Wearable sweat sensor system with dynamically adjustable sensitivity for simultaneous detection of multiple...

Wearable sweat sensor systems, which monitor target biomarkers in sweat, play a crucial role in sports and health monitoring. However, there are two major challenges: first, the difficulty of simultaneously monitoring multiple biomarkers; and second, the inability to dynamically adjust sensitivity, which limits their detection range. To address the complexity of sweat composition and the wide variation in concentration ranges, we propose an adaptive amplification circuit for extremely weak current signals, combined with a time-division detection strategy tailored for sweat sensor systems. This system enables dynamic adjustment of current sensitivity and simultaneous detection of multiple biomarkers in sweat, such as glucose, lactate, Na⁺, and K⁺. We utilize an integrated, numerically controlled, switchable feedback resistor network transimpedance amplifier (TIA) circuit architecture to achieve dynamic adjustment of current sensitivity over a broad range from 10 nA to 2 mA and to enhance the linear correlation coefficients for glucose and lactate detection, reaching 0.998 and 0.995, respectively. To further realize multi-channel synchronous acquisition, the system employs a numerically controlled switch circuit combined with a time-division multiplexing strategy and dual TIA channels to simultaneously monitor 4 types of sweat biomarkers. During in vivo cycling experiments, the sensor system successfully demonstrated in vivo monitoring of 4 biomarkers in human sweat. This study provides an effective technical solution for multi-biomarker detection and health monitoring with a wide detection range.