SILICON-WAFER INTEGRATED ENZYME REACTORS

Enzyme reactors were fabricated on silicon wafers using microstructuri ng technologies. The reactors were made of several parallel vertically -cut flow channels. The reactor structures occupied a wafer area of 3 15 mm. Reactors with two different channel densities were fabricated : 10 channels/mm, 165 mu m deep; and 25 channels/mm, 235 mu m deep. Gl ucose oxidase was immobilised on the reactors and their corresponding enzyme activities were monitored by a colourimetric assay. It was show n that a reactor surface area increase of 3 times gave rise to a propo rtional enzyme activity increase in the reactor. The maximum glucose t urnover rate for the reactor with 25 channels/mm was approximately 35 nmol/minute and the corresponding apparent K-m was approximately 17 mM . A wafer integrated enzyme reactor was also operated in a microdialys is-based system for continuous glucose monitoring, showing a linear re sponse up to 4 mM glucose.