Wearable Microfluidic Dual Screen-Printed Sensor for Simultaneous Monitoring of Sweat pH and Lactate

Abstract

Sweat lactate monitoring has recently garnered increasing attention for assessing athlete performance, optimizing training, and determining fatigue levels. Thus, this study introduces a wireless dual-biosensor device for continuous monitoring of sweat lactate and pH. The pH sensor exhibits a sensitivity of −61 ± 0.5 mV pH⁻¹, while the lactate sensor displays a sensitivity of 0.0149 ± 0.0004 mA cm⁻² mM⁻¹ at pH 7.5. We establish a method to precisely measure lactate within the pH range of 5.5 to 7.5, taking into account the pH-dependent sensor sensitivity. The dual-biosensor device incorporates polydimethylsiloxane microfluidics for collection of sweat, its delivery to the sensor, and disposal of used sweat, enabling continuous and precise monitoring. On-body tests demonstrate the ability of the proposed device to continuously monitor sweat pH and lactate levels in individuals during exercise.