Optical sensors. Part 34. Fibre optic glucose biosensor with an oxygen optrode as the transducer

Abstract

A biosensor for the continuous determination of glucose is presented. Glucose oxidase was immobilised covalently on a nylon membrane and the consumption of oxygen was measured by following, via fibre optic bundles, the changes in the fluorescence of an oxygen-sensitive dye whose fluorescence is quenched dynamically by molecular oxygen. The dye is dissolved in a very thin silicone membrane placed beneath the enzyme layer. As a result of the oxidation by the enzyme a certain amount of oxygen is consumed. This amount is indicated by the fluorescent dye. The measurements were performed in flowing air-saturated solutions containing 0.1 M pH 7.0 phosphate buffer. The effects of the amount of immobilised enzyme and the thickness of the indicator layer on response times (t90= 1–6 min), analytical ranges (0.1–20 mM) and relative signal changes (up to 26%) were investigated.