Mathematical Model and Fabrication of Multi-Layer Electrochemical Glucose Sensors

Abstract

The design and fabrication of multi-layer amperometric electrochemical glucose sensors is dependent upon the diffusional kinetics of the chemical/biochemical species which contribute to the sensor’s response. Considerable effort has been carried out to coat the working electrode with appropriate glucose flux-limiting membranes which is pertinent for superior in vivo performance, and hence requires a careful understanding of the participating species within the sensor cross-sectional architecture. This contribution reports the computational modeling of Clark’s first generation amperometric glucose sensor coated with an electro-polymerized glucose oxidase (GOx) layer along with a layer of polyurethane (PU) employed to reduce the glucose-influx in order to generate linear operation over the normal physiological glucose range in vivo. The model was programmed using MATLAB and utilizes the finite-difference method for the solution to the enzymatic reaction-based diffusion equations. Additionally, experimental devices were fabricated, tested and compared with the simulated results. The simulation of these devices have been shown to align well with experimentally fabricated devices in terms of amperometric current density. The increase in device linearity with the addition of the outer glucose-flux limiting PU membrane corroborate our experimental findings reported in this study which can be used as a powerful analytical tool in designing high–performance next generation implantable glucose sensors.

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“…Our simulation model relies on the following simplifications: the three free species, namely glucose, O 2 , and H 2 O 2 , obey Fick's diffusion laws, and reactions among them are isothermal. [ 29–31 ] GOx and PB NPs, about 50 nm in size, are alternately and uniformly distributed on the film with separation distances of about 100 nm based on SEM images. 2D cross‐section concentration profile is used to represent 3D concentration profile.…”

“…The simulation details including all parameters used are given in Figure S2 and Table S1, Supporting Information. [ 30,32 ]…”