Theoretical analysis of surface plasmon resonance in capillary sensors

Surface plasmon resonance (SPR) sensors are tending toward miniaturization, and easy-to-use, low-cost sensors are in demand. Here, to meet this demand, we propose a capillary SPR sensor consisting of a capillary with a gold film plated onto the inner wall. A simple ideal model is constructed, cylindrical metal-dielectric waveguide theory is discussed, analytic equations are established, and the SPR curve of the capillary containing water was obtained by calculating the reflectivity. Optical simulations were also carried out in TracePro, and the simulation results are shown to be consistent with the theoretical calculations. Both ideal and Gaussian light sources are studied and small differences in the spectra are compared. Sensor performances and the CCD placement were also discussed. A method of s-polarized light as reference light to eliminating aberration was introduced. The results demonstrate the feasibility of the proposed capillary SPR sensor.