Non-Invasive and Continuous Monitoring of Lactate in Interstitial Fluid for Real-Time Metabolic Assessment

Lactate is a key biomarker for metabolic assessment, but existing detection methods are either invasive or noninvasive with limited accuracy. This work presents a noninvasive, wearable device for continuous interstitial fluid (ISF) lactate monitoring, which consists of curved reverse iontophoresis (RI) electrodes and a three-electrode lactate enzymatic sensor incorporating lactate oxidase (LOx), platinum nanoparticles (PtNPs) and Prussian blue (PB). A polarity-switching RI method is adopted to restrain electrode degradation and ensure stable ISF extraction. The device exhibits high sensitivity, strong selectivity against common interferents and excellent reproducibility. Extracted lactate concentrations show linear correlation with subcutaneous ISF levels, thereby enabling accurate prediction. These findings establish a solid foundation for reliable non-invasive continuous lactate monitoring, providing new insights for real-time metabolic assessment.