Stretchable and high sensitive ionic conductive hydrogel for the direction recognizable motion detection sensor

Due to the good conductivity and adjustable mechanical properties, ionic conductive hydrogel is considered an ideal candidate for use in wearable electronic devices. However, maintaining good flexibility, conductivity, and high sensitivity of electromechanical performance, though highly desirable, remains a great challenge. In this work, a zwitterionic ionic conductive hydrogel (CMHZ: chitosan/polyacrylic acid-acrylamide/ZnSO₄) was prepared with excellent mechanical properties, ionic conductivity, and high sensitivity. The CMHZ showed excellent adjusted mechanical properties (up to 1210% tensile strain under 0.15 MPa, toughness 5.42 MJ/m³) and good shape-recovery ability. Meanwhile, the free-moving metal ions in the hydrogel guaranteed the CMHZ with good conductivity (33.73 mS/cm). More importantly, the unique zwitterionic structure made the hydrogel have a wide working voltage range (0 - 2.0 V), which endowed the hydrogel with a significant improvement of sensitivity up to GF = 4.22. Based on these obvious advantages, the CMHZ hydrogel was used as a stretchable sensor demonstrated high-sensitivity physiological signal detection and motion direction recognition, suggesting wide potential in flexible electronic devices.