Design Of EEG-NIRS Signalacquisitionand Processing System In Rats

Near-infrared spectroscopy as a new method of brain function monitoring in recent decades has provided a feasible and effective new method for revealing brain mysteries and detecting brain diseases.It uses near-infrared light that is harmless to the human body.By measuring the changes in the concentration of deoxyhemoglobin,oxyhemoglobin and total hemoglobin in the brain's internal tissue,the specific algorithm is shown on the parameter change.The experimenter determines the specific brain function status by analyzing the parameters.The development of EEG is widely used in the fields of scientific research and medical aid.However,with the rapid changes in medical means,some new drugs have also been developed,and these can not be directly in the human body to verify under the condition of uncertain treatment effect,then you need to do experiments in experimental animals.Mice with the human physiology is very high degree of similarity,so in mice to verify is more appropriate.But for the mouse brain monitoring equipment is far better for the improvement of human beings,but also mostly inaccurate,the mouse head of the limited area also led to a relatively single technology.Therefore,this paper developed a STM32-based embedded system and MATLAB GUI-based PC software package of experimental monitoring equipment for monitoring the physiological state of the brain,the specific work is as follows:Firstly,in the aspect of data processing,the low-pass,high-pass and frequency trapping processing of EEG signal is discussed and and do the simulation map.The digital filtering method which is most suitable for EEG real-time monitoring is determined.The formula for calculating the change of oxyhemoglobin and deoxyhemoglobin concentration is deduced based on the modified Lambert-Beer law for the NIRS signal.Then,the hardware circuit design of EEG and NIRS signal acquisition part is introduced in detail.The hardware circuit is based on STM32F103 series chip as the core components,the whole circuit including power supply circuit,EEG signal amplification and filter circuit,LED drive circuit,NIRS signal emitting photoelectric conversion circuit,A/D acquisitioncircuit,Bluetooth communication circuit,electrode design circuit,front-end probe electrode device,each part of the circuit in detail.And the LED driver,A/D acquisition and read,data package,data transmission program design are explained step by step.Then,the software based on MATLAB GUI platform is introduced.The function modules mainly include the design of Bluetooth communication parameters,communication protocol,receiving data and processing,storage,marking,display and enlargement.