A novel wrinkle-gradient strain sensor with anti-water interference and high sensing performance

Abstract The application of strain sensors in extreme environments (such as moisture or rain droplets) is limited by the influence of water molecules on their sensing performance. Endowing strain sensors with superhydrophobicity is a promising strategy to solve this problem. However, it remains a challenge for superhydrophobic strain sensors to completely avoid the effects of water droplets. Herein, we developed a superhydrophobic strain sensor with gradient structure for the first time by a simple one-step pre-stretching method. The strain sensor exhibits high sensitivity (maximum gauge factor of 1199.10), a broad strain range (up to 400%), robust stability (3000 cycles), a low detection limit (0.1% strain), and fast response (88 ms), which can be used to monitor full-range human body motions. Furthermore, the gradient wrinkle structure with low surface energy makes the strain sensor have gradient superhydrophobic performance, so that the impacting water droplets can automatically deviate and bounce off the surface by the Young's force, avoiding the interference of water droplets on the sensor's electrical signal. Even when the strain is up to 400%, the impacting droplet can still offset and rebound, which makes the superhydrophobic strain sensor have stable sensing performance in extreme environments.