Abstract: The amperometric sensor comprised Pt and Ag/AgCl working and reference electrodes, respectively. Glucose oxidase was embedded in a polyurethane layer between two membranes and on top of this membrane sandwich Cuprophan or bacterial cellulose were attached by an O-ring. Glucose oxidase reaction products were detected at +600 mV. Measurements were made on heparinized undiluted blood and blood diluted tenfold. Cuprophan containing membranes were stable for 3-4 h whereas bacterial cellulose membrane electrodes were stable for >24 h. The linearity of the biosensor was extended by coating the membranes with 1-3 layers of polyamide from 0-3 mM to 5-170 mM glucose. Samples are analyzed using an FIA experimental set-up (schematic diagram given).