Research On Multimodal Brain Signal Detection System Based On EEG FNIRS

At present,the common brain detection technologies include electroencephalogram(EEG),functional near-infrared spectroscopy(fNIRS),functional magnetic resonance imaging(f MRI)and other technologies.However,these traditional brain detection technologies detect single mode signals,and single mode signals often have deficiencies that cannot be remedied by themselves.The understanding of the brain has limitations,which can no longer meet the comprehensive and detailed exploration of the brain.To solve the above problems,this paper designs and develops a multimodal brain signal detection system based on EEG fNIRS.The system combines EEG and functional near-infrared spectroscopy(fNIRS),two widely used non-invasive detection technologies,to simultaneously detect EEG signals formed by neuronal discharges and cerebral blood oxygen signals related to hemodynamic activities.Combining the advantages of EEG’s high temporal resolution and fNIRS’ high spatial resolution,the system avoids the disadvantages of EEG’s poor spatial resolution and fNIRS’ poor temporal resolution,and achieves complementary advantages and disadvantages,To some extent,it avoids misleading results caused by interference signals of single detection technology,improves the reliability of brain detection,and provides rich information and built-in verification for comprehensive exploration of brain functional activities.The specific research contents are as follows:1.Research and development of EEG fNIRS multi-mode brain signal detection system: the system can collect EEG and cerebral blood oxygen signals at the same time,realizing EEG acquisition with 32 channels and a single channel sampling rate up to 16 k Hz,and cerebral blood oxygen acquisition with a maximum support of 16 channel light source,16 channel detector and a single channel sampling rate up to100 Hz.Among them,the EEG acquisition channel can be expanded to 1024 channels at most,and the single channel sampling rate is 500 Hz at most.The front-end circuit module at the electrode side amplifies and low-pass filters the original EEG signal,improving the signal to noise ratio;The cerebral blood oxygen acquisition can flexibly adjust the luminous frequency,luminous power of the light source module and the switching of the emission light of different wavelengths.In addition,a wireless communication protocol based on CRC verification was specially designed to ensure the high availability of the system and the accuracy and effectiveness of data transmission.The system performance test and the classic human forearm blood block experiment of this EEG fNIRS multi-mode brain signal detection system were carried out to verify its effectiveness.2.Optimization design of the physical structure of the system: The topological structure of the EEG fNIRS multimodal brain signal detection system was studied and optimized,including the miniaturization of the EEG dry electrode and the electrode back-end circuit into an EEG electrode module,3D printing design of the photoelectric probe used to fix the light source and photodetector,avoid the interference of ambient light,and the flexible lightweight forehead strap.And based on the relevant research on the activity of the prefrontal brain region,the site layout of the fixation band was optimized to achieve the need to cover the active brain region as much as possible.The structure of the system is optimized to ensure the close fitting between the acquisition module and the scalp,avoid relative displacement,and meet the system design requirements of miniaturization,portability and easy wearing.3.To verify the feasibility of the detection system: The designed EEG fNIRS multi-mode brain signal detection system is used to conduct visual stimulation experiment in vivo,which verifies the effectiveness and functionality of the system.On the visual stimulation experimental platform designed by Psychtoolbox,the subjects completed the visual stimulation paradigm designed in this paper.The experimental results are consistent with the results of domestic and foreign literature,indicating that the system can effectively detect the EEG signal and cerebral blood oxygen signal when the brain nerve activity.