Chemical and biological detection using microfluidic platform and surface plasmon resonance imaging sensor

A microfluidic platform integrated with a high-sensitivity surface plasmon resonance (SPR) imaging sensor based on Mach-Zehnder interferometer design is presented. The disposable polydimethylsiloxane (PDMS)-based microfluidic platform consists of four independent flow chambers that can be detected four different concentrated solutions by SPR imaging biosensor simultaneously. The novel feature of the SPR imaging biosensor is the use of a Wollaston prism through which the phase quantities of the p and s polarizations are interrogated synchronously. Since SPR affects only the p polarization, the signal due to the s polarization can be used as the reference. Consequently, the differential phase between the two polarizations allows us to eliminate all common-path phase noise while keeping the phase change caused by the SPR effect. Two experiments were conducted: 1) detecting different concentrations of salt-water mixtures, and 2) monitoring the reaction between BSA-BSA antibody. This technique is shown here to have a sensitivity of 0.44/spl mu/g/ml for salt-water mixture. Given that we have now demonstrated the possibility of SPR phase extraction from digitized images, direct application of this technique in two-dimensional (four independent flow chambers) sensor arrays with high measurement throughput is also suggested.