Design And Application Of Microwave Biosensor For Liquid Detection

In recent years,with the development of biotechnology and nanotechnology,biosensors have been widely researched and applied in the medical field.Using biosensors for glucose concentration and cell suspension detection has been a research hotspot for scientists.Microwave biosensors have low processing costs,fast detection speeds,small device sizes,and have broad application prospects in medical diagnosis.Nevertheless,improving the sensitivity and accuracy of biosensors is still a current research focus and an urgent problem to be solved.This thesis focuses on improving the sen-sitivity and accuracy of biosensors and explores the research on microwave biosensors that can be used for liquid detection.The main work and contributions are as follows:（1）A biosensor with multiple transmission zeros was proposed based on theoretical analysis of the source-load coupling structure to solve the problem of low precision of traditional biosensors.This biosensor can be used for glucose concentration and cell suspension detection.Simulation was used to detect different concentrations of glucose,and the simulation results showed that the sensor can accurately detect glucose concentrations.Measurement was used to detect Hep G2 in cell suspen-sion,and the results showed that the sensor had multiple transmission zeros that can be used for detection.（2）A wideband biosensor was proposed based on the theoretical analysis of the end-coupled structure to solve the problem of narrow detection bandwidth of traditional resonator biosensors.This biosensor provides an 8GHz detection bandwidth,which can detect the high sensitivity frequency band of the test substance that is lost due to the narrow detection bandwidth of the sensor.The simu-lation of different concentrations of glucose showed that the sensitivity of the sensor to glucose con-centration was much higher than that of the biosensor with multiple zeros proposed in this thesis.The measurements of cell suspension showed that the sensor also had high detection sensitivity to Hep G2.When Hep G2 were present in the cell suspension,the sensor’s detection frequency deviation was obvious,up to 1.2GHz.（3）An inductively diaphragm-coupled waveguide biosensor was designed to improve the detec-tion sensitivity of the glucose concentration and cell suspensions.A liquid detection method based on the waveguide biosensor was proposed.By inserting the glass needle containing the liquid to be measured into the slot reserved by the waveguide sensor as the perturbation,the glucose concentration can be measured according to the S₂₁ parameter curve obtained by the sensor.The differentiation factor D was defined to measure the influence of the liquid to be measured on the parameters of the waveguide sensor S₂₁.Combined with the four differentiation factor D curves obtained from the four slot holes of the sensor,the types of cancer cells in the suspension could be effectively detected.The experimental results show that the method can be used to detect glucose concentration and distinguish A549,Hep G2,SW480 and Caki in cell suspension.