Anion-sensitive field-effect transistors based on sol-gel-derived membranes incorporating quaternary ammonium salts

Quaternary alkylammonium chlorides were encapsulated or bonded covalently t o sol-gel-derived membranes made of mixtures of two alkoxysilanes so as to obtain sensing membranes for anion-sensitive field-effect transistors. Both types of anion sensors responded to chloride-ion activity changes with hig h sensitivity. The anion-sensing membranes modified chemically by an alkoxy silyl derivative of quatenary ammonium salt are superior to those simply en capsulating an ammonium salt in their durability and protein-adsorption pro perties. The anion sensors are applicable to chloride-ion assay in serum sa mples.