Research On Metasurface Terahertz Sensor And Its Application For Substance Detection

Metasurfaces(MSs),as a kind of ultra-thin two-dimensional array plane,which is constructed artificially to overcome the limitations of difficult processing and high electromagnetic wave loss of metamaterials(MMs),has all the characteristics of metamaterials and can have physical properties that natural materials do not have.Biosensors based on the special response of metasurfaces structure to terahertz wave have become a hot spot in the field of biomedical detection.Metasurface terahertz sensors can detect proteins and biological reagents by "sensitively sensing" the changes of dielectric environment on the metasurfaces,and these sensors have excellent performance such as high efficiency,no label and good security.In this paper,the electromagnetic response characteristics and application for substance detection of the metasurface terahertz sensor are studied.The details are as follows:(1)The basic theory,simulation design,processing technology and process,sensing characteristics and performance index of the metasurface sensor are studied.(2)An ultra-high Q-value metasurface terahertz sensor based on double ellipse structure is designed by using the finite integral method,By optimizing the parameters of the sensor,the Q value of the sensor reaches 348,and it also has the ultra-high sensitivity of 293 GHz/RIU.Finally,the sensing mechanism is analyzed based on the theory of bound states in the continuum and electromagnetic field.(3)A metasurface terahertz sensor is designed and fabricated,which is composed of "smiling face" periodic cells.The sensitivity of high frequency and low frequency resonant peaks of the sensor reaches 108 GHz/RIU and 86 GHz/RIU.The sensor is used to detect the concentration of three kinds of cancer marker protein solution:human epidermal growth factor receptor-2(HER2),carcinoembryonic antigen protein(CEA)and alpha fetoprotein(AFP).The results showed that when the concentrations of HER2,CEA and AFP are increased from 0.1 ng/m L to 100 ng/m L,the corresponding resonance peaks of transmission spectrum shifts to low frequency,and shifts to 26 GHz,24 GHz and 23 GHz,respectively;and the detection of three protein concentrations by the sensor is 0.1 ng/m L.The experimental results also show that the sensor has good robustness and excellent linearity,and has important potential in the field of medical detection and disease diagnosis.(4)The nano gold/graphene/thionine(AuNPs/RGO/TH)layer is constructed on the metasurface composed of periodic units of "smiling face" structure to adsorb the aptamer HB5(APT-HB5)of HER2 protein.The aptamer HB5 is used to modify the surface of the sensor to detect HER2,CEA and AFP protein solution.The results show that when the concentration of HER2,CEA and AFP solution increases from 0.1ng/ml to 100 ng/ml,the resonant peaks of the corresponding transmission spectra shift to low frequencies by 38 GHz,29 GHz and 27 GHz,respectively.Compared with the unmodified sensor,the aptamer modified sensor not only improves the sensitivity,but also has specific detection ability for aptamer antigen.These detection methods proposed in this paper open up new ideas for the application of terahertz sensing technology in biomedical field.