Study On Metamaterials Based Terahertz Sensor And Its Application Application For Biomedical Detection

The photon energy of a terahertz(THz)wave is only one millionth of that of the x-ray,which is basically no harm to the constructure of the biology molecule.Metamaterials are artificially composited electromagnetic materials or structures which have special physical properties not found in natural materials.The advent of metamaterials has provided new ideas for the development of terahertz devices.Tera-based sensors based on metamaterials have brought hope to the application of terahertz technology in biomedical applications.The metamaterial THz biosensor is a label-free affinity sensor which is particularly sensitive to changes of the dielectric environment on the sensor surface and can therefore be used for the detection of protein molecules,human tissues and drug reaction processes.In this paper,the metamaterial terahertz biosensor is used to analyze the concentration of bovine serum albumin,the differentiation between cervical cancer tissue and normal tissue,and the detection process of liver cancer cells and anticancer drugs.The details are as follows:1.We study the related theories,fabrication techniques,design methods and performance indicators of the metamaterial THz biosensor.A metamaterial THz biosensor based on four resonators and an "E"-shaped metamaterial THz biosensor are designed and their sensing performances are analyzed.2.We designed and fabricated a supermaterial terahertz sensor with four resonators of the same frequency,and high sensitivity is achieved by exciting four synchronous LC oscillations in a unit cell.The effect of geometries on the resonance frequency of the sensor is investigated using finite integration technology(FIT),and the simulated sensitivity is 85 GHz per refractive index unit(RIU).The biosensor sample is fabricated using a surface micromachining process and characterized by a THz time domain spectroscopy(TDS)system combined with bovine serum albumin(BSA)solution as analyte.The experimental results indicate that the resonance frequency shows distinct redshift when increases the concentration of BSA solution.When the concentration is high up to 765 ?mol/L,the frequency shift reaches 50 GHz,and the measurable minimum concentration is low to 1.5 ?mol/L.The biosensor is small in shape,wide in measurable range,convenient in operation and rapid in detection,which are of great significance for rapid concentration measurement,biomolecules detection and disease diagnosis.3.We designed and produced an "E" shaped metamaterial terahertz biosensor.we study the sensing characteristics of the sensor,its sensitivity is up to 74 GHz / RIU,and isnot sensitive to a small range of angular deflection.We used the sensor to distinguish between cervical cancerous tissue and normal tissue in the corresponding area.Firstly,the THz time-domain spectroscopy system is used to detect the cancerous tissue and normal tissue of multiple samples,and the corresponding refractive index and absorption coefficient are calculated.It can be seen from the comparison that the refractive index can not distinguish between the two tissues,and the absorption coefficient is Can be distinguished.But the accuracy is not guaranteed.Therefore,this paper proposes the use of metamaterial THz biosensors to distinguish between cancerous and normal tissues.In the experiment,the sample is covered on the surface of the sensor for testing.The experimental results show that the frequency shift of the sensor resonance peak covering the normal tissue is smaller than the frequency shift of the sensor resonance peak covering the cancerous tissue.Therefore,we can distinguish between cancerous tissue and normal tissue according to the frequency shift of the sensor resonance peak.The detection method is convenient,fast,high in accuracy,simple in operation.It has certain reference significance for diagnosis of other cancers.4.The metamaterial THz biosensors are used to detect the reaction process of liver cancer cells and anticancer drugs.Two kinds of liver cancer cells and one normal liver cell are selected to react with two anticancer drugs.The reaction of the cell resonance with the change of the frequency shift of the sensor resonance peak and the effect of drug concentration on the reaction process are determined.The results show that the use of metamaterial THz biosensors for cell-drug reaction process detection is feasible.And this result is very meaningful for the study of the amount and efficacy of anticancer drugs.