Development And Application Of Wearable Multichannel EEG Recording Combined With Neural Stimulation System

Neuromodulation refers to the technology of interfering with the activity of neurons by means of light,electricity,magnetism,sound and so on.It has important research and application value in the analysis of brain neurological circuits,treatment of brain neurological diseases and neurological rehabilitation.At present,mainstream neuromodulation technologies include deep brain stimulation,transcranial electrical stimulation,transcranial magnetic stimulation,optogenetic stimulation,and ultrasonic neuromodulation and so on,and a new kind of non-invasive neural electrical stimulation technology called temporal interference(TI)stimulation developed in recent years is based on the principle that two sets of high-frequency alternating current that do not interfere with each other work together on the brain to form a slow-wave envelope stimulation pulse in the deep part of the brain to intervene in neurons.Compared with traditional transcranial electrical stimulation technology,the technology may be more focused on the brain's non-invasive deep neuromodulation.It has great research and medical application value for future personalized,wearable noninvasive neuromodulation medical electronics application scenarios.However,at present,there is no system solution which can realize miniaturization,high integration and close loop neuromodulation with the recording of brain nerve activity.In order to realize the closed-loop neuromodulation system based on temporal interference stimulation combined with the recording of brain nerve activity,not only the closed-loop control should be realized,but also two functions should be integrated: 1)the neuromodulation based multi-channel electrical stimulation;2)the neural feedback can be achieved by recording brain neural activity.Recording electroencephalogram(EEG)is one of the common ways to obtain the state of the brain.The technology is mature,and it is widely used in clinical brain disease diagnosis and simple to implement and has high accuracy.Therefore,this subject designed a wearable multi-channel EEG recording combined with neural stimulation system.The main research contents include:(1)Proposing non-invasive deep brain stimulation technology based on direct digital synthesis: direct digital synthesis is used as the core to output high-frequency alternating current signals,and differential amplification suppresses common-mode noise,and low-pass filter reduces high-frequency noise,and reverse current driver balances electric charge realizing the miniaturization of noninvasive deep brain stimulation equipment,which can further expand the application of noninvasive deep brain stimulation in scientific research and medical fields.At the same time,it can also achieve transcranial alternating current electrical stimulation to the two brain areas,and improve the efficiency of brain neural regulation by frequency coupling of different brain areas.(2)Proposing multi-channel EEG recording combined with neural stimulation technology: multi-channel EEG recording and neural stimulation are combined,and the multi-channel EEG data is recorded in a non-invasive way,and the neural activity status of multiple brain areas in the brain is obtained after analysis.At the same time,it can also apply neural stimulation to multiple brain areas in a non-invasive way,which solves the blindness of traditional open-loop neuromodulation technology and achieves real-time and high-precision neural stimulation.(3)Realizing a wearable multi-channel EEG recording combined with neural stimulation system: including hardware,embedded software,and software in PC,the design of the system hardware adopts a modular design,which is divided into a control module,an EEG recording module,and electrical stimulation module,wireless communication module,power management module.With embedded microcontroller unit STM32 as the core,using the front-end amplifier ADS1299 to collect multi-channel EEG,the signal generator outputs multi-channel alternating current signals,while using wireless data communication,and controling power consumption,circuit integration and other technologies realize the wearability of the system,and the final system volume is 5.7cm*4cm.The embedded software of the system is written based on the microcontroller unit STM32,which completes functions such as electrical stimulation,EEG recording,and power consumption control.The software in PC completes the functional interaction with the hardware.The software uses a layered structure design,using the WPF(Windows Presentation Foundation)framework on visual studio 2015 to implement the software interaction layer and C# language to implement the software logic layer.The system not only makes up for the shortcomings of non-invasive deep brain stimulation technology,but also realizes the miniaturization of non-invasive deep brain stimulation technology,and also realizes the basics of closed-loop,personalized neuromodulation.After completing the research and development of the system,this thesis preliminarily verifies the functions of the system,including multi-channel EEG recording and multi-channel electrical stimulation,and carries out experiments related to EEG recording in human body,which verifies the completion of the EEG recoring function.Experiments related to electrical stimulation are carried out step by step in pure resistance circuit,aqueous solution environment and mouse experiment,which verifies the completion of the electrical stimulation function.At last,the simulation model system is established based on the real human brain MRI(Magnetic Resonance Imaging)data,and TI simulation experiment is completed,which provides the basis for the future real human brain model experiment and a safe,reliable,low-cost,excellenteffect of technical solutions for the future diagnosis and treatment of brain diseases.