Study On Metamaterials Based Terahertz Sensor For Diagnosis Of Lung Cancer

Terahertz(THz)wave has excellent properties such as good security,strong penetration,and fingerprint identification of substances.Thus,it is widely applied in safety inspection,material identification and biomedicine.Metamaterials,also called artificial electromagnetic materials,have specific electromagnetic properties which are not possessed by the natural materials.The metamaterials based THz sensor is sensitive to changes in the surrounding dielectric environment and is a label-free affinity sensor.At present,the research of the metamaterials based THz sensor used in the biomedical field has become a research hotspot in THz and medicine domain.This dissertation focuses on the study of metamaterial based THz sensors and its application in the detection and diagnosis of early lung cancer.The main contents are as follows:At first,we study the theories of the metamaterials based THz sensors,including the basic theory,structural design method,sensing characteristics and performance index of the metamaterial based THz sensor.Secondly,we design two metamaterials THz sensors,i.e.,ohm-ring shape sensor and split ring shape sensor.The ohm-ring shape sensor have two resonant peaks,both of which are sensitive to the changes in the refractive index of the analytes,but are less sensitive to the changes of thickness.The split ring shape sensor has only one resonance peak and is not only sensitive to the changes in the refractive index,but also to the thickness change of the analytes.Third,study on the diagnosis of lung cancer is carried out by using the pre-processed ohm-ring shape metamaterials based THz dual-band sensor.In the experiment,the sensor surface is covered with a tissue sample and the cancer tissue and normal tissue can be identified by the frequency shift of the resonant peak of the sensor.The experimental results show that the cancer tissue shows a 31 GHz red-shift in low-frequency region,while the normal tissue produces only a 19 GHz red-shift.Moreover,the cancer tissue shows a 15 GHz red-shift in high frequency region,while that of the normal tissue is only 12 GHz.Therefore,the red-shift of the resonance frequencies of the sensor can be used to distinguish the cancer tissues and normal tissues.In this dissertation,the proposed method of using metamaterials THz sensor to diagnosis early lung cancer is rapid and simple,and can be used as a very useful supplement to the existing diagnosis technology.This method is also very important and useful for early detection and diagnosis of lung cancers and other cancers.