Wearable sweat-based sensor for non-invasive glucose monitoring: Fast transfer and enhanced accuracy with CNT@NH2/Cu-Ni carbon fiber patches
Milad Yousefizad, Negin Manavizadeh, Farshid Raissi
Abstract
• The study focuses on developing a non-invasive glucose monitoring system using a sweat-based electrochemical sensor with CNT@NH₂/Cu-Ni composite for improved accuracy and sensitivity. • The sensor, integrated into a wearable carbon fiber patch, overcomes challenges like sweat flow instability and delays in glucose detection. • Filter paper combined with carbon fibers stabilizes sweat volume on the sensor surface, reducing errors caused by excess electrolyte. • Incorporation of a pH sensor allows compensation for pH-induced errors caused by interfering substances like lactic acid, improving glucose measurement reliability. • The wearable sensor integrates wireless technologies (LoRaWAN, BLE, and Wi-Fi) for real-time data transmission, making it suitable for continuous, remote health monitoring. This study aims to improve non-invasive glucose monitoring using sweat-based electrochemical sensors. Challenges include delays in detecting glucose fluctuations and unstable sweat flow, which reduce accuracy. These issues are caused by variable sweat volume and potential sensor blockages or leaks. Efforts focus on optimizing materials for skin patches and sensor channel designs to enhance sweat transfer and minimize errors. The proposed system consists of a skin patch made from carbon fibers and Whatman paper to efficiently collect and transfer sweat to the sensor, along with an electrochemical sensor based on a CNT@NH₂/Cu-Ni/Nafion composite. Incorporating Nafion into the synthesized composite reduces the double-layer capacitance and eliminates non-Faradaic currents from the sensor output, thereby decreasing sensor noise. To evaluate the sensor's performance, its electrocatalytic activity was examined in an artificial sweat solution under different scan rates and glucose concentrations. The results indicated that the sensor exhibited a detection limit of 5 µM and a linear detection range of 20-500 µM, with a correlation coefficient of 0.998 and a sensitivity of 63.7 µA mM −1 cm −2 . Additionally, due to its low cost, adaptability, and mechanical flexibility, this system can facilitate and advance the development of wearable microfluidic devices for personal health monitoring and non-invasive, continuous glucose tracking. Consequently, the proposed system may serve as an effective tool for precise and optimal diabetes management, contributing to an improved quality of life for individuals with diabetes.