Conductometric urea sensor. Use of additional membranes for the improvement of its analytical characteristics

Urea-sensitive enzymatic conductometric biosensors based on interdigitated gold electrodes were prepared by cross-linking urease with bovine serum albumin in a saturated glutaraldehyde vapour on the sensor chips. Additional Nafion or PVP (poly(4-vinylpyridine-co-styrene)) membranes were deposited on top of the urea microsensor by a spin-coating process. The main analytical characteristics (dynamic range, buffer concentration sensitivity) of these urea-sensitive microconductometric devices were not significantly modified by the use of Nafion additional membranes. Better results were obtained for sensors coated with PVP additional membranes: their operational storage stability and reproducibility are promising for further applications, especially in the biomedical field.