Study On The Metasurface Based Terahertz Sensors And Their Application In The Biomedicine

The photon energy of terahertz(THz)wave is much smaller than that of the X-ray,and it cannot produce ionizing radiation and is safe for human body.Therefore,the application of THz technology in the field of biomedicine has become a hot research topic.It has become a major obstacle of the THz technology in the field of biomedicine that the water absorption of THz waves about the biological tissue is very strong and results in the attenuation of THz wave very seriously.The emergence of artificial electromagnetic materials(metamaterials),especially the appearance of metasurface,played an important role for accelerating the application of THz technology in the biomedical area.The metasurface is very sensitive to the change of dielectric environment on the surface,therefore,it can be used as a high sensitive THz sensor to monitor the changes of biological tissue.The main contents of this research are the response characteristics and the application of the metasurface based THz sensor in the biomedical area.The specific contents are as follows:1.We studied the theory,designing methods,fabrication and the sensing performance of the THz sensor based on the metasurface.In this section,We designed two kinds of sensors,and one is a ohmic ring structure and the other is a composite structure which is composed of a split ring and a bar.The samples were fabricated by the surface micromachining process.2.We studied the real-timely monitoring the interaction between protein and drugs in aqueous solution with THz metasurface biosensor.At first,four drug solutions,i.e.,roxithromycin,cefradine,norfloxacin and ciprofloxacin,were selected to react with bovine serum albumin solution,respectively.Then a small amount of reaction solution was dipped onto the surface of the metasurface biosensor,and the transmission spectra of the resonator at the different reaction time were measured by using the THz time-domain spectroscopy system.The frequency shift of the resonance peaks of the sensor changed with reaction process.The result shows that the metasurface THz biosensors can be used for monitoring the reaction process of protein and drug.Moreover,this result provides a new efficient detection method for the later research on the reaction of other proteins with drugs.3.We studied the method of testing the concentrations of the different antibiotic drugs in aqueous solution with THz metasurface biosensor.Three common antibioticsof ciprofloxacin,roxithromycin and norfloxacin were selected for the test experiment.The result showed that the frequency shift of the resonance peaks of the composite structure is proportional to the size of the antibiotic concentration.What's more,the sensitivity of the composite structure changed with different antibiotics.Therefore,the THz metasurface biosensor can test different concentrations of the antibiotic drugs.4.We studied the method of monitoring the interaction between anticancer drugs and nucleic acid in aqueous solution with THz metasurface biosensor.By studying the reaction process of colchicine and methotrexate with nucleic acid,we proved that it is feasible to monitor the reaction process of anticancer drugs and nucleic acid by using THz metasurface sensors.These research results are very important for the study of anti-cancer drugs in the research stage and their treatment effects.