Repetitive Transcranial Magnetic Stimulation System Design Based On Eccentric Coils And Pulsed Power Sources

In recent decades,non-invasive brain stimulation techniques have been used to treat various brain diseases.Transcranial Magnetic Stimulation(TMS)and Transcranial Direct Current Stimulation(t DCS)are developing rapidly and becoming the main direction of brain regulation techniques.Although t DCS has been widely used in epilepsy,cerebral palsy and other diseases,but in the process of use will make patients tingling,itching and other discomfort.TMS can regulate cerebral cortical excitability by generating huge time-varying current in the stimulation coil to generate corresponding time-varying magnetic field.Due to its non-invasive,low discomfort,deep stimulation and other significant advantages,it has been widely used in psychiatry,neurophysiology and other fields.With the proposal of magnetic shock technology,its high stimulation intensity and high frequency of stimulation demand put forward new requirements for transcranial magnetic stimulation equipment.In this paper,a set of transcranial magnetic stimulation system supporting high frequency and large magnetic field intensity will be designed.First of all,under the same power drive,the existing 8-figure coil has higher stimulus intensity but poor focusing line,O-shape coil has better focusing but the stimulus intensity is much lower than 8-figure coil,aiming at this problem,the eccentric coil is proposed,the size structure of the coil is redesigned,and the three-dimensional model is established by COMSOL.Through finite element analysis and pulse voltage applied to the coil,the stimulation intensity and stimulation depth of the coil were analyzed,and the design requirements for the power supply of the transcranial magnetic stimulation instrument were put forwardSecondly,in view of the low power supply,slow charging and poor utilization efficiency of the transcranial magnetic stimulation instrument,the power supply was redesigned according to the requirements of the new coil.With STM32F103ZET6 as the core,LLC high-frequency resonant charging circuit,thyristor based pulse discharge system and energy recovery circuit are analyzed and designed.The optimal selection of energy storage capacitor is determined by combining the energy loss of coil single stimulation and actual volume,and the control system of signal detection and switchdrive and other related control circuits is designed.Finally,the stimulation effect of the transcranial magnetic stimulation instrument is simulated and verified by experiments.Firstly,the design parameters of the power supply are tested to analyze whether its output voltage and charging speed meet the design requirements.Secondly,the sample of eccentric coil is developed and tested in conjunction with the power supply,so as to verify the availability of the transcranial magnetic stimulation equipment.