Considerations for Improving the Performance of Surface Plasmon Resonance Biosensors

There are four types of currently used SPR biosensors for the detection of biomolecular interaction. Their sensitivities and noise immunity based on angular and wavelength interrogation are calculated and compared. The results show that the conventional SPR biosensor which takes the advantage of the highest sensitivity suffers the worst noise immunity among all the SPR biosensors. Although the WCSPR biosensors has a better noise immunity than the conventional SPR, it nevertheless exhibits inferior noise immunity to the LRSPR and CPWR biosensors because of their very narrow dips in the reflection curves. Under angular interrogation, the noise limited resolutions of the LRSPR and CPWR biosensors are higher than that of the other two types; while the LRSPR has the highest resolution for wavelength interrogation. The influence of the probe beam divergence is also discussed. The divergence has more serious effect on the sensor which has narrower and sharper dip and results in the shift of the resonance position and the broadening of the FWHM, which decays the noise immunity of the sensor.