Recently, research in the area of biosensors has grown rapidly due to the need of miniaturization, mass production, accurate analysis and prompt measurement felt by the users community [1]. A biosensor is an analytical device combining a biological molecule and a physical transducer. The biological molecule acts as sensing element (recognition element), while the transducer produces an electrical or optical signal output proportional to the analyte concentration. We used the Glucose Oxidase (GOD) extracted from the Aspergillus niger, as recognition element. It is an enzyme and catalyzes the BD-glucose oxidation in 6-gluconolactone and the molecular oxygen reduction in hydrogen peroxide. GOD is a dimeric protein with a molecular weight of 160 KDa (80 KDa per monomer) and dimension of 7nm x 5.5 mm x 8mm. Each monomer binds a FAD cofactor, which acts as a redox carrier in catalysis, with a noncovalent bond [2-3]. The polypeptide chain of each monomer has 538 amino acid residues [4]; three of these amino acid residues are cysteins: two are involved in disulfide bonds, while the third is a free thiol group [5]. This enzyme is used to monitor the glucose concentration in the blood [6]. For this reason, GOD is used for the fabrication of macro and, tentatively, micro glucose biosensors. A miniaturized glucose sensor could have immediate applications to diabetes monitoring. We tested and optimized a protocol to immobilize the GOD on bulk SiO2 and, subsequently, on porous silicon dioxide (PSiO2). The choice of Si-based materials as inorganic platforms is due to the fact that Si has a mature and low cost technology and offers the …