Ion selective textile organic electrochemical transistor for wearable sweat monitoring

Textile organic electrochemical transistors (txOECTs) are a new class of wearable biosensors used to monitor physiological parameters in bio fluids of clinical interest. Herein the selectivity of a textile biosensor was improved directly functionalizing the textile device with ion selective membranes. The device was prepared by a series of consecutive functionalization of the textile fiber, first by applying the conductive polymer poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) and subsequently the ion selective membrane based on different ionophores with the aim of measuring electrolytes in sweat. The ion selective membranes were previously tested and optimized by potentiometric measurements. The biosensor devices were studied with different concentration of electrolytes. Membrane selectivity was tested comparing transistor response with interfering ions, proving successfully the selective response to sodium, potassium and calcium ions. The ability of the textile biosensors to discriminate among the cations was demonstrated over the 10-5 - 1 M concentration range, a concentration range found in sweat. The electronic parameters of the txOECTs show differences not only in modulation response but also in time constants of kinetic behavior. The selective determination of potassium and calcium in sweat has a great importance in different applications, for example, in human sweat monitoring, to understand physiological conditions, like dehydration, cardiac bioactivity and hypokalemia.