Research On Liquid Sensor Based On Electromagnetic Metamaterials

Traditional sensors have the disadvantages of large volume,low sensitivity and contamination of samples.Using the unconventional characteristics of metamaterial,the limitations of original materials can be overcome.Compared with traditional sensors,metamaterial sensors have the advantages of simple design,high sensitivity,strong selectivity and instant detection.Based on the spilt ring resonator(SRR)and complementary spilt ring resonator(CSRR),two kinds of metamaterial sensors are designed and studied.By comparing the two kinds of sensors,metamaterial can provide new ideas and methods for the design and performance improvement of sensors.The main work of this paper is summarized as follows:(1)A binary mixture concentration metamaterial sensor based on four hexagonal spilt ring complementary resonators is proposed.By optimizing the structure size of the sensor,the sensitivity of the sensor is improved.The microchannel made of silica glass material can not only avoid environmental pollution,but also only micro-liter-nano-liter samples are needed for detection.The requirement of a small number of samples and low working frequency make the sensor suitable for various applications.Introducing the measured liquid into the glass tube of the resonator and the center hole of the transmission line,it can be concluded that the sensitivity of the sensor to different concentrations of binary liquids:methanol-water,ethanol-water and methanol-water was 19.7MHz/10%,26.1MHz/10%and 7.5MHz/10%,respectively,when the working frequency was 2-3GHz.In the process of sample measurement,two Sub-Miniature-A(SMA)microwave connectors and a suitable sample holder are used,and the experimental research is realized by PNA-L Agilent Vector Network Analyzer(VNA),and its working frequency ranges from 0.5 GHz to 3.5 GHz.Comparing the simulation results with the measured results,the trend consistency can be achieved.(2)A deformed SRR structure with square split ring and rhombic ring is proposed,and a sensor for non-invasive detecting blood glucose concentration is designed.The model is simulated and optimized by using microwave studio simulation software(CST)based on finite integral technology,the Q value can reach 25,so that the sensor can quickly analyze the dielectric properties of liquid samples at microwave frequency.In addition,based on the dielectric characteristics of blood glucose samples measured by coaxial dielectric probe kit,the corresponding numerical model is established and imported into the simulation software,and then the blood glucose concentration is detected by the sensor.By utilizing ADS circuit simulation software,the equivalent circuit of the sensor is fitted,and the impedance matching,structural parameters and sensing mechanism of the sensor are further analyzed in combination with the equivalent circuit,electric field and surface current distribution.Narrow band and high Q are very important for blood glucose detection using RF resonator.Compared with traditional blood glucose detector,non-invasive design makes blood glucose detection easier and more sensitive.The two sensors designed in this paper have the advantages of high sensitivity,simple structure and fast response speed,which can be a powerful choice for future industrial applications.