Surface Functionalized Ti3CNTx MXene for Monitoring Sweat pH with Superhydrophobic Protection

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.