Janus hydrogel combines anti-freezing and adhesive properties for sweat glucose monitoring

Wearable electrochemical sensors have gained increasing attention for non-invasive, real-time monitoring of sweat biomarkers, particularly for applications such as diabetes management. However, the integration of high sensitivity, strong adhesion, and anti-freezing capabilities into a single flexible sensing platform remains a significant challenge. To address this, we present a Janus hydrogel-based wearable glucose sensor that integrates asymmetric material design for multifunctional performance. The hydrogel patch consists of a carboxymethyl cellulose/polyvinyl alcohol (CMC/PVA) matrix with two functionally distinct layers formed by the addition of different substances. The outer layer is modified with glycerol (GLY), which imparts excellent anti-freezing properties, maintaining flexibility under low-temperature conditions. Polydopamine (PDA) was added to the inner hydrogel to enhance adhesion, and glucose oxidase-modified polyethyleneimine-coated gold nanorods (GOD@PEI@AuNRs) were added to improve the detection ability of the glucose sensor. This Janus hydrogel has an antifreeze temperature of -38 °C and a wide detection range (10-350 μM) with a detection limit as low as 0.21 μM.