Surface Functionalized Ti3CNTx MXene for Monitoring Sweat pH with Superhydrophobic Protection

Abstract Real‐time tracking of metabolites, ions, and biomarkers in sweat using wearable sensors is crucial for advancing point‐of‐care testing, where improving the stability of these technologies is a major focus. In this research, a compact, highly sensitive, and stable real‐time electrochemical sweat sensor capable of monitoring changes in hydrogen ion concentration is developed. By surface functionalizing Ti 3 CNT x and combining it with a polyaniline film, a small, flexible pH sensor is fabricated to track biochemical reactions by examining sweat pH during exercise and wound healing. The fluorinated alkyl silane‐modified surface significantly increases the contact angle, enhancing the sensor's performance. The assembled pH sensor demonstrates pH‐sensitivity of −42.91 (pH 11–1) and −40.15 mV pH−¹ (pH 1–11), comparable to transition metal oxide‐based sensors. Additionally, it shows good selectivity through continuous addition and separated solution methods. The modified Ti 3 CNT x exhibited excellent durability in different ionic solutions for over 30 days. The flexible, precise sensor, developed via scalable screen‐printing, can be applied in water quality monitoring, food preservation, product processing, biomarker monitoring, and human health.