A flux limiting layer for an intravenous amperometric biosensor is formed on a substrate to limit a diffusion rate of an analyte from blood to an enzyme electrode. The layer may be formed from ethylene vinylacetate (EVA) dissolved in a solvent such as paraxylene, spray-coated to cover a portion of the electrode, and cured to seal the electrode to the substrate. In a glucose sensor having glucose oxidase disposed on the electrode, thickness and concentration of the EVA layer are optimized to promote a linear output of electrode current as a function of blood glucose concentration.
