters, surface morphological characteristics, optical transmittance, and current–voltage performance were investigated. In order to exhibit the importance of network density control to electronic devices, we fabricated two stretchable strain sensors with different sensitivities (ΔR/R₀: 6.31, 0.70 at 10% strain) using low density (LD) and high density (HD) Ag NWs networks for detecting small and large movements, respectively. Under repeated stretching fatigue tests (1000 cycles), LD and HD Ag NW sensors show stable sensing operation with electromechanical durability and frequency-responsive features. A simple application for wrist motion detection with a fast response speed and stable operation is demonstrated. These results provide a new route towards next-generation skin electronics.