Anti-freezing, adhesive and conductive hydrogel for flexible sensors and deep learning assisted Triboelectric nanogenerators

The development of the flexible sensors has attracted a lot of researchers’ interests. Conductive hydrogel has been regarded as an ideal candidate in flexible sensors due to its stretchability and superior flexibility, which minimized the possibility of damage during operation. However, due to the fact that the main component of hydrogels is water, they tend to freeze under low-temperature conditions, which limits their range of applications. In this work, an anti-freezing gelatin/PAM/LiCl hydrogel with excellent conductivity was fabricated, after optimization, the hydrogel possessed a conductivity of 1.01 S·m −1 , and excellent mechanical properties (tensile stress of 0.15 MPa, tensile strain of 618.03 %). With the excellent properties, hydrogel-based strain sensor and pressure sensors were fabricated, showing its huge potential to be applied in flexible devices. In addition, hydrogel-based triboelectric nanogenerator was also prepared with excellent output characteristics and long-term stability. Triboelectric nanogenerator was used to capture signals generated by different motions. Combined with deep learning algorithm, a high accuracy of 97.62 % was achieved for motion classification task. This work developed a new strategy for building flexible electronics operating at low temperature.