INTEGRATED DIFFERENTIAL ENZYME SENSORS USING HYDROGEN AND FLUORIDE-ION SENSITIVE MULTIGATE FETS

Enzyme field effect transistors (ENFETs) were assembled by immobilizing enzymes to a multigate proton and fluoride ion sensitive field effect transistor. All the six gates and two thin film noble metal electrodes (TFME) at the chip have been covered by crosslinked polyurethane entrapping the enzymes. Two variations of difference mode measurements of glucose have been realized. The difference of the output voltages of a pH-ENFET and a pF-reference FET (REFET) or the difference output voltages of a pF-ENFET based on a glucose oxidase/peroxidase-catalyzed reaction liberating fluoride ions and a pH-REFET are measured using the integrated TFME as pseudo-reference. Besides the convenient handling of the devices, the homogeneous coverage of the active area of the chip simplifies the construction and production of ENFETs. © 1990.