Wearable and wireless monitoring of biomarkers such as lactate in sweat can provide a deeper understanding of a subject’s metabolic stressors, cardiovascular health, and physiological response to exercise. However, the state-of-the-art wearable and wireless electrochemical systems rely on active sweat released either via high-exertion exercise, electrical stimulation (such as iontophoresis requiring electrical power), or chemical stimulation (such as by delivering pilocarpine or carbachol inside skin), to extract sweat under low-perspiring conditions such as at rest. Here, we present a continuous sweat lactate monitoring platform combining a hydrogel for osmotic sweat extraction, with a paper microfluidic channel for facilitating sweat transport and management, a screen-printed electrochemical lactate sensor, and a custom-built wireless wearable potentiostat system. Osmosis enables zero-electrical power sweat extraction at rest, while continuous evaporation at the end of a paper channel allows long-term sensing from fresh sweat. The positioning of the lactate sensors provides near-instantaneous sensing at low sweat volume, and the custom-designed potentiostat supports continuous monitoring with ultra-low power consumption. For a proof of concept, the prototype system was evaluated for continuous measurement of sweat lactate across a range of physiological activities with changing lactate concentrations and sweat rates: for 2 h at the resting state, 1 h during medium-intensity exercise, and 30 min during high-intensity exercise. Overall, this wearable system holds the potential of providing comprehensive and long-term continuous analysis of sweat lactate trends in the human body during rest and under exercising conditions.

中文翻译：

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用于连续乳酸监测的零功率渗透排汗无线可穿戴电化学传感平台

可穿戴和无线监测诸如汗液中的乳酸等生物标志物，可以更深入地了解受试者的代谢压力源、心血管健康和对运动的生理反应。然而，最先进的可穿戴和无线电化学系统依赖于通过以下方式释放的主动汗液高强度运动、电刺激（例如需要电力的离子电渗疗法）或化学刺激（例如通过在皮肤内输送毛果芸香碱或卡巴胆碱），以在低出汗条件下（例如在休息时）提取汗液。在这里，我们提出了一个连续的汗液乳酸监测平台，该平台结合了用于渗透汗液提取的水凝胶、用于促进汗液运输和管理的纸质微流体通道、丝网印刷的电化学乳酸传感器和定制的无线可穿戴恒电位仪系统。渗透能够在静止时实现零电力汗液提取，而纸通道末端的连续蒸发允许从新鲜汗液中进行长期感应。乳酸传感器的定位在低汗液量下提供近乎瞬时的传感，定制设计的恒电位仪支持超低功耗的连续监测。为了验证概念，该原型系统被评估为在一系列生理活动中连续测量汗液乳酸，乳酸浓度和出汗率发生变化：静息状态下 2 小时，中等强度运动期间 1 小时，以及 30 分钟在高强度运动时。总体而言，这种可穿戴系统具有对休息和运动条件下人体汗液乳酸趋势进行全面和长期连续分析的潜力。对原型系统进行了评估，以在一系列生理活动中随着乳酸浓度和出汗率的变化连续测量汗液乳酸：在静息状态下测量 2 小时，在中等强度运动期间测量 1 小时，在高强度运动期间测量 30 分钟。总体而言，这种可穿戴系统具有对休息和运动条件下人体汗液乳酸趋势进行全面和长期连续分析的潜力。对原型系统进行了评估，以在一系列生理活动中随着乳酸浓度和出汗率的变化连续测量汗液乳酸：在静息状态下测量 2 小时，在中等强度运动期间测量 1 小时，在高强度运动期间测量 30 分钟。总体而言，这种可穿戴系统具有对休息和运动条件下人体汗液乳酸趋势进行全面和长期连续分析的潜力。