Highly Reproducible Flexible Ion‐selective Electrodes for the Detection of Sodium and Potassium in Artificial Sweat

Abstract It is well known that potentiometric sensors provide a versatile, cost‐effective, and efficient platform for wearable applications. Unfortunately, mass production and commercialization of such devices is often constrained by the requirement of a calibration step, which is due to the poor sensor‐to‐sensor reproducibility and the need of conditioning the electrodes in the analyte before use. Herein, we fabricated calibration‐free flexible sensors including ion‐selective electrode and reference electrode by integrating single‐walled carbon nanotubes (SWCNTs) with poly(3‐octylthiophene) (POT) and applying on polyethylene terephthalate (PET) substrate. The developed sodium and potassium ion‐selective electrodes (ISEs) display excellent repeatability, selectivity, stability as well as high sensor‐to‐sensor reproducibility, with a standard deviation of as low as 1.0 mV in artificial sweat microliter samples volume.