Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States.
Department of Electrical & Computer Engineering, North Carolina State University, 890 Oval Drive, Raleigh, North Carolina 27695, United States.
ACS Sens. 2022 Jul 22;7(7):2037-2048. doi: 10.1021/acssensors.2c00830. Epub 2022 Jul 12.
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 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.
可穿戴式和无线监测生物标志物，如汗液中的乳酸，可以更深入地了解受试者的代谢应激、心血管健康和对运动的生理反应。然而，最先进的可穿戴式和无线电化学系统依赖于主动释放汗液，要么通过高强度运动、电刺激（如需要电力的离子电渗法），要么通过化学刺激（如在皮肤内递送毛果芸香碱或卡巴胆碱），以在低出汗条件下提取汗液，例如在休息时。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，用于促进汗液传输和管理的纸质微流控通道，用于电化学乳酸传感器的丝网印刷，以及定制的无线可穿戴式电化学工作站系统。渗透作用使零电力的汗液在休息时得以提取，而纸质通道末端的连续蒸发允许从新鲜汗液中进行长期感测。乳酸传感器的定位提供了低汗液量的即时感测，而定制的电化学工作站支持超低功耗的连续监测。为了验证概念，该原型系统在一系列生理活动中对汗液乳酸进行了连续测量，包括不同乳酸浓度和汗液率的 2 小时休息状态、1 小时中等强度运动和 30 分钟高强度运动。总的来说，这个可穿戴系统有可能在休息和运动条件下对人体汗液乳酸趋势进行全面和长期的连续分析。
