Surface Plasmon Resonance enhanced Common Path Interferometry for high sensitivity label free biomolecule interaction analysis

A biomolecule interaction detection system using common path interferometry enhanced by surface plasmon resonance has been developed that provides multiplexed label free detection of biomolecule analytes at unprecedented sensitivities. Differential phase analysis of two orthogonally polarized components of a single laser beam gives interferometric measurement of refractive index changes at a biosensor surface. Surface plasmon resonance enhances the phase differential to give ultimate sensitivity below 5times10^-8 RIU. Discreet two dimensional area analyses within the laser beam allow simultaneous interrogations of multiple analytes in a microarray format by using diode array detectors optically aligned with elements on the transducer. Preliminary results establish current sensitivity and dynamic range, and demonstrate detection of proteins and whole organisms such as bacteria. Differential signal acquisition from a multi-diode array with specifically functionalized transducers demonstrates multiplexed microarray analysis.