Urea and Glucose Sensors Based on Ion Sensitive Field Effect Transistor with Photolithographically Patterned Enzyme Membrane

Abstract

A polyvinylpyrrolidone (PVP) based photocrosslinkable polymer has been used to make an enzyme membrane on an ion sensitive field effect transistor (FET). An enzyme and a lysine-rich polypeptide were added to a PVP solution containing 2,5-bis(4′-azido-2′-sulfobenzal)-cydopentanone as a photocrosslinking reagent. Using an integrated FET having two ion sensitive elements, an enzyme membrane on the gate surface of one of the two ion sensitive elements was formed by the spin-coating of the enzyme-PVP solution, followed by UV-irradiation on the gate area of the FET and development in a 3% glutaraldehyde solution. The method was used to make enzyme membranes for a urea sensitive and a glucose sensitive FET. Both sensors were evaluated by using a 0.3 ml flow-through cell. The 100% response times were 25 s and 15 s for urea and glucose determination, respectively. The relative standard deviations for determination of urea and glucose with the sensors were less than 2% over the concentration range studied. The application of the urea sensitive FET to ex vivo serum assay is also described. © 1986, The Japan Society for Analytical Chemistry. All rights reserved.