Transparent Electronic Skin from the Integration of Strain Sensors and Supercapacitors

Abstract Some of the major challenges for electronic skin (E‐skin) are to achieve accurate and continuous monitoring of human activities/health condition, eliminating wired external power sources. The ideal E‐skin should be ultra‐sensitive, self‐powered, conformal to human skin, and optically transparent for visual or aesthetic purposes. In this paper, a self‐powered all‐in‐one transparent E‐skin is constructed by integrating a flexible transparent supercapacitor (FTSC) as an energy storage device with a stretchable transparent strain sensor. The assembled FTSC uses oxygen‐deficient molybdenum oxide (MoO x ) nanowires and cellulose nanofiber composite as paper electrodes, achieving an excellent combination of high transparency and outstanding energy‐storage capacity (12.1 mF cm −2 ) to drive the operation of the sensor. Meanwhile, the synergistic effect of 1D nanowires bridging 2D nanosheets in the skeleton network provides the transparent strain sensor with ultra‐high sensitivity (high gauge factor up to 220 under 1% strain), high signal‐to‐noise ratio, fast response time (≈50 ms), and excellent stability. The E‐skin being conformally attached to various parts of the human body enables real‐time detection of subtle physiological signals and joint movements.