Research On Prism-type Bimetallic Surface Plasmon Resonance Sensor

Surface plasmon resonance（SPR）sensor is widely used in many key fields such as food safety analysis,medical diagnosis,and environment pollution detection,owing to its characteristics of quick response,no-destructiveness detection,and free labeling.However,the current SPR sensor still has the problem of low sensitivity,which limits its application.Studies have shown that the introduction of two-dimensional nanomaterials,silicon,titanium dioxide,and other sensing materials can effectively enhance the sensitivity of the SPR sensor.In recent years,research on the SPR sensor performance based on the above single material or material combination has become a research hotspot.We summarized the results of previous studies and found that although the introduction of new materials can effectively improve the sensitivity,the increased interface effect leads to the widening of the reflection spectrum,resulting in a decline in detection accuracy.To address these problems,firstly,the thesis proposes and studies the SPR sensor structure based on Ti O₂-Si O₂composite layer,copper-platinum bimetal and black phosphorus,and brings out the problem of decreased detection accuracy synchronously.Then,the Fabry-Pérot（F-P）cavity structure is introduced to solve the problem of low detection accuracy.Finally,based on different sensing materials,the research and application prospects of F-P cavity in improving the detection accuracy are compared and analyzed.The specific research contents and results are as follows:（1）To solve the problem of the low sensitivity of the SPR sensor,we proposed an SPR sensor structure based on Ti O₂-Si O₂composite layer,copper-platinum bimetal and black phosphorus.By optimizing the thickness of each film layer,the sensitivity of the sensor reaches 533°/RIU,3.9 times that of the single copper structure,and the detection limit is as low as 2×10^-7RIU,two orders of magnitude higher than that of the single copper structure.Although the sensitivity increased by 3.6 times due to the introduction of platinum layer,the detection accuracy decreased by 91.4%.（2）To solve the problem of reduced detection accuracy caused by the introduction of new materials,we proposed a structure of F-P cavity SPR sensor.Specifically,we used Ba Ti O₃,a perovskite material with high refractive index and low loss,to wrap copper（Cu）-nickel（Ni）bimetal and form an F-P cavity for narrowing the reflection spectrum,thereby improving the detection accuracy,and polymethyl methacrylate（PMMA）was used as the sensing medium layer to improve the stability of the sensor chip.The results showed that compared with Cu/Ni/PMMA structure,introducing the F-P cavity increased detection accuracy by 15.4%and sensitivity by 6.2%.（3）With respect to the question of whether the F-P cavity holds promising research and application prospects in improving detection accuracy,we first studied the influence of the double Ba Ti O₃layer F-P cavity on the performance parameters of the Ti O₂/Si O₂/Cu/Pt/BP structure.Secondly,we further compared and analyzed the influence of the F-P cavity on sensing performance parameters from three aspects:plasma metal materials,F-P cavity materials and sensing medium layer materials.The results show that the average detection accuracy was improved by 8.2%.In addition,when the F-P cavity was introduced on one side,the detection accuracy was reduced,while after introducing the other side to form a complete F-P cavity,the detection accuracy was improved to different degrees,indicating that the improvement in detection accuracy was not based on the characteristics of the sensing material but on the effect of the F-P cavity.These results fully demonstrate that the F-P cavity has broad research and application prospects in improving detection accuracy.This thesis provides a new method to improve the sensitivity and detection accuracy of SPR sensor,as well as a theoretical basis for the application of F-P cavity in the structure design of SPR sensor.