Non-invasive and wearable glucose biosensor based on gel electrolyte for detection of human sweat

Flexible, wearable biosensors have been extensively investigated in recent decades due to their potential applications in portable electronics and human health monitoring. However, low sensitivity and complex fabrication are still great challenges for flexible sensors. Herein, a flexible electrochemical biosensor for glucose was proposed, which was based on reduced graphene oxide and gold nanoparticle-modified screen-printed gold electrodes (rGO-Au/SPGE) as catalysts and gel instead of traditional liquid electrolyte. The biosensor combines the soft stretchability of the gel, the specific selectivity of glucose oxidase (GOx) and the high catalytic activity of the rGO-Au/SPGE nanocomposite. More importantly, the soft gel not only adheres well to the skin, but also promotes the penetration of water-soluble molecules, effectively improving the accumulation of bodily fluids on dry skin surfaces. The constructed GOx-gel-rGO-Au/SPGE biosensor maintains stable sensing performance even after 1000 bending cycles. In addition, the biosensor exhibited significantly current response to glucose at a detection range of 1.25-850 mu M and 0.85-7.72 mM (covers the glucose level in human sweat), with a sensitivity of 53.7 and 27.4 mu A/mM cm(2) and low detection limit (1.25 mu M). The flexible electrochemical biosensor based on GOx-gel-rGO-Au/SPGE could accurately determine glucose in human sweat, demonstrating a promising feature for personal healthcare diagnosis.