Overview
Surface Plasmon Enhanced common path interferometry (SPE) is a novel detection technology that combines SPR and interferometry in a robust, cost effective platform to provide extremely sensitive label-free biomolecule interaction analysis in a microarray format.
Measurement Principle
The principle is based on measuring index of refraction changes at an affinity layer during exposure to an analyte. This is accomplished by measuring relative phase changes of two components of polarized light within a single beam.
The optical system transforms laser-diode emitted light into s- and p- polarized components within the same beam. Amplitude and phase of each component are tuned for maximum sensitivity. Click on the image to see a Flash demo.
These phase changes are induced by mass increase at the surface that results from the specific interaction of an analyte with the ligand attached to the chip under Total Internal Reflection (TIR) conditions. Any change in the effective index of refraction of the affinity layer, such as through the addition/binding of chemical or biological molecules, generates an optical phase shift, and alters the laser beam’s polarization state.
Comparison of the beam’s two polarization states (s and p) enables detection of minute phase changes, which characterize the rate and extent of the surface interaction to thereby yield information for accurate bio-molecule identification and quantification.
