Study On Sensitivity Enhancement And Biochemical Detection Of Fiber SPR Sensor

Compared with prism SPR sensor,fiber SPR sensor has the advantages of small size,good real-time performance,remote sensing measurement and convenient placement in a narrow space.Therefore,it has a wide range of applications in the fields of medicine,biology,chemical monitoring,food safety inspection,mechanical structure monitoring and so on.However,because its sensing substrate is fiber,the SPR incident angle is difficult to control,the sensitivity of ordinary fiber SPR sensor is much lower than that of prism SPR sensor.The sensing sensitivity of fiber SPR sensor is affected by the sensing substrate,sensing film,total reflection angle and the environment to be measured,and its sensing sensitivity directly affects the application effect of biochemical sensing.Therefore,in this dissertation,the sensitization of core type fiber SPR sensor,cladding type fiber SPR sensor and additional modulation layer fiber SPR sensor were studied based on the sensing structure of the fiber SPR sensor.And by selecting the appropriate fiber SPR sensor,the biochemical sensing was realized and tested,specific work is as follows:1.Study on sensitivity enhancement of core type fiber SPR sensorBy employing the hollow capillary fiber filled with UV curing adhesive which has a wide range of refractive index,the special fiber with relatively controllable core refractive index was fabricated.And by employing corrosion and coating technology,the core type fiber SPR sensor was realized using the special fiber.By selecting the refractive index of the core,the sensitivity enhancement of the core type fiber SPR sensor and the detection of high refractive index solution can be realized.The testing results indicate that when the core refractive index decreases,the sensitivity is significantly improved,which can be increased to 3233.93nm/RIU.And when the core refractive index increases,the dynamic range of the sensor blueshifts,the same detection band can accommodate more resonance curves,which can realize the detection of high refractive index solution.2.Study on sensitivity enhancement of cladding type fiber SPR sensorUsing fiber microspheres to couple the light transmitted in the fiber core to the fiber cladding,and directly coating the sensing gold film on the outside of the cladding behind the fiber microspheres to form a cladding type fiber SPR sensor.By studying the influence of fiber microsphere parameters on the sensing performance of cladding type fiber SPR sensor,the sensitivity enhancement effect can be realized,and its sensitivity can be increased to 3637.06 nm/RIU.3.Study on sensitivity enhancement of additional modulation layer fiber SPR sensorThe metal nanoparticles were immobilized on the sensing gold film as the modulation layer,the electric field of the sensing gold film was enhanced owing to local surface plasma(LSPR)characteristics of the metal nanoparticles,so as to realize the sensitization effect of fiber SPR sensor.The graphene like 2D material Ti3C2-Mxene was placed inside and outside the sensing gold film respectively to strengthen the sensing gold film and enhance the sensitivity.Due to the rich functional groups on the surface of Ti3C2-Mxene,the fiber SPR sensor was modified by gold nanoparticles and 2D materials to further improve the sensing sensitivity of the fiber SPR sensor.Its refractive index sensing sensitivity can be increased to 5071.14nm/RIU,which is about 2.5 times that of the pure gold film sensor.4.Application of fiber SPR sensor in biochemical sensingThe performance comparison and stability testing of proposed sensor were conducted.Finally,the fiber microsphere SPR sensor was selected for the detection of heavy metal ions.Through the specific modification of mercaptan,the fiber microsphere SPR sensor can be used for the specific detection of mercury ion,and its limit of detection(LOD)can reach 20.75 p M.Because gold nanoparticles contribute to the binding of biological protein antibodies,the fiber SPR sensor modified by gold nanoparticles and Ti3C2-Mxene was selected for the detection of growth differentiation factor(GDF11).The fiber SPR sensor was functionalized successively by staphylococcal protein and GDF11 antibody.The lowest detectable concentration of GDF11 solution was 0.202pg/L.