Evanescent Wave Absorption Based S-shaped Fiber-optic Biosensor for Immunosensing Applications

In this study, S-shaped multimode fiber-optic probe have been employed to improve sensitivity of evanescent wave absorption (EWA) based fiber-optic biosensor. Immunosensing was performed using Human immunoglobulin (HIgG) and fluorescein isothiocyanate (FITC) tagged Goat anti-human immunoglobulin (GaHIgG) antigen-antibody pair. The immunosensing was carried out in direct ELISA format, with the exception of replacing enzyme with FITC as reporter molecule. In an earlier study, we have observed higher EWA sensitivity and refractive index (RI) sensitivity for S-shaped compared to U-shaped fiber-optic probe [1]. The fabricated S-shaped geometry improved the lowest measurable concentration of GaHIgG biomolecule to 1.7 nM. The proposed immunosensor showed negligible non-specific binding on the sensor surface, thereby improving the detection accuracy.