Wearable Sensor for Continuous Monitoring Multiple Biofluids: Improved Performances by Conductive Metal-Organic Framework with Dual-Redox Sites on Flexible Graphene Fiber Microelectrode

Abstract

Wearable sensors hold significant promise for continuous, real-time, and non-invasive analysis in biofluids. However, current wearable sensor technologies suffer from low accuracy for detecting trace analytes, inevitable signal distortion due to deformation, and inadequate biofluid replenishment. Herein, a wearable electrochemical sensor is developed by integrating designed metal-organic frameworks (MOFs) modified graphene fiber (GF) microelectrode into a flexible microfluidic chip. The proposed atomically precise phthalocyanine-based MOFs, with high-density dual-redox sites and intrinsic conductivity, ensure highly sensitive and selective electrochemical detection of the metabolite uric acid (UA) and tyrosine (Tyr) in biofluids. The freestanding, functionalized GF microelectrode is assembled from graphene nanosheets. Therefore, it exhibits excellent mechanical flexibility, a large surface area, and high temporal/spatial resolution. This contributes to a robust bio-interface adaptable to various skin areas and improves the accuracy for in vivo detection. Consequently, the high-performance electrochemical sensing system based on the GF microelectrode modified by dual-redox-sites MOFs, integrated with a microfluidic chip for efficient collection and rapid replenishment of raw biofluids, results in a practical wearable sensor for real-time monitoring of UA and Tyr in sweat and saliva, which are utilized for non-invasive gout management by tracking metabolite levels in gout patients and healthy controls during a purine-rich dietary challenge.