**1. Introduction**

The unprecedented interest in the development and exploitation of analytical devices for detection, quantification and monitoring of specific chemical species has led to the emergence of biosensors.Electrochemical biosensorshave gainedever-increasing acceptance inthe fieldof medical diagnostics, health care, environmental monitoring, and food safety due to high sensitivity, specificity, and ability for real-time analysis coupled with speed and low cost and polymers are promising candidates that can facilitate a new generation of biosensors [1-7]. A biosensor is a device having a biological sensing element either intimately connected to or integrated within a transducer. The aim is to produce a digital electronic signal, which is proportional to the concentration of a specific chemical or set of chemicals (Fig. 1). A definition of biosensor is proposed by IUPAC as: "a self-contained integrated device, which is capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition element (biochemical receptor), which is retained in direct spatial contact with a transducer element." The life time of the enzyme electrode, the rate of electron transfer be‐ tween the enzymatic redox reaction and electrode, and the miniaturization of enzyme elec‐ trode are some of the critical points appeared as central to this interdisciplinary research. Biosensor has been pursued extensively in a wide range for their unparalleled selectivity and mild reaction conditions. As a coin has two sides, enzymes which are the key biological recognition element are usually costly and easy to inactivate in their free forms. The immobili‐ zation of enzymes is the main approach to optimizing the in-service performance of an en‐ zyme, particularly in the field of non-aqueous phase catalysis. However, the immobilization processforenzymeswillinevitablyresultinsomelossofactivity,improvingtheactivityretention oftheimmobilizedenzymeiscritical.Tosomeextent,theperformanceofanimmobilizedenzyme is mainly governed by the supports used for immobilization, thus it is important to fully understand the properties of supporting materials and immobilization processes [8-10]. The properties of immobilized enzymes are governed by the properties of both the enzyme and the support material. The interaction between the two lends an immobilized enzyme specific physico-chemical and kinetic properties that may be decisive for its practical application, and

© 2013 Wang and Uchiyama; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Wang and Uchiyama; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

thus, a support judiciously chosen can significantly enhance the operational performance of the immobilized system. It is widely acknowledged that analytical sensing at electrodes modified with polymeric materials results in low detection limits, high sensitivities, lower applied potential, good stability, efficient electron transfer and easier immobilization of enzymes on electrodes. In recent years, there has been growing concern in using polymeric materials as supports for their good mechanical and easily adjustable properties [11]. Of the many carriers that have been considered and studied for immobilizing enzymes, conducting polymer (CP), redox polymer (RP), sol-gel and hydrogel materials, chitin and chitosan are of interest in that they offer most of the above characteristics [12, 13].

Theproperuseofdifferentcompositionsofbinderandimmobilizationmatrix,electrontransport mediators, biomaterials and biocatalysts, and solid supports as electron collectors in the construction of enzyme electrode is critical to generate optimum current from the enzymatic redox reactions. In essence, design and fabrication of advanced materials coupled with good understandingoftheirbehaviorswhenincorporatedasinterfacialortransducerelementswould be of paramount importance. The recent advancement of polymer materials is greatly influenc‐ ingthe redox reactions andelectrontransportkineticsofthe enzyme electrodes.Toachievehigh specificity, high sensitivity, rapid response and flexibility of use, it is clear that the research continues to focus on new assembly strategies. Polymers are becoming inseparable from biomolecule immobilization strategies and biosensor platforms. Their original role as electri‐ cal insulators has been progressively substituted by their electrical conductive abilities, which opens anew andbroadscope of applications.This chapterhighlights recent contributions inthe incorporationofpromisingpolymericmaterialswithinbiosensors, specialemphasiswasplaced ondifferentclassesofpolymericmaterialssuchasnanomaterials,sol-gelandhydrogelmaterials, conducting polymers, functional polymers and biomaterials that have been used in the design of sensors and biosensors. We want to remind our readers that this chapter is not intended to provide comprehensive coverage of electrochemical biosensor development but rather to provide a glimpse of the incorporation of polymers within biosensors. These materials have attracted much attention to their potentials for interesting applications, broad applicability as well as tunableproperties accordingto applicationsneeds.Inaddition,the criticalissues related to the fabrication of enzyme electrodes and their application for biosensor applications are also highlighted in this article. Effort has been made to cover the recent literature on the advance‐ ment of polymers to develop enzyme electrodes and their potential applications for the construction of biosensors [14-15].

**Figure 1.** Principle of biosensor
