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Theoretical analysis corresponding to the diffusion and kinetics of substrate and product in an amperometric biosensor is developed and reported in this paper. The nonlinear coupled system of diffusion equations was analytically solved by Homotopy perturbation method. Herein, we report the approximate analytical expressions pertaining to substrate concentration, product concentration, and current response for all possible values of diffusion and kinetic parameters. The numerical solution of this problem is also reported using Scilab/Matlab program. Also, we found excellent agreement between the analytical results and numerical results upon comparison.

Theoretical modeling of biosensors usually provides some important insight into understanding the functioning of a biosensor. Usually, with the aid of an analytical device, it is not possible to measure the concentration of substrates inside the enzyme membranes. As a result, theoretical model in biosensors has been developed and employed as an important tool to study the analytical characteristics of biosensors. Initially, Goldman et al. [

Catalytic biosensors are sensors that use enzymes which catalyse a specific conversion of analyte [

Amperometric biosensors are rapid, sensitive, and highly stable candidates for environmental, clinical, and industrial applications. The general features of amperometric biosensors have been studied and analyzed extensively in the literature [

Recently, Coche-Guerente et al. [

The complete mathematical formulation of this problem is described in Coche-Guerente et al. [

Schematic representation of rotating disk electrode modified by a PPO enzymatic layer and principle of the bioelectrode functioning in the presence of phenol substrates

The HPM [

The system of steady-state nonlinear differential equations (

Equations (

The profile of the normalized concentration of phenol substrate

The profile of the normalized concentration of catechol substrate

The profile of the normalized concentration of

The analytical expression of steady-state current

The steady state-current

This paper reports a mathematical treatment for analyzing amperometric enzymatic reactions. In this paper, we have evaluated a theoretical model for a rotating disk electrode based on an immobilized enzyme layer. The novelty of this paper is an application of approximate method to the second-order nonlinear partial differential equations. The approximate analytical expressions for the steady state substrate concentrations and product concentration profiles for all values of

In this appendix, we indicate how (

function pdex4

m = 0;

Concentration of the phenol substrate (mole

Concentration of the catechol substrate (mole

Concentration of the

Bulk concentration of the phenol substrate (mole

Bulk concentration of the catechol substrate (mole

Bulk concentration of the

Enzyme concentration (mole

Thickness of the enzymatic layer (cm)

Thickness of the diffusion-convection layer (cm)

Diffusion coefficient in the enzymatic layer (

Diffusion coefficient in the diffusion convection layer (

Reaction lengths (cm)

Kinetic parameters (mole

Kinetic parameters (

Ratio of the square of thickness of the enzymatic layer and the reaction length (None)

Ratio of the square of thickness of the enzymatic layer and the reaction length (None)

Dimensionless parameter (None)

Dimensionless parameter (None)

Ratio of the thickness of the enzymatic layer and the thickness of the diffusion-convection layer (None)

Faraday constant (None)

Normalized concentration of the phenol substrate (None)

Normalized concentration of the catechol substrate (None)

Normalized concentration of the

Dimensionless current (None).

This work was supported by the University Grants Commission (F. no. 39-58/2010 (SR)), New Delhi, India. The authors are thankful to Dr. R. Murali, The Principal, The Madura College, Madurai, and Mr. M. S. Meenakshisundaram, The Secretary, Madura College Board, Madurai, for their encouragement. They also thank the reviewers for their valuable comments to improve the quality of the paper. The author K. Indira is very thankful to the Manonmaniam Sundaranar University, Tirunelveli, for allowing to do the research work.