Wearable Iridium Oxide pH Sensors for Sweat pH Measurements

Abstract

A sensor on ultra-flexible substrate has been developed for skin pH measurements to monitor antimicrobial effects, skin aging and potential disease status. The sensor consists of an iridium oxide working electrode and a silver chloride reference electrode. The sensor is characterized with varying pH values in artificial sweat as control. The sensor is also tested within a cotton pad packaging for wearables and directly on skin, in considerations of hydrostatic effects on the electrochemical sensors. The sensor presents distinguishable outputs in artificial sweat, containing multiple interference ions, and good sensitivity with little hysteresis within the pH range of 5 to 8. The sensor can be used in a bandage-like packaging on skin with calibration since its sensitivity is reduced by the cotton fiber pad due to limits of ion exchanges in hydrostatic conditions.