TRANSIENT-RESPONSE OF MULTILAYER ELECTROENZYMATIC BIOSENSORS

A numerical model is used to analyze the transient response of amperom etric enzyme sensors. Different biosensor types are considered accordi ng to whether the enzyme is fixed on the inner or the outer surface or inside the membrane itself. The numerical simulation is performed wit h a finite volume method which makes it possible to easily solve the t ransient mass balance equations in all the juxtaposed layers of the bi osensors. Phenomena induced by the transient mass transfers in the dif ferent layers are emphasized particularly by analyzing the effects of the stirring strength and the assay protocol on the shape of the curre nt-time curves. This makes it possible to suggest theoretically signif icant opportunities to improve the reliability and performance of bios ensors. The peak current, which appears in some cases when stirring is decreased, offers a measure that is faster and less sensitive to the operating conditions than the steady-state value. After determination of a maximum number of physicochemical parameters by independent exper iments, the model satisfactorily fits experimental results performed w ith free enzyme and immobilized enzyme sensors.