A low-cost hydrogel with high conductivity and flexibility for pressure sensor and supercapacitor

The dramatic growth of wearable electronics is generating surge in demand for conductive hydrogels. The development of conductive hydrogels for sensing and energy storage via low-cost and simple design preparation is highly anticipated but challenging. In this work, polyvinyl alcohol/acrylic acid hydrogel (PVA/AA) is prepared by copolymerization method. The hydrogel's high electrical conductivity and impressive elasticity make it an attractive substrate for flexible pressure sensors and supercapacitors. The PVA/AA hydrogel-based pressure sensor delivers exceptional sensitivity (0.841 kPa−1), quick response (0.15 s), and wide pressure range (0–30 kPa). The outstanding properties imply its potential for detecting physiological signals and monitoring human movement. The flexible supercapacitor prepared with a PVA/AA hydrogel as electrolyte offers an areal specific capacitance of 345.7 mF cm−2 at a current density of 0.5 mA cm−2, with high cycling stability (82.8% capacity after 3,000 cycles). Additionally, serial devices can power a timer for more than 30 min.