DIAMOND-LIKE CARBON COATED MICROPOROUS POLYCARBONATE AS A COMPOSITE BARRIER FOR A GLUCOSE ENZYME ELECTRODE

Diamond-like carbon (DLC) coated microporous polycarbonate membranes were used as outer covering membranes in glucose enzyme electrodes. With optimised DLC deposition and the use of 0.01 mum microporous polycarbonate, biocompatability has been seen to improve with only a loss of 6% response after 30 min exposure to whole blood, and a correlation to within 1 mM concentration with a standard laboratory method. In addition, control of the coating process allowed substrate diffusion-limiting properties to the bulk enzyme to be finely tuned permitting extensions in linearity ranges from 5 to > 80 mM glucose. Furthermore the higher biocompatability coupled with the degree of permselectivity exhibited by DLC has enabled operation within whole blood without a second hydrogen peroxide selective barrier membrane. Permeability coefficients of glucose and O2 determined for corresponding membranes by a classical diffusion chamber technique suggest that both the glucose/O2 permeability coefficient ratios and the absolute glucose permeability influenced the linearity range.