Don’t stay in the dark, see more with MP-SPR!
Unlike traditional SPR configuration, the technology behind MP-SPR offers a superior exploration level on analyzed samples. MP-SPR is not only capable of measuring molecular interactions but provides additional insights into sensor layer properties. This unique capacity opens up numerous applications in material sciences by enabling detailed characterization of functional coatings like self-cleaning surfaces, antimicrobial materials or filter membranes. MP-SPR can elucidate fundamental research questions and assist in development of new biosensing or diagnostic devices. The technology can be efficiently applied as R&D or QC tool in the field of display technologies, semiconductors, solar panels and batteries.
Calculating thickness and refractive index from MP-SPR data
MP-SPR can be used to determine true layer thickness and refractive index (RI) without prior knowledge of either parameter. The technology enables to monitor in real time the optical properties of films generated over the sensor surface in both gas and liquid environments. Thickness and RI are measured simultaneously using the unique optical configuration based on multiwavelength detection and wide angular scan. The obtained MP-SPR curves are mathematically modelled according to Fresnel equations resulting in detailed information on optical properties of layers. Curve fitting is enabled by a dedicated software MP-SPR Navi™ LayerSolver. MP-SPR has been successfully applied to study a wide range of materials: from non-transparent films (metals, metal oxides, graphene) and nanomaterials (nanocellulose, gold nanoparticles) up to different polymers, lipid membranes and biological layers (e.g. live cells).
MP-SPR response to change in thickness in air?
While traditional SPR is suited only for measurements in liquid (range of 1.33 to 1.38 of RI, which corresponds roughly to 65 to 75 degrees of angular range), MP-SPR works also in air (range of 1.0 to 1.45 of RI, which corresponds roughly to 38 to 78 degrees of scanning angular range). Air and liquid range is measured without any change in the instrument setup. This animation also shows a formation of a waveguide for thicker nanolayers. MP-SPR is ideally suited for dynamic measurements of material swelling and conformational change, e.g. from dry to wet state.
MP-SPR response to change in thickness in water?
In this animation, you can clearly see, what happens to SPR curves when measuring nanolayers in liquid. While the first SPR peak disappears when the nanolayer thickness reaches 150 nm, it appears again and forms a waveguide (showing as multiple peaks in the graph). Traditional SPR measures only in the range of 1.33 to 1.38 of RI (which corresponds roughly to 65 to 75 degrees of angular range), limiting its operation to thin layers only. From this animation it is clear, how MP-SPR is able to measure transparent layers, such as polymers or living cells, that are even several microns thick.
Note: Surface measured with two different wavelengths (here 785 nm and 670 nm). Both measurements are done simultaneously from the same spot, meaning that the thickness of the sample is the same. The difference in the shape of the curve is due to the difference in refractive index in relation to the measurement wavelength. Lower wavelengths are more sensitive, however, they have smaller “working range”.
SPR peak response to change in thickness when the layer absorbs light?
The animation on the left shows what happens to the SPR curve when nanolayer thickness is increased and the nanolayer is light absorbing (i.e. has a complex refractive index). The SPR curve peak starts diminishing (moving upwards) upon thickness increase of e.g. metal layers.