Research On The Detection Of Multiple Brain Functional Regions Using Microwave

The use of microwave technology to probe different functional regions of the brain has contributed to a deeper understanding of the brain’s mechanisms.The principle of microwave detection of brain neural activity is that according to the changes of electrical parameters of brain activity state,electromagnetic wave is emitted by antenna to detect the changes of electrical parameters,to analyze the state of brain activity.Therefore,this paper mainly studies antenna design,brain neural activity detection simulation and simulation experiment.The main work of this paper is as follows:1.An ultra-wideband miniaturized Quasi-Yagi antenna based on the characteristic mode theory is designed.The antenna structure is modified according to the characteristic current distribution of the traditional Quasi-Yagi antenna.The results show that the S₁₁ of the antenna in the range of 0.78-1.51GHz is less than-10d B,compared with the initial antenna,the relative bandwidth increases from 32.0%to 67.8%,and the peak gain reaches 5.4d Bi.The results of antenna processing are in good agreement with the simulation,which can be applied to the detection of human brain functional areas.2.A wideband miniaturized directional antenna based on characteristic mode theory is designed.Different from the design method of the first antenna,this antenna design uses characteristic mode parameters to characterize antenna orientation,adopts mode tracking technology and combines optimization algorithm to automatically optimize the antenna,which is more universal.The working frequency band moves to low frequency,to achieve miniaturization.The antenna bandwidth moves from 1.3-1.55GHz（relative bandwidth17.5%）to 0.73-1.18GHz（relative bandwidth 47.1%）,the relative bandwidth increases by29.6%,and the in-band gain is 1.16-5.36d Bi.The designed antenna has good performance and meets the requirement of brain function detection.3.The simulation study of microwave detection of multiple brain functional regions was carried out.In the case of specific absorption rate（SAR）simulation analysis confirming the safety of microwave detection,an ultra-wideband miniaturized Quasi-Yagi antenna was used to form a 6-unit ring antenna array around an accurate 3D human head model.The activities of visual,auditory,tactile,and simultaneous activities of the brain were simulated and analyzed.The scattering properties of different directions are compared,and their characteristic frequencies are extracted.The results show that microwave can effectively detect the activity of single or multiple brain functional regions under the premise of ensuring safety.4.The simulation experiment of multiple brain functional regions detected by microwave was carried out.The medical human head model,antenna bracket,ultra-wideband miniaturized Quasi-Yagi antenna and vector network analyzer were used to build a simulation experiment platform for brain function region detection.Different concentrations of Na Cl solution were used to simulate the state of brain functional regions when they were active.The simulated solution was added to the corresponding positions of brain functional regions successively,and the antenna was used to detect the visual excitatory region,auditory excitatory region,tactile excitatory region and the three kinds of excitatory regions combined.The results show that the change rule of the actual test is consistent with that of the simulation.Microwave can effectively detect the activity of different number of brain functional regions in different locations.