| Molecular sensors based on surface enhanced Raman scattering (SERS) and optical fibers have been widely used in biological, environmental and chemical detection procedures due to their unique advantages, such as molecular specificity, high sensitivity and flexibility. In this thesis, I review the development and highlight some of the important milestones of SERS fiber sensor development with emphasis on recent work to improve the sensitivity of the fiber sensors. In particular in the area to increase the sensitivity, we've developed various methods of sample preparation as well as different fiber SERS sensors. One way is to strengthen the field enhancement around the surface of the probe tip and the other is to increase the number of the interacting particles during the SERS process. These techniques are known as the double substrate "sandwich" structure (DSSS) and the liquid core photonic crystal fiber (LCPCF) respectively, and in both cases the sensitivities are significantly improved. The combination of these two mechanisms is also proposed as inner wall coated hollow core waveguide (IWCHCW). As the portable Raman spectrometer is developed and commercially available, a portable fiber SERS sensor system is demonstrated as well in order to make it practical in out of laboratory applications. These fiber sensors were tested with Rhodamine 6G, human insulin, tryptophan, prostate specific antigen, and alpha-synuclein and showed excellent performance. |
