Detection of Micromolar Glucose Levels in Human Sweat Using an Organic Transistor-Based Enzymatic Sensor

Sweat glucose serves as a significant biomarker of health, necessitating accurate determination at the micromolar level for noninvasive monitoring. To address this need, we design an organic field-effect transistor (OFET)-based enzymatic sensor to quantify glucose levels in human sweat. The extended-gate structure of the OFET device ensures stable analyte detection in human sweat owing to its isolated configuration. The extended-gate-type OFET has been functionalized with glucose oxidase and an N-ethylphenazonium-based mediator-attached monolayer. This configuration facilitates electron relay, enabling accurate and reproducible glucose detection. Leveraging the amplification ability of the OFET, the enzymatic sensor exhibited highly sensitive glucose detection, achieving a low limit of detection (2.9 μM) suitable for sweat analysis requirements. In addition, the sensor exhibited high discriminability in detecting glucose amidst interferents commonly found in sweat, indicating its practical feasibility for sweat analysis. Validation of glucose recovery rates (95–105 %) in human sweat, without pretreatment, was performed using established instrumental analysis methods.