Carbon-Nanotube Synergized Robust Enzymatic-Fuel-Cell in Gel Microneedle for Self-Powered Monitoring and Forecasting

Abstract

Implementation of an enzymatic biofuel cell-based wearable device for the self-powered monitoring of dynamic biomarkers in interstitial fluid is crucial for precision medicine. Such devices are mainly limited by unimpaired immobilization and electron transformation of enzymes on electrode. Here, a gel microneedles bioelectrode utilized is designed by interfacial enzymatic polymerization from the aligned carbon fibers for initiating rigid gel shell array on surface, ensuring intact encapsulation of three oxidases with efficient substrate osmosis. Carbon nanotubes are employed to bridge each carbon fiber with the oxidase, accelerating the electrons transfer from active center of enzyme to external circuit. This strategy, which achieves a maximum power density of 1.98 mW cm⁻² at 20 mm glucose as biofuel cell, with glucose detection limits as low as 0.2 mm. Similarly, the detection limits for lactic acid and uric acid can be as low as 0.2 and 0.05 mm. Validation in diabetic rats with the integration of data capture and an AI-assisted analyst system, enables precise detection of stimuli, such as food intake and exercise, allowing for the accurate prediction of biomarker dynamics in the next 20 min. This integrated system marks a significant stride toward the realization of truly personalized and responsive healthcare solutions.