Intelligent Wearable Graphene Nano‐Electronics with Switchable Surface Wettability Capabilities for Autonomous Sweat Enrichment‐Purification‐Analysis

Abstract Sweat wearable biosensors facilitate continuous monitoring of individuals’ in‐depth body physiological state with real‐time and molecular‐level insight. However, limited detection accuracy and sensitivity resulted from insufficient amount of sweat sampling and impurities interferences still hinder their practical applications. Here, a miniature wearable skin‐interfaced intelligent graphene nano‐electronic (SIGN) patch employing a novel Janus membrane integrated surface wettability switchable microfluidic module with autonomous sweat sampling and purification capabilities is presented for in situ analysis of sweat biomarkers. Due to the asymmetric surface energy distribution characteristics of the microfluidic surfaces, rapid, directional transport of sufficient amount of sweat to the Janus membrane is achieved. The Janus membrane purifies the sweat sample and transport the sample to the sensing surface autonomously, thus eliminating impurities interferences and enhancing the sensing performance. An ultra‐flexible bio‐receptor functionalized graphene transistor for accurately monitoring sweat biomarkers such as lactate, with outstanding signal reproducibility and good long‐term (over 1 month) stability, and a signal processing unit are employed incorporating with the microfluidic module. In practical wearing tests, the SIGN patch enables the continuous measuring of sweat lactate levels for volunteers during exercises and intelligently providing a preliminary diagnostic assessment on their exercise intensity successfully, suggesting its potential commercialization prospects.