Disposable blood potassium sensors based on screen-printed thick film electrodes

A sensor based on the screen-printing technique for the rapid blood potassium test was developed. The sensor consists of a thick film potassium ion-selective electrode and a reference electrode. Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) was screen-printed on carbon electrodes as an internal solid contact layer for both ion-selective and reference electrodes. PVC membranes with and without selective ionphore valinomycin were coated on the PEDOT/PSS layer to form potassium ion-selective and reference electrodes, respectively. The potentiometric response characters were evaluated. The response time of the sensor was 15 s when less than 15 mu L of sample was applied. The sensitivity of the potassium sensor was around 60 mV per decade, while the potentiometric log selectivity coefficients were -3.43 and -3.48 for Na+ and Ca2+, respectively.