Fingertip Sweat Leucine Detection Based on Electrochemical MIP Sensors Integrated with Porous Hydrogels

Leucine (Leu) is a promising biomarker for metabolic health and muscle growth, offering significant potential for assessing physical well-being. Sweat sensors for Leu detection eliminate the reliance on invasive blood analysis and the sophisticated, large-scale instrumentation. Current sweat sensors, however, are complex to fabricate, exhibit low sensitivity toward nonelectroactive Leu, require intense exercise or thermal/chemical stimulation to generate sweat, and lack reusability. This work reports a flexible, highly sensitive, and reusable sweat sensor based on molecularly imprinted polymers, Prussian blue nanoparticles, and laser-induced graphene. When integrated with a highly permeable porous Poly(vinyl alcohol) hydrogel for convenient and rapid collection of instantaneous sweat secreted from the fingertip, the sensor can continuously detect Leu with high sensitivity (7641 nA mm–2 per decade), low detection limit (10 nM), and excellent repeatability. This flexible biosensing patch offers a promising strategy for noninvasive sweat Leu analysis and wearable health monitoring, showing potential for assessing health status related to obesity, type 2 diabetes (T2DM), and muscle loss.