Label-free biosensing using a nanostructured Fabry-Perot interferometer

This paper reports a novel label-free biosensor based on a nanostructured Fabry-Perot interferometer (FPI) for the first time. Au-coated nanostructure layer inside the FPI offers significantly enhanced optical interference signals due to localized surface Plasmon resonance (SPR) effect. Immobilization of capture protein, Protein A, on the nanostructure layer and its binding with immunoglobulin G (IgG) inside the FPI are monitored in real time, resulting in interference fringes shift of the signals. Fourier transform (FT) is performed on the measured reflectance interference spectrum. Only a single peak whose X-axis position is the effective optical thickness (EOT) of nanostructured layer is presented for each spectrum, which simplifies the quantified analysis of the signals. Current results show that the detection-of-limit (DOL) of the biosensor should be much lower than 5ng/ml.