Characteristics of a paired surface plasma waves biosensor

A novel paired surface plasma wave biosensor (PSPWB) is described and setup. By integrating the features of a common-path optical heterodyne interferometer and the amplitude-ratio detection mode, the PSPWB not only produces a high detection sensitivity but also provides a large dynamic measurement range for effective refractive index (Δn_eff) based on amplitude-sensitive detection method. Thus, the performance of PSPWB becomes equivalent to shot-noise limited of a conventional SPR biosensor. To our knowledge, this novel PSPWB shows the highest detection sensitivity on Δn_eff when compared with conventional SPR biosensors using either a non-interferometric or interferometric technique. The experimental results correctly verify the properties of a PSPWB that the detection sensitivity is an order of 10^-7 refractive index unit (RIU) when measuring a 0.001% sucrose-water solution. This result confirms the detection sensitivity up to 10^-9 RIU of the IgG/anti-IgG interaction in real time successfully. Furthermore, a dynamic range of 105 using PSPWB was also obtained.