Recent advances of wearable electrochemical and optical sensors for sweat pH monitoring.

Measuring the pH of human biofluids provides meaningful information about physiological balance and potential pathological changes. While blood remains the conventional medium for diagnostic evaluation, there has been an increasing focus on external biofluids, such as sweat, that enable non-invasive, continuous health assessment. Recent advances in wearable sensing technologies have resulted in the development of flexible, miniaturized and biocompatible systems that can monitor sweat pH in real time on the body. This review highlights the latest progress in wearable electrochemical and optical sensors designed for sweat pH monitoring. It first outlines the general procedures for sweat pH sensing, including sweat secretion and collection, pH sensing, signal conversion, and data interpretation. Subsequent sections focus on electrochemical approaches, particularly potentiometric sensors based on ion-selective membranes and ion-sensitive field-effect transistor (ISFET) configurations, which are recognized for their high sensitivity and rapid response times. The review further explores optical sensing technologies, such as surface-enhanced Raman scattering (SERS), fluorescence and colorimetric sensors, emphasizing their versatility for visual and spectroscopic detection. Looking ahead, the integration of artificial intelligence, microfluidic systems, and self-powered modules will facilitate the development of fully autonomous, wireless sensing platforms. The convergence of advanced materials, sensor engineering, and digital health technologies is expected to establish wearable sweat pH sensors as a cornerstone of personalized medicine, preventive care, and real-time health tracking.