Biochemical Detection Based On U-shaped Optical Fiber SPR Senso

By bending the straight optical fiber into a U-shaped,the optical coupling in the fiber core can be realized to the cladding.The sensing metal film can be directly coated on the outside of the U-shaped structure cladding to form a U-shaped optical fiber surface plasmon resonance(SPR)sensor.Because of the existence of U-shaped structure,the SPR incidence angle in the sensing area is easy to control and change,and the sensitivity of the sensor will be improved.Compared with the straight optical fiber SPR sensor,the sensitivity of the Ushaped optical fiber SPR sensor will be increased by about 40%,which can accurately detect low concentrations of biochemical analytes,which makes the U-shaped optical fiber SPR sensor more suitable for biochemical detection.In this paper,a U-shaped optical fiber SPR for biochemical detection is proposed.Based on the in-depth study of the performance of the U-shaped optical fiber SPR sensor,a U-shaped optical fiber SPR sensor with excellent performance is designed and manufactured.Nano-materials are utilized to sensitize it to further improve its sensitivity,and then the sensitized sensor is applied to the detection of actual analytes to be tested.Specific work includes:1.Research on sensing performance of U-shaped optical fiber SPR sensor.An experimental test platform for the sensing performance of U-shaped optical fiber SPR sensor was built.The parameters affecting the performance of U-shaped optical fiber SPR sensor were studied in detail through the control variable method.The best design parameters were obtained as follows: graded index multimode fiber as the sensing fiber,the U-shaped optical fiber with a bending radius of 0.5-1 mm,and the sensing metal film of 50 nm.On this basis,a dual-channel optical fiber SPR sensor based on U-shaped structure is proposed.By controlling the bending radius of two U-shaped optical fibers,the resonant wavelength working range of the two channels is controlled to completely separate the working wavelengths of the two channels.When the refractive index range is 1.333-1.385,the refractive index sensitivity of the two channels is 1414 nm/RIU and 3687 nm/RIU respectively.2.Study on the modification and sensitization of the sensing film of U-shaped optical fiber SPR sensor.The properties and modification methods of gold nanorods,metal-organic frame materials and MXenes materials were studied in detail.These three materials were successfully modified on the surface of U-shaped optical fiber SPR sensor by different modification methods.Comparing the performance of the sensor before and after the modification,it can be found that the nano-materials can adjust the resonant wavelength range of the U-shaped optical fiber SPR sensor to a certain extent,and improve the sensitivity of the sensor to a certain extent,and the maximum refractive index sensitivity of the sensor can be increased by 30%.3.Research on the application of U-shaped optical fiber SPR biosensor in biochemical detection.The U-shaped optical fiber SPR sensor designed and made in this paper and sensitized by nano-materials is applied to the detection of heavy metal lead ions,tumor marker MUC1 protein,glucose and sucrose,respectively.For different analytes to be tested,the detection method and nano-materials shall be reasonably selected to realize their detection.According to the test results,the minimum detection limit for heavy metal lead ions is 0.34 ng/mL,and the minimum detection limit for tumor marker MUC1 protein is 0.16pg/mL.Which indicates that the proposed U-shaped optical fiber SPR has excellent performance,high detection sensitivity,good specificity,stability,has a lower detection limit for these substances to be tested,and can realize the detection of low concentration biochemical analytes.