Simulation Optimization And System Design Of Transcranial Direct Current Stimulation

Transcranial direct current stimulation(TDCS)is a non-invasive brain stimulation technology that uses electrodes attached to the scalp to inject direct current into the brain to achieve changes in excitability of the cerebral cortex and makes a difference to brain functions.In recent years,this technology has been widely used in the treatment and rehabilitation of neurological and psychiatric diseases such as stroke,depression,and mental disorders,as well as in brain science research such as brain function cognitive intervention,which therefore has been rapidly developed.However,the transcranial direct current stimulation technique has a wide stimulation range,and it is difficult to achieve accurate target stimulation.In order to improve the focality of stimulation,that is,to achieve precise target stimulation of single or multiple target brain regions,further optimization of electrode parameters and stimulation methods is required.At the same time,with the aging of population and people’s attention to physical and mental health,more and more people choose community or home rehabilitation therapy.The electrical stimulation equipment produced by large companies is relatively expensive,so the low-cost,easy-to-operate,small and light transcranial electrical stimulation system has become the focus of current demand.In this thesis,a four-layer sphere model and a real head model are constructed.The transcranial direct current stimulation was simulated and optimized in parameters using the finite element method.At the same time,on the basis of simulation and optimization,the system of the transcranial electrical stimulation was designed.The main work is as follows:(1)The working principle of transcranial direct current stimulation was analyzed.The mathematical model was established.The application of the finite element method in the simulation was analyzed.A four-layer sphere model and a real head model was constructed.The transcranial direct current stimulation was simulated using the finite element analysis software.Magnitude and spatial distribution of the electric field in the brain were calculated.(2)Various electrode parameters and stimulation methods were simulated for transcranial direct current stimulation.When applying the sphere model,the transcranial direct current stimulation was simulated and optimized in terms of magnitude of current,electrode spacing,electrode area,electrode shape to improve the focality of stimulation by adjusting the electrode parameters.When applying realistic head model,traditional large-area rectangular electrodes stimulation,high-definition ring electrodes stimulation,electrical stimulation based on lead networks,and array electrodes stimulation were simulated under different electrode parameters.The percentage of pixel area of the effective stimulation area of the brain was used as the stimulus focality index.The effective stimulation area of each stimulation methods and each electrode parameter was compared and analyzed.The stimulation methods and electrode parameters that can improve the focality of stimulation and realize multi-target stimulation are obtained.(3)The system of transcranial electrical stimulation was designed.The signal generation module,control module,display module and power supply module were separately designed and software simulation and system construction were performed,which can output AC current signals such as sine wave,rectangular wave and triangle wave and low-intensity DC current signals to meet requirements of safety,convenience,and accuracy.