Enzyme biotransducers formed from conductive electroactive polymers

Three types of biotransducer devices were studied: an enzyme Field Effect Transistor (Enz-FET), an interdigitated microsensor electrode (IME) array for impedimetric detection, and a microdisc electrode array for amperometric detection. Each device type was microlithographically fabricated from a pattern of sputter deposited metal (10 nm Ti/W 100 nm Pt or Au) on an insulating substrate that was either glass or oxidized p-type silicon. Insulating regions were fashioned from Si₃N₄ and the gate dielectric of the FET was a SiO₂ layer of 100 nm thick spin-on glass. For each biotransducer device type, the enzyme glucose oxidase (GOx) was immobilized using a process of electropolymerization of pyrrole (0.8 V vs. Ag/AgCl) in the presences of glucose oxidase (1 mg/ml) in deionized water to achieve a total of 100 mC/cm². The dose-response characteristics of each of the biotransducers were tested in muta-rotated glucose solutions (PBS 7.2) at RT that ranged from 0.0 mM to 20 mM. The sensitivity (m=slope), linear dynamic range and limits of detection [3(SD_blank/m)] were calculated from replicate measures of the dose response curve.