Research On Electromagnetic Characteristics And Sensing Applications Of Artificially Planar Metamaterials

With the advancement of the “Made in China 2025” strategy and the development of Internet of Things applications,sensing technology has received unprecedented attention and ushered in an once-in-a-lifetime development opportunity.New biological,gas and optical intelligent sensing based on micro-nano processing technology is the focus of current sensing technology research.Metamaterials are a class of artificial materials with extraordinary physical properties not found in natural materials.Metamaterial-based sensing technology has the advantages of miniaturization,high sensitivity,simple structure,and high flexibility.In addition,it shows broad application prospects,which is in line with the current development trend of sensing technology.The dissertation addresses the needs of “made in China 2025” and the Internet of Things for new types of biological,gas,and optical intelligent sensing.In the microwave,terahertz,and infrared bands,the dissertation conducts research on the application of metamaterial sensing technology in the fields of biology,gas,and optics.Starting from Maxwell's equations,the dissertation discusses the theoretical basis of metamaterials in electromagnetic fields,and establishes the equivalent circuit model of lumped components and the Time-domain coupled-mode.Metamaterial test strips,double-layer complementary terahertz biosensors and infrared metamaterial multi-gas composite sensors are developed;The micro-morphology of the developed metamaterial sensor is characterized;the test platform of the metamaterial sensor is established;the performance of the metamaterial sensor on biological and gas sensing is analyzed;the test results and influencing factors of metamaterial sensors are systematically analyzed;the sensing advantages of metamaterial sensors compared to other types of sensors are discussed.The main work and conclusion of the dissertation are summarized as follows:(1)Starting from Maxwell's equations,the theoretical basis of metamaterials in electromagnetic fields is described,the electromagnetic resonance characteristics involved in the application of metamaterial sensing are discussed,the influence of electromagnetic excitation methods on the resonance characteristics of metamaterials is studied,and lumped elements Equivalent circuit model and time-domain coupled-mode model are established.The results show that the lumped element equivalent circuit model is suitable for the analysis of metamaterial sensors in the microwave and terahertz bands,and the time-domain coupled mode model is suitable for the analysis of metamaterial sensors in the infrared optical band.(2)Sensing applications of metamaterials in the microwave field are studied,and metamaterial test papers are prepared using shadow mask type deposition technology and wax spray printing technology.Metamaterial test strips can detect target molecules by using the target molecules captured by the resonator induction immunochromatography module.The results show that the detection limit and sensitivity of the metamaterial test strips reach 0.784 ng/m L and 10.214 MHz(ng/m L),respectively.Among them,the detection limit is 63 times(50 ng / m L)higher than that of colloidal gold test strips judged with the naked eye.The stability is 18 times higher than that of the fluorescent test paper labeled with fluorescein.In addition,metamaterial test strips avoid interferences such as self-absorption,specular reflection,and long-term signal quenching in optical methods.(3)The sensing applications of metamaterials in the field of terahertz are studied,and a double-layer complementary terahertz biosensor is prepared using photolithography and electron beam evaporation processes.The results show that the double-layer complementary structure can improve the sensitivity of the sensor,and the sensitivity of the complementary sensor is 7 to 18 times higher than that of the convex sensor and the concave sensor.Meanwhile,the sensor exhibits strong polarization insensitivity and can maintain a high resonance state over a wide range of incidence angles above ± 50°.In addition,the complementary biosensor has the ability to monitor the state of streptavidin and biotin binding,and the sensitivity of detecting biotin reaches 153 GHz/?M.(4)The sensing applications of metamaterials in the field of infrared optics are studied.The infrared metamaterial multi-gas composite sensor is fabricated using step scanning lithography and ion beam etching.The infrared metamaterial multi-gas composite sensor uses the surface enhanced infrared absorption effect and ZIF-8 film to achieve higher performance gas detection capabilities.The results show that the infrared metamaterial multi-gas composite sensor can simultaneously sense on-chip CO2 and CH4,with short response time(<1 minute),high accuracy(maximum error:CO2: 1.1%,CH4: 0.4%),detection limit High(CO2: 80 ppm,CH4: 230 ppm)and excellent linearity over a wide concentration range(0 ppm to 2.5 × 104 ppm).The presented method is flexible and can expand the amount of gas by designing more resonances and developing a suitable MOF.