FET-based sensors with robust photosensitive polymer membranes for detection of ammonium ions and urea

Abstract

The properties of a potentiometric field effect transistor (FET)-based sensor with a robust polymer photo- and ion-sensitive membrane were studied. The membrane was fabricated from polyethylene terephthalate (PETPh) film modified by spiropyran (SP) and nonactin (NA) using the crazing method. This method makes it possible to impregnate local polymer defects with low molecular weight substances. The presence of spiropyran in the membrane upon the UV-irradiation provides the generation of membrane photopotential, whose value in the presence of NA becomes a function of NH 4 + concentration in the solution. The sensor was shown to have the optimal working range 10 −6–10 −4 M for NH 4 + (pH 5·0 1mM LiH 2PO 4) and 10 −5–10 −3 M (pH 6.4, 10 mM LiH 2PO 4) for urea with immobilized urease as a catalyst.