Research On Glucose And Cholesterol Sensing Technology Based On Fiber Optic SPR Sensor

Glucose and cholesterol concentrations are two important biochemical indicators in human blood,which affect human health,and are also the most concerned by medical personnel.Therefore,it is very important to measure the concentration of glucose and cholesterol.The traditional detection methods of glucose and cholesterol concentration are mostly based on the combination of physical and chemical methods,which have many limitations and can not meet the requirements of modern detection,and are gradually eliminated by society.Optical fiber sensor has the characteristics of high sensitivity,rapid response,anti electromagnetic interference and so on,which has a wide application prospect.The surface plasmon resonance(SPR)sensor is a kind of optical fiber sensor with high application prospect.This kind of sensor not only has high sensitivity,but also has a variety of structures,which attracts the attention of researchers.In this paper,focusing on the structural characteristics of fiber-optic SPR sensor,the sensing characteristics of reflective fiber-optic SPR sensor are mainly studied,and it is combined with different biosensor membranes to realize the measurement of biomass such as glucose and cholesterol.The main research work includes the following aspects:(1)The traditional Kretschmann three-layer dielectric structure is used to analyze the theory of SPR sensor,and Comsol software is used to simulate and analyze the characteristics of optical fiber SPR sensor.The effects of three parameters on the sensor performance,including the type of metal film,the thickness of metal film and the sensing length of sensor,are simulated.The simulation results show that when the thickness of metal film is 40nm-50nm and the sensing length is 10-20mm,the performance of SPR sensor is the best.The refractive index sensitivity of optical fiber SPR sensor based on silver film reaches 2962.8nm/RIU,and the refractive index sensitivity of optical fiber SPR sensor based on gold film reaches 2108nm/RIU.Through the simulation and comparative analysis of the main parameters of optical fiber SPR sensor,it provides a certain theoretical basis for the follow-up experimental research.(2)The combination mode of glucose oxidase(GOD)and cholesterol(Chox)with the metal surface of optical fiber SPR sensor was designed and optimized.A complete glucose and cholesterol detection system was built,and the performance of fiber-optic SPR biosensor was tested.In the experiment,a reflective fiber optic SPR sensor was prepared by using a 600 μm diameter optical fiber(HPCF-600/630-750-37).Then,the immobilization process of glucose oxidase was optimized,and the optimal coating parameters were obtained.The results showed that the optimal concentration of glucose oxidase was 15mg/ml,and the optimal fixation time was 10 hours.The sensitivity of glucose is 85.4nm/(mg/ml).Compared with the traditional method,the sensitivity of glucose is greatly improved,and it has better selectivity and stability.(3)Based on the reflective optical fiber SPR sensor and cholesterol oxidase,a complete cholesterol measurement system is built.The experimental results show that the sensitivity of cholesterol measurement can reach 85.7nm/μM.On this basis,a fiber optic SPR cholesterol sensor based on cyclodextrin was proposed for the first time.By optimizing the fixation process of the cyclodextrin sensitive membrane,the sensitivity of cholesterol measurement was increased to 156.18nm/μM.In this paper,the optical fiber SPR sensor for glucose and cholesterol concentration measurement is studied theoretically and experimentally.The preparation process of the sensor was optimized to realize the high sensitivity measurement of glucose and cholesterol concentration.At the same time,in cholesterol measurement,the non enzyme sensitive membrane cyclodextrin was proposed as the sensitive membrane,which enriched the diversity of SPR fiber sensor in biomass measurement,and reduced the production cost of the sensor,which further promoted the development of optical fiber sensing technology in biomedicine.