Biosensors are analytical devices incorporating biological materials such as enzymes, tissues, microorganisms, antibodies, cell receptors or biologically derived materials or a biomimic component intimately associated with or integrated within a physicochemical transducer or transducing microsystem which may be either optical, electrochemical, thermometric, piezoelectric or magnetic. The electronic signals produced are proportional to the concentration of specific analyte. A biomaterial may be any material, natural or man-made, that comprises whole or part of a living structure or biomedical device, which performs natural function. An essential component of molecular sensor is reagent layers. Creation of these layers require the immobilization of recognition elements for the detection method. The recognition elements are biomolecules. Laboratory methods of immobilization are numerous, but may not always appropriate for manufacture of biosensors. In the present article, we describe the use of various biomaterials for biosensors as well as their availability. (C) 2002 Elsevier Science B.V. All rights reserved.