Research And Design On The Metamaterials Sensor Based On SRR Resonators

In the field of science and technology,such as industrial,agricultural production and daily life,sensors are playing a significantly important role.There are three main requirements in a sensor design.Primarily,the sensor needs sufficiently high-sensitivity for the alterations of status of the object and conditions.Next,the sensor needs to have compact size and retain the shape of the objects unchanged,ease of installation.At last,the sensor should have a strong immunity to interference in different environments.Nowadays,metamaterial-inspired microwave sensors are attracting great attention because metamaterials are able to create some exotic electromagnetic properties.People have studied various types of sensors based on metamaterials,such as metamaterial-based microwave micro fluidic sensor,biosensing,refractive index sensor,metamaterial-inspired strain sensing,dielectric sensor.The major works of this dissertation are as follows:(1)we proposed a novel double-deck displacement sensor with a high linearity based on tunable horn-shaped resonators.The designed sensor included two substrate layers etched with copper metallization in various shapes.When the upper trip-type resonator layer has a relative displacement to the bottom horn-shaped resonator layer,the resonance frequency of the sensor is redshift.High sensitivity of the sensor is around 207.2MHz/mm with 4mm linear dynamic range.We fabricate the sample of the proposed displacement sensor,in addition the simulated results are verified by experiment.The proposed displacement sensor is appropriate for using MEMS technology in further miniaturization.(2)A low-loss and high transmission electromagnetically induced transparency like(EIT-like)structure is experimentally and numerically demonstrated in this paper.The proposed planar structure based on EIT-like metamaterial consists of two separate split-ring resonators(SRRs),and its resulting transmission level can maximally reach 0.89 with significant suppression of radiation loss.According to the effective medium theory(EMT),the imaginary parts of the effective permittivity and permeability of the metamaterial are used as the evidence of low-loss.In the analysis,the simulated surface current,magnetic field distribution and coupled oscillator model reveal the principle of high transmittance EIT-effect.Furthermore,the peak of transparency frequency is highly sensitive to the variation of refractive index in the background medium.The sensor based on the proposed EIT structure can achieve a sensitivity of 1.69 GHz/RIU(refractive index unit)and a figure of merit(FOM)of 11.66.Its high linearity and high sensitivity are also discussed through equivalent circuit theory.Such metamaterials have potential perspectives in sensing and chiral slow light devices.