Integrated-optic surface-plasmon-resonance biosensor using gold nanoparticles by bipolarization detection

A new integrated-optic surface-plasmon-resonance (SPR) biosensor using gold nanoparticles with the ability of bipolarization interrogation is demonstrated. Although the previous SPR biosensor using gold nanoparticles can excite the surface plasma wave by the TM- and the TE-polarized lightwave, the sensitivity to the environmental index change for the TE-polarized lightwave is too low to be useful. The new integrated-optic SPR biosensor with a ridge waveguide structure can produce the obvious SPR wavelength shifts varied with the analyte concentration for two orthogonal polarizations. Therefore, two kinds of analytes can be separately detected by the TM- and the TE- polarized modes in one SPR biosensor, and the number of detectable biomaterials by the biosensor array in one chip can be doubled. This SPR biosensor is designed for the concentration measurement of beta-blocker, which is a remedy for heart disease. In the linear operation range, the SPR wavelength increases with the concentration of beta-blocker at a rate of 0.073 and 0.029 nm/ppm for the TM- and the TE- polarized modes, respectively.