Hydroxyethyl cellulose-based stretchable, antifreeze, ion-conductive hydrogel sensor

Ion-conducting hydrogels are a widely recognised material for skin sensors and significant progress has been made in the development of stretchable and self-healing conductive materials. However, hydrogels still present challenges in terms of water retention and frost resistance, which have a profound impact on their mechanical and conductive properties. In order to address these issues, we have used a straightforward approach to fabricate novel ion-conductive hydrogels. In this study, physical interactions and covalent binding in the hydrogel-based system conferred excellent tensile properties (up to 1071.3 % strain) and high toughness (927 kJ/m 3 ), in addition to the introduction of hydroxyethyl cellulose that enabled the hydrogels to have good biocompatibility and mechanical properties, and the strong hydration of lithium chloride that conferred the hydrogels high electrical conductivity (2.16 S/m) and frost resistance. In particular, the hydrogel containing 5 wt% lithium chloride showed significant flexibility and extensibility even under the harsh conditions of −15℃, indicating its potential for cold climate applications.