%0 Journal Article %T An Approximate Analytical Method for the Evaluation of the Concentrations and Current for Hybrid Enzyme Biosensor %A Indira Krishnaperumal %A Rajendran Lakshmanan %J ISRN Physical Chemistry %D 2013 %R 10.1155/2013/202781 %X Mathematical modeling of amperometric biosensor with cyclic reaction is discussed. Analytical expressions pertaining to the concentration of substrate, cosubstrate, reducing agent and medial product and current for hybrid enzyme biosensor are obtained in terms of Thiele module and saturation parameters. In this paper, a powerful analytical method, called homotopy analysis method (HAM) is used to solve the system of nonlinear differential equations. Furthermore, in this work the numerical simulation of the problem is also reported using Scilab/Matlab program. Our analytical results are compared with simulation results. A good agreement between analytical and numerical results is noted. 1. Introduction Biosensor (Figure 1) is a device that uses specific biochemical reactions mediated by isolated enzymes, immunosystems, tissues, organelles, or whole cells to detect chemical compounds usually by electrical, thermal, or optical signals [1]. They involve a biological (recognition) element and a transduction element. The biological or recognition element may be an antibody, an enzyme, DNA, RNA, a whole cell, or a whole organ or system. The transduction element, wherein the biological event or signal is converted to a measurable signal, may include anyone of the following forms: chemical, electrical, magnetic, mechanical, optical, or thermal. Figure 1: Basic scheme of a biosensor [ 1]. The biosensor was first described by Clark and Lyons in 1962, when the term enzyme electrode was adopted [2]. The term ¡°biosensor¡± was introduced by Cammann in 1977 [3]. Since then, research communities from various fields such as physics, chemistry, and material science have come together to develop more sophisticated, reliable, and mature biosensing devices for applications in the fields of medicine, agriculture, biotechnology, as well as in the military for bioterrorism detection and prevention [4]. Biosensors offer the prospects of simplified, virtually nondestructive analysis of turbid biological fluids. Also, biosensors for medical care have demanded the greatest attention for technical development [5]. Amperometric electrodes have been used in the design of biosensors for glucose, aminoacids, and other molecules [6¨C9]. In cases of amperometric enzyme biosensors the potential at the electrode is held constant while the current flow is measured. Amperometric biosensors are quite sensitive and more suited for mass production than the potentiometric ones [10, 11]. Electropolymerized films offer wide immobilization capabilities and extremely large diversity in the development %U http://www.hindawi.com/journals/isrn.physical.chemistry/2013/202781/