Abstract
A differential detection method and a modulated semiconductor laser have been developed for a surface plasmon resonance (SPR) biosensor. By using this method, the influence of sample backgrounds, e.g., its composition or temperature, can be cancelled and immunoreactions can accurately be measured in real time. Moreover, using the modulated laser, we can diminish the influence of noise from background light and amplify output signals to a favorable level. The sensitivity of the sensor can thus be improved. Using such an SPR biosensor system, we have been able to detect α-Fetoprotein of a few ng/ml.
