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.