A High-Sensitivity Flexible Sweat pH Sensing Patch Based on a Screen-Printed PANI Sensing Layer

Sweat contains a rich repertoire of biomarkers that can reflect physiological health statuses, such as electrolyte imbalance, stress levels, and certain diseases. This makes it an ideal biofluid for continuous, noninvasive monitoring via miniaturized wearable electrochemical biosensors. Herein, we developed a wearable sweat pH-sensing patch. The patch incorporates a polyaniline (PANI)-based pH-sensing electrode fabricated via screen-printing technology, which features a high specific surface area, enabling the simultaneous and real-time monitoring of sweat pH. The as-fabricated pH sensing patch demonstrates a high sensitivity of 45.8 mV·pH−1, a good linear response (R2 = 0.9732), excellent cycling stability, a rapid response time (20 s), and a broad detection range (pH 3 ∼ 8). Furthermore, when integrated with a self-developed miniaturized acquisition system, the patch successfully captured the dynamic variations in sweat pH during human physical exercise, thereby validating its stability and reliability in real-world scenarios. This work provides an effective wearable solution for personalized health monitoring and scientific exercise assessment, showcasing considerable application potential.