Enhanced high-strength, temperature-resistant PVA hydrogel sensors with silica/xanthan/glycerol for posture monitoring and handwriting recognition using deep learning

Abstract

Ion-conducting hydrogels are gaining significant attention for use in flexible electronics such as sensors and e-skins due to their exceptional skin compatibility and excellent mechanical and sensing properties. However, their unsatisfactory electrical and mechanical performance under extreme temperatures poses a challenge to practical applications. To overcome this limitation, this study presents polyvinyl alcohol/lithium ions/xanthan gum/silica nanoparticles/glycerol ion-conducting hydrogels (PLXSG) that exhibit stable operation between −40 °C and 70 °C. The hydrogel is reinforced by a polyvinyl alcohol (PVA) network integrated with glycerol, while a secondary network of xanthan gum (XG) and silica nanoparticles further enhances strength and durability. These hydrogels dissipate energy through sacrificial bonding, with lithium ions in water–glycerol solvents significantly enhancing ionic conductivity and freeze resistance. Experimental results demonstrate that PLXSG hydrogels possess remarkable tensile properties, achieving a maximum elongation of 790% and a tensile strength of 1.8 MPa. Moreover, they display high sensitivity, with a gauge factor (GF) of 3.623 at strains exceeding 175%, high ionic conductivity (0.767 S cm⁻¹), rapid recovery at 100% strain, and a low strain detection limit (0.3%). The material maintains both electrical and mechanical stability across the temperature range of −40 °C to 70 °C. These attributes, combined with environmental resilience, underscore the hydrogel's potential for advanced flexible electronic applications.