Sensing Mechanism Of Oil And Amino Acid By Surface Plasmon Resonance Technology

Surface plasmon resonance is the resonance between incident photons and free electrons on the metal surface.It has the characteristics of local field enhancement effect and breakthrough of the optical diffraction limit.It has important research value in optical devices.The current detection technologies for oils and amino acids have many shortcomings,such as cumbersome process,long detection period,and sensitivity to be improved.The optimization and improvement of detection technology is indispensable for food quality supervision and innovation,and also plays a very important role in protecting people's health.This dissertation is based on surface plasmon resonance technology,starting from Fano-type resonance and graphene sensing.The optical transmission properties of the micro-nano structure and its sensing mechanism in oils and amino acids were studied in order to obtain better sensing performance and optimize sensing detection.The main contents of this dissertation are as follows:Edible oil is one of the important sources of production for human survival and development,and the oil industry also occupies an important part in the national economy.The Fano-type resonance sensing structure composed of silica substrate and silver metal layer was studied,and the sensing mechanism was analyzed in combination with edible oil.Firstly,the surface plasmon is excited in the semi-ring straight waveguide,coupled into the U-shaped resonator during propagation,and finally forms an obvious antisymmetric Fano peak in the transmission spectrum.The influence of the geometrical parameters of the structure on the transmission spectrum was investigated by the numerical analysis software.The transmission sensitivity of 825 nm/RIU was obtained by using the high sensitivity of the Fano resonance curve,which was superior to the reported similar sensing structures.The research on the sensing mechanism of edible oil shows that the sensing structure can detect the listed pure edible vegetable oils.The sensing structure with high sensitivity and nondestructive detection in this chapter provides a promising idea for further research on oil sensors.There are many kinds of food additives,and amino acids are an important part of them,but excessive or inappropriate addition will cause harm to food safety.A sensor composed of graphene and gold as the component unit main structure was studied,and the other parts included a cap layer,a depleting layer of silicon dioxide,a reflector layer of gold and a buffer layer of silicon.Incident light excites surface plasmons on the graphene surface,improving the localization ability.It can be concluded that the absorption rates of the generated two modes reach 99.86% and 99.99%,respectively.The sensitivity is also as high as 1.1THz/RIU(9846 nm/RIU)and 1.5 THz/RIU(6962 nm/RIU)by numerical analysis software.There are big advantages in similar sensors.Further research shows that the sensor can maintain more than 95% absorption rate under transverse magnetic wave or transverse electric wave within 40°,and has a certain degree of insensitivity to polarization and incident angle.At the same time,the existence of graphene makes the structure have dynamically tunable.Different from the traditional direct analysis of the content of amino acids,the experiment chose the method of indirect analysis of amino acid aqueous solution to study the sensing mechanism of amino acids,which achieved trace and non-destructive detection to a large extent.The proposed graphene tunable sensor provides an important reference for amino acid sensing detection.