What is surface plasmon resonance?

Surface plasmon resonance (SPR) is an optical detection process that can occur when a polarized light hits a prism covered by a thin metal layer. Under certain conditions (wavelength, polarization and incidence angle) free electrons at the metallic surface of the SPRi-Biochip absorb incident light photons and convert them into surface plasmon waves. These waves are penetrating the medium above the surface within 100 to 200 nm. At a specific incidence angle (called resonance angle), the plasmon waves resonate with the incident light, resulting in a dip of reflectivity. The plasmon curves show the variations of the reflected light collected on the CCD camera versus the incidence angle. The position of the resonance angle is very specific of the local environment of the SPRi-Biochip surface.

Perturbations on the SPRi-Biochip surface (within about 200 nm), such as an interaction between ligands and analytes, induce a modification of resonance conditions, which can be measured.

Principle of SPRi
Principle of SPRi