Polarimetric surface plasmon resonance imaging biosensor

We report the realization of a surface plasmon resonance imaging biosensor potentially capable of dynamically characterizing optical anisotropy by means of polarimetric measurements. Our approach relies on a light beam propagating through a high refractive index glass-prism (Kretschmann-Raether configuration) in order to excite a surface plasmon wave along a metal-dielectric interface. This evanescent wave probes the metal-dielectric vicinities with subnanometer sensitivity, thus resolving optical characteristics of adsorbed biomolecular targets. Fixing wavelength and angle of incidence of the beam enables real-time monitoring of adsorptions and desorptions of targets onto the whole surface of the chip, allowing for example characterization of DNA:DNA interaction kinetics with applications to genetic diagnosis. The polarimetric surface plasmon resonance imaging device uses a pyramid of high index glass and two orthogonal SPR imaging sensor arms. The interface is probed along two orthogonal directions. A signal difference in reflection between the two arms should allow us to resolve local optical anisotropy of the dielectric medium, keeping the parallel and real-time capabilities of the system. Additional information can be obtained by varying the angle of incidence of the light beam or tuning its wavelength. We believe that this type of sensor will be useful for studying collective biomolecular assemblies' conformational changes.