Research On Brain Function Area Detection Based On Microwave Scattering Method

Non-invasive detection of brain activity is one of the main topics in the field of brain science today.The research using microwave technology to detect the activity status of brain functional areas has a great significance to the development of human brain science.The main work of the research is as follows:1.The concentration of sodium and potassium ions inside and outside the cell membrane will be changed periodically when the neuronal cells in the functional areas of the brain are in a state of neural excitement,the electrical parameters of the brain tissue will be changed subsequently.The reasons for the changes are analyzed by combining the physiological characteristics of the brain functional areas.The transmission model is established,and the functional relationship between the scattering signal and the dielectric constant and conductivity of the time-varying medium is analyzed and deduced.By deducing the results,it can be concluded that the dynamic characteristics of the medium will cause the same frequency change of the transmission phase of the scattered signal.This result lays the theoretical foundation for the follow-up research.2.The electromagnetic simulation software is used to simulate the microwave detection of the brain's tactile functional areas and the visual functional areas,and the three-dimensional high-precision brain model is introduced into the electromagnetic simulation software,and configure the corresponding parameters for the brain model according to the real electrical parameter characteristics of the human brain in the microwave state.The parameterizable media block is embedded in the corresponding position of human brain functional area,which is given time-varying characteristics to simulate the neural activity of the functional area.According to the frequency of the EEG signal,the duration of the neural activity in the functional area is set to 1 second,the solution step is set to 0.01 second.Therefore,101 iterations of calculation are required and the results of each calculation are retained.The safety of microwave detection under certain power conditions was proved by the specific absorption rate(SAR)simulation analysis.The scattered signals received by the Vivaldi antenna in different directions around the human brain were processed and analyzed.The results showed that based on the microwave scattering method,the activity state of brain functional areas can be effectively detected under the premise of ensuring safety.3.A conformal antenna array test platform for brain function area detection is designed,which includes a miniaturized,high-gain Vivaldi antenna,a broadband radio frequency switch circuit,and a conformal antenna array support.The radiation characteristics of the antenna in the low frequency band are improved by adopting a method of loading a circular arc reflector on the ground layer without changing the size of the original antenna.The results show that the standing wave ratio is less than 2 in 1-3GHz,the gain is greater than 4d Bi,and the peak gain reaches 5.5d Bi.Based on the PE42482A-X RF chip and STC15F2K60S2 microcontroller,the broadband RF switch circuit is designed,and the RF switch circuit is processed and measured.Within 1-3GHz,the insertion loss between the ports is less than 2d B,and the isolation is greater than 20 d B.Finally,a conformal antenna array bracket for brain functional area detection was designed and printed by using 3D printing technology.4.The brain function area simulation experiment based on the microwave scattering method was carried out,and different concentrations simulation solution of brain function were configured to simulate the different states of the brain function area activity.With the help of a three-dimensional high-precision human brain bionic model,the biomimetic for simulating brain tissue is configured inside the model according to a certain ratio,simulation solution of brain function with different concentrations were added to the corresponding positions of the brain function area respectively,and the scattered signals received by the Vivaldi antenna in different directions around the human brain model were analyzed,it indicates that the variation of the scattered signal's phase will be caused by the change of the electricity parameters of the brain function area.The actual test results are in good agreement with the simulation results,which indicates that the activity status and status information of the brain functional areas can be effectively detected and extracted through the microwave scattering method.