Effect of membrane structure on the performance of field-effect transistor potassium-sensitive sensor

Abstract

An EET-type K+ -sensitive sensor with a membrane composed of a hydrophobic inner layer and a hydrophilic outer layer has been fabricated by a photolithographic process. The base chip for the sensor is a pH-ISFET with a thin Si3N4 layer. Negative photoresist (OMR-83) is used as the inner layer and poly(vinyl pyrrolidinone-co-vinyl acetate) solution in tetrahydrofuran containing valinomycin and 2,6-bis-(p-azidobenzylidene) cyclohexanone photosensitizer is used as the outer sensing membrane material. The K-ISFET sensor with double-layered membrane shows a high sensitivity (56 mV/decade) toward K+ ion, rapid response (1-2s) and low interference (less than 3mV/decade) from the competing H+ ion