A flexible and high sensitivity pH sensor based on poly(3,4-ethylenedioxythiophene): indigo carmine for human sweat monitoring

Human sweat pH closely correlates with physiological states, making its monitoring vital for health maintenance and personalized medicine. A flexible electrochemical sweat pH sensor was fabricated using a poly(3,4-ethylenedioxythiophene):indigo carmine/screen-printed carbon electrode (PEDOT:IC/SPCE). The sensing performance of pH sensor is optimized by adjusting the structure of functional coating through voltage design in electropolymerization process. The results show that the pH sensor prepared under 1.0 V constant voltage polymerization has the best performance. The sensor has a wide detection range (pH 2–11), high sensitivity (65 mV/pH) and good accuracy (deviation ≤ ±0.25 pH vs. commercial pH meter). Comprehensive stability tests were conducted, including repeatability, continuous operation, anti-interference ion resistance, storage stability, and mechanical bending tests. This work demonstrates the potential of wearable electrochemical sensors for health management applications.