How does the SPR peak respond to change in thickness in water?

simultaneous measurement of SPR curves at two different wavelengthsIn 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".

On use of this animation: Feel free to use this animation for educational purposes. Please, remember to refer to the original source, e.g., BioNavis Ltd - Excellence in Surface Plasmon Resonance, Finland. If you are our customer, remember to request a complementary set of PowerPoint slides about the MP-SPR technology.

See also other animations that explain the SPR curve changes in relation to nanolayer thickness and refractive index change:

How does the SPR peak respond to layer thickness change in thickness in air?


Measure of thick samples (waveguide effect). Thickness up to few micrometers (with light nonabsorbing samples) can be measured. See animation.

How does the SPR peak respond to change in thickness when the sample absorbs light? 


Light absorbing samples, such as porphyrins or gold and silver nanoparticles, cause intensity changes to meaured curves. See animation.