Surface-tension-directed gate functionalization in organic electrochemical transistor for wearable sweat lactate monitoring

Wearable sweat lactate detection holds significant potential for applications in healthcare and exercise performance evaluation. Organic electrochemical transistors (OECTs) is emerging as an efficient platform in wearable lactate sensing by integrating an electron transfer interface between the electrode and the bio-catalytic layer. In this study, we demonstrated a wearable OECT designed for dynamic lactate monitoring in sweat through a one-step deposition of gold nanoparticles (Au NPs) on the gate electrode. Utilizing the simple surface-tension-directed deposition strategy, this method ensures a uniform distribution of Au NPs with high catalytic activity, enabling rapid and sensitive lactate signal transition. Herein, the OECT device exhibits a linear detection range for sweat lactate from tens of micromolars to hundreds of millimolars (r² > 0.97), along with high selectivity and long-term stability in human sweat. Furthermore, we successfully employed this flexible OECT sensor for real-time lactate monitoring system during various physical activities, highlighting its potential for non-invasive evaluation of fatigue and exercise performance in athletes. This work provides an easy-to-use prototype for continuous physiological monitoring, enhancing personalized healthcare and training management. • In this study, we proposed a surface-tension-directed method for the uniform deposition of gold nanoparticles (Au NPs) by simply processing the electrodes surface tension. This strategy facilitated the formation of an electron transfer layer with high catalytic activity, enabling rapid and sensitive lactate signal transduction in an organic electrochemical transistor (OECT). • Based on the Au NP-functionalized OECT, we developed a flexible lactate sensor with operating voltage of V DS = −0.03 V and V GS = 0.2 V. The device exhibits a linear detection range for sweat lactate, from tens of micromolars to hundreds of millimolars, with high selectivity and long-term stability. • Utilizing this flexible OECT, a wearable sweat sensor patch was prepared for real-time monitoring of lactate levels in sweat during exercise, providing a convenient tool for assessing fitness and health.