This paper reports on the development of a fexible-wearable potentiometric sensor for real-time monitoring of sodium ion (Na+ ), potassium ion (K+ ), and pH in human sweat. Na0.44MnO2, polyaniline, and K2Co[Fe(CN)6] were used as sensing materials for Na+ , H+ and K+ monitoring, respectively. The simultaneous potentiometric Na+ , K+ , and pH sensing were carried out by the developed sensor, which enables signal collection and transmission in real-time to the smartphone via a Wi-Fi access point. Then, the potentiometric responses were evaluated by a designed android application. Na+ , K+ , and pH sensors illustrated high sensitivity (59.7 ± 0.8 mV/decade for Na+ , 57.8 ± 0.9 mV/decade for K+ , and 54.7 ± 0.6 mV/pH for pH), excellent stability, and good batch-to-batch reproducibility. The results of on-body experiments demonstrated that the proposed platform is capable of real-time monitoring of the investigated ions.
