Insights into the Performance-Determining Aspects of Electrochemical Biosensor Strips by Diffusion Profile Visualization using Finite Element Method Simulation

Abstract

Substrate diffusion was proposed as the rate-limiting step in a recently reported glucose sensor strip bearing a water-soluble quinone mediator with high enzyme reactivity. This mechanism is expected to lead to sensors requiring smaller mediator amounts but having higher sensitivity and a wider measurement range than conventional sensor strips containing mediators with low enzyme reactivity. A general finite element method-based simulation model for mediator-type enzyme electrodes was used in this study to obtain the concentration distribution profiles of this specific glucose sensor strip and clarify its action mechanism. The obtained profiles showed that the mediator forms a very thin diffusion layer on the electrode surface and that the diffusion layer in the substrate gradually covers the entire solution. The results confirmed that the rate-limiting step of the glucose sensor strip is substrate diffusion.