LSPR Phenomenon Description
Insplorion’s technology Nanoplasmonic Sensing (NPS) exploits a physical phenomenon called Localized Surface Plasmon Resonance (LSPR).
Introduction to Localized Surface Plasmon Resonance (LSPR)
The LSPR is a coherent, collective spatial oscillation of the conduction electrons in a metallic nanoparticle, which can be directly excited by near-visible light. The LSP resonance condition (i.e. the wavelength/color of light which can excite the LSPR) is defined by a combination of
- the electronic properties of the nanoparticles
- the nanoparticle size and shape
- the nanoparticle temperature
- the dielectric environment in close proximity of the nanoparticles
The latter is a consequence of the locally enhanced plasmonic near field (with respect to the incoming field), exponentially decaying from the nanoparticle surface. Within this “nanovolume” of locally enhanced field, small changes in the local dielectric environment (e.g. caused by molecular adsorption) affect the LSPR, which is manifested as changes in the amount of scattered and/or absorbed light at different wavelengths. These changes can be measured with high spectral resolution, in a simple optical transmission or reflection experiment, making LSPRs excellent nano-sensors.