Janus Membrane-Based Wearable Dual-Channel SERS Sensor for Sweat Collection and Monitoring of Lactic Acid and pH Levels

Sweat, as a metabolic byproduct, encompasses a diverse array of molecular information pertinent to our physiological states and overall health. The extraction of minute quantities of sweat, coupled with sensitive monitoring and identification of its internal molecular components, constitutes an effective strategy for assessing bodily conditions. We engineer a Janus membrane utilizing electrospinning techniques for application on human skin to facilitate sweat collection. The hydrophilic layer efficiently extracts trace amounts of sweat secreted by the skin, while the hydrophobic layer maintains a dry contact interface, thereby enhancing the user's comfort during wear. Furthermore, we integrated functional self-assembled nanoparticle layers onto the hydrophilic surface to develop a dual-channel high-sensitivity sensor array capable of measuring pH and lactic acid concentrations. This system adeptly distinguishes between anaerobic exercise and calm state scenarios concerning pH and lactic acid levels.