A wearable paper-based SGR/MCC microneedle array sensor for continuous glucose monitoring

Continuous glucose monitoring (CGM) is a promising approach for managing blood glucose levels in individuals with diabetes. However, the emerging microneedle (MN) technologies for colorimetric or electrochemical detection of glucose in sampled dermal interstitial fluid (ISF) remain far from practical CGM due to many concerns. Herein, we propose a new disposable solid MN array on a flexible paper substrate, integrated with reusable electronics and a mobile application, for electrochemical glucose sensing in ISF. The paper substrate was prepared by infusing paper with UV-cured flexible gingiva mask resin, ensuring body comfort. The solid MN array was fabricated from a newly developed composite of UV-cured biocompatible surgical guide resin (SGR) and microcrystalline cellulose (MCC), using a simple self-developed fabrication technique, ensuring safe skin interaction. The paper-based composite MN arrays were converted into conductive biosensing electrodes by coating them with graphene ink and additional functional modifiers via airbrushing, and subsequently integrated into a wearable patch for continuous ISF glucose monitoring. The resulting MN array electrodes exhibited excellent analytical performance in monitoring glucose of ex vivo porcine plasma, hydrogel-based artificial skin, and in vivo mice, with high sensitivity, selectivity against interferents, and robust stability. This study provides a simple, cost-effective, and eco-friendly path for the development of wearable electroanalytical devices toward practical CGM.