Comparative study of two measurement/modeling techniques for biodevices functionalization assessment in agri-food applications

In this work we have analyzed and compared two techniques for label-free biosensors characterization: Surface Plasmon Resonance (SPR) and Electrochemical Impedance Spectroscopy (EIS). We have been able to quantitatively characterize both thickness and surface coverage of deposited Self Assembled Monolayers (SAM) produced with molecules of different lengths and concentrations. To this purpose, we have performed both SPR and EIS measurements on nominally identical nanostructured devices functionalized with the same protocols. The experimental results are in general agreement between the two methods, with some differences related to the different sensitivity to details of the surface coverage. Exploiting also the complementary capabilities of SPR and EIS can help developing reliable in-field characterization methods of label free biosensors, such as in agri-food applications.