Fabrication And Application Of Silver-based Fiber-optic Surface Plasmon Resonance Sensors

Surface plasmon resonance(SPR) sensor, was an optical sensor based on surface plasmon excitation. SPR sensors measured fluctuations of the electromagnetic field occurring at the surface of a metal film due to the changes of the refractive index of surrounding environment. SPR sensors had several advantages such as real-time measurement, short-response time and high sensitivity, which made it a popular sensing technique used in medical diagnostics, food safety and environmental monitoring.In this paper, we were mainly focus on the study of optical fiber SPR sensors prepared by wet-chemical coating. We developed three different kinds of silver-based optical fiber SPR sensor, and optimized the preparation conditions to enhance the sensitivity of the SPR sensors. Moreover, the sensor was further modified with antigen to act as a biosensor. The conclusions were drawn as follows:SPR optical fiber sensors based on silver mirror reaction: we developed a reflective SPR optical fiber sensor based on silver mirror reaction, and realized a quick surface biological functionalization on the silver nanofilm by dopamine self-polymerization for monitoring of antigen-antibody interaction. A homemade SPR instrument was applied to investigate the effect of sensing length and various modification on the SPR signals. The results showed the fabricated SPR optical fiber sensors had a high sensitivity. When the sensing length was 1.5 cm, the sensitivity based on wavelength shift was 4166 nm/RIU. In addition, the SPR optical fiber sensors were further used to monitor the process of the binding of IgG and IgG antibody, demonstrating the biological application of this biosensor.LSPR optical fiber biosensors based on silver nanoparticles: we developed a reflective localized surface plasmon resonance(LSPR) optical fiber sensor based on silver nanoparticles(Ag NPs). By used a scanning electron microscope(SEM), the surface morphology of the as-prepared LSPR sensor had been characterized. A homemade SPR instrument was applied to study the sensitivity and the stability of the sensor. After biological functionalized with human IgG, the LSPR biosensors could be used for monitoring of antigen-antibody interaction. The results showed that, most of the Ag NPs immobilized on the sensing surface had a uniform particle size, and were separated from each other. And the fabricated LSPR optical fiber sensors had a sensitivity of 400 nm/RIU with the refractive index between 1.33 to 1.40. The sensitivity was high, and the signal response time was short, which meant the LSPR sensor had a broad application prospect.LSPR optical fiber sensors based on PAD/Ag/PDA structure: we developed a reflective localized surface plasmon resonance(LSPR) optical fiber sensor based on the reduction property of dopamine, and fabricated a LSPR sensor based on PDA/Ag/PDA structure. By compared the sensitivity between the PDA/Ag-based sensor and the PDA/Ag/PDA-based sensor with different refractive index solutions, we could further evaluate the as-prepared sensor of a distinct sandwich constructure. The results showed that, the as-prepared sensor had a high sensitivity of 961 nm/RIU, and had a broad application prospect.