How does MP-SPR work?

The Material Science perspective: From drug discovery to Ångström precision in coatings and material development.

For the past 20 years, SPR has been used for biomolecular interaction analysis. Now, MP-SPR broadens the application range to material characterization. Surfaces of metals and biomaterials, such as ceramic or polymer coatings, can be characterized with Ångström precision.

The key to the Multi-Parametric Surface Plasmon Resonance is the measurement of full SPR curves. When measured as a function of time (with sampling rate of one curve every few seconds), the results can be calculated to many different physical parameters describing the sample properties or interactions.

True thickness: Thickness and Refractive index (RI) can be determined by fitting of curves using Fresnel formalism. With additional lasers, a singular solution can be found without known RI or thickness.
From Å to µm: Unique wide angle range measurement enables measurement not only of thin layers (Ångströms) but also thicker layers up to a few micrometers.
No vacuum required: The method allows measurements of samples in air, in a specific gas, humidity or in liquid environment.
Real-time interactions: MP-SPR is a real-time method and therefore, allows for instance measurements of swelling of materials when moving from dry to wet environment. It also provides real-time data on material-solvent interactions, for instance.

Above, you can see an animation of a full SPR curve scan.
The graph shows a shift in SPR due to formation of a layer at the surface. The new layer can be formed in-situ or ex-situ. The x-axis is the angle at which the laser excites plasmons. The y-axis shows the level of light intensity reflected from the surface. The dip in the curve (lowest light intensity) shows, when the plasmons are excited. Full SPR curves are used to obtain physical properties of the layer.