Research On The Sensing Applications Of Surface Plasmon Resonance And Polymer Optical Fiber

The research work in this dissertation is supported by the National Key Basic Research Program of China(No.2006CB302905),the Key Program of National Natural Science Foundation of China(No.60736037) and the National Natural Science Foundation of China(No.10704070).The main work includes the researches on the applications of Surface Plasmon Resonance(SPR) sensing technique as well as Polymer Optical Fiber(POF).Surface Plasmon resonance sensors have been widely used in the studies of biomolecular interaction analysis and concentration measurement,due to their advantages in high sensitivity,label-free,non-destructive and real-time detection,etc. With further and deeper study in this field,surface plasmon resonance technology will certainly be applied in various areas,ranging from health-care,pharmaceuticals, environmental monitoring,and food safety to homeland security.But practically,there are still some limitations for the further development of SPR sensor,such as high cost of the chip,being unable to detect low concentrations of small molecules or large-sized cells,as well as not possible to be carded out with real-time and remote monitoring in the outdoor applications,etc.In this thesis,I analyzed the influences of the parameters of all SPR sensor components,and by optimization,I have made it possible to choose parameters to the best sensing performance.A piece of bimetallic chip combing gold and silver film is designed and fabricated,and then successfully utilized in the commercial SPR instrument.Also a fiber SPR sensor with flexibility and high-sensitivity is developed.The photosensitivity of polymer optical fiber performs is studied,and birefringence fiber grating is written in POF with double frequency grating method. The possibility of combining the birefringence grating and SPR technique is discussed. The sensing performances under the influences of temperature,stress,and strain by using POF grating are theoretically analyzed.A velocimetry system based on Polymer optical fiber and the VCSEL self-mixing effect is built up,and the influences of POF on self-mixing signals are discussed.The main research work and conclusions in this thesis are as following:1.Based on the Krestchmann SPR structure,I study how to choose the parameters of the SPR sensor's components in designing the sensor in order to achieve the best sensing performance.A wavelength modulation SPR sensor with POF is proposed.2.A bimetallic chip combing gold and silver film is designed,and the optimum thickness ratio of silver and gold is studied according to transfer matrix method. We fabricated the bimetallic chip,and applied it into the BIAcore3000 SPR instrument for researching the interactions between sulfamethoxazole and its antibody.The dispersion relationships,loss properties and field distribution of long-range surface plasmons(SPs) are discussed according to the waveguide theory.3.The birefringence process and reservation characteristic of azo doped POF is studied to guide the selection of core material in the POF grating.Birefringence fiber grating is written in POF with double frequency grating method,and the possibility of the birefringence grating applied in SPR Sensors is discussed.The polymer fiber gratings for sensing temperature,stress and strain is theoretically simulated.4.A simple and flexible velocimetry system based on POF and VCSEL self-mixing effect is established.The flow measurement inside the liquid at the range of 38-193mm/s is obtained,and the measurement error is less than 1%.The influences of POF on self-mixing signals are discussed,and the mixed-signal waveform distortion and spectrum broadening phenomenon is observed for the first time.Highlights of the dissertation are as following:1.A bimetallic chip of gold and silver is designed,and it has been successfully applied in the commercial BIAcore3000 instrument to study the interaction in biological molecules.Compared to the traditional single-layer gold film chip,this new type of sensor chip shows narrower resonance peak,higher sensitivity and still maintains the stability of single gold-film chips.2.Optical fiber SPR sensor with a dielectric protective film is developed,and its optimized parameters are discussed.The sensitivity of sensor at the refractive index of n=1.3945 is 4778nm/RIU.And a dual-channel fiber SPR sensor for measuring the gases and liquids is designed with the help of a dielectric layer.3.For us,it is the first time to report the birefringence effect in copolymer optical fiber.Residual birefringence of 72%is obtained in the material under low azo concentration.Many factors,causing the influences,such as azo concentration, spacer and pump optical power to the birefringence characteristics,are analyzed. Birefringence fiber grating is written in POF in double frequency grating method. Separate polarized peak is analyzed theoretically,which shows that the birefringence grating has great potential in the application of fiber SPR sensors.4.We build up the velocimetry system based on POF and VCSEL self-mixing effect for the first time.It is simple and easy to adjust the structure of our system.The real-time and rapid flow measurement could be carried out by using data acquisition card as well as Labview software instead of the expensive and bulky spectrum analysis instrument.Due to the fact that it has the advantages in flexibility,ease of handling,and perfect biocompatibility,the polymer fiber could be used as the disposable probe for measurement of blood flow velocity in vivo.