Enhancing the performance of hydrogel strain/pressure sensors via gradient-entanglement-induced surface wrinkling patterns.

This work proposes a facile strategy of constructing gradient entanglement dual network (GEDN) hydrogel with high surface area and greatly improved mechanical/sensing performance. The prepared hydrogel strain/pressure sensors show great potential in body movement detection and character recognition. [Display omitted] Due to the advantages of high mechanical compliance and good biocompatibility, conductive hydrogels exhibit great application potential in flexible electronics. As the requirements in high sensitivity and high mechanical performance are increasing, the construction of patterned surfaces has been proven an effective approach, yet most of the common methods are complex and high-cost. Herein, we proposed a facile strategy to construct gradient entanglement dual network (GEDN) hydrogel with spontaneously patterned surface and consequent high surface area, which greatly enhances the sensitivity of hydrogel sensors. The strategy of high entanglement as well as the dual network in hydrogel achieved greatly improved mechanical performance. The prepared polyvinyl alcohol (PVA)/gradient entangled polyacrylamide (PAAm) DN and surface-patterned hydrogel possesses the advantages of excellent stretchability (681 %), high tensile strength (1.01 MPa), toughness (4.23 MJ/m3), and relatively low mechanical hysteresis. Meanwhile, it showed high sensitivity, wide detection range, and rapid response both as strain sensor (GF max = 10.96, detection range = 681 %, an average response time of 170 ms) and pressure sensor (S max = 0.17 kPa−1, detection range = 225 kPa, an average response time of 230 ms). In summary, it provides a new strategy for design of the multifunctional high-performance flexible devices, exhibiting great application prospects. [ABSTRACT FROM AUTHOR]