Insights into the performance-determining aspects of electrochemical biosensor strips by diffusion profile visualization using finite element method simulation

Abstract

The rate-limiting step in a recently reported glucose sensor strip incorporating a water-soluble quinone mediator with high enzyme reactivity was proposed to be substrate diffusion. This mechanism is expected to lead to sensors requiring smaller mediator amounts but possessing 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 employed 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 of the substrate gradually covers the entire solution. The results of this study confirmed that the rate-limiting step of the glucose sensor strip is substrate diffusion.