Sensitivity improvement of polypyrrole-based urea sensor using copper ion doping effect

The functionalization of an integrated urea sensor by a copper-poly pyrrole matrix doping urease molecules and its application to the amperometric detection of urea is described. Copper cluster was doped into polypyrrole matrix to increase electrical conductivity. Urease was electroadsorbed onto this conductive matrix. The comparison of different organic and inorganic host matrices in terms of storage and operational stabilities clearly demonstrated the advantages of the composite matrix. Pt thin film electrode fabricated on silicon substrate by the radio frequency sputtering and titanium layer is also deposited as an underlayer to increase adhesive strength. The copper-doped polypyrrole and polypyrrole films are coated on platinum thin film electrode by cyclic voltammetry, respectively. Under the optimized condition, the limiting current obtained from the copper-doped polypyrrole urea sensor is proportional to the urea concentrations with the slope of 4.5 microampere per decade, which is two times higher sensitivity value than that of the polypyrrole urea sensor. In addition, the electrode surface was analyzed by scanning electro microscopy.