Cavity plasmon resonance biosensing

Surface plasmon resonance (SPR) spectroscopy has demonstrated unprecedented performance in label-free real-time probing of various biopolymer, ligand, protein, and DNA interactions. Since its inception in the late sixties, the basic physical phenomenon underlying the SPR biosensing remained unchanged, namely, resonant absorption of TM-polarized light incident upon a metallic nanofilm above the critical total internal reflection angle. Since the SPR field is strictly confined to the metal-analyte interface, the measurements are usually limited to molecular adsorbates located in an immediate vicinity of this surface. Herein, we propose a novel biosensing method utilizing cavity plasmon resonance (CPR) excitation in nanofilms. As opposed to the classical TM-polarized SPR, the CPR is applicable for both TE and TM polarizations and does not require complicated evanescent field excitation conditions. It holds a promise for highly sensitive real-time probing of scalable amounts of analytes in a variety of frequency bands.