Design And Realization Of Portable Transcrannial Direct Current Stimulation System

Nervous system diseases have a very high incidence,disability and mortality in the world.How to treat the nervous system diseases of nervous more effectively,reduce the patients’ pain and improve the life quality of patients is a hot topic in the field of neuroscience research.Currently,many studies show that the clinical therapy of transcranial direct current stimulation(tDCS)on nervous system diseases has a positive effect.German NeuroConn and United States Soterix companies’ tDCS products are widely used,but there is few professional tDCS products in domestic market.The companies of NeuroConn and Soterix have developed a kind of portable tDCS product,the stimulus parameters can be adjustable only after connecting to the computer,and the tDCS product has no charging interface.Therefore,a safe and reliable portable tDCS system with low power,Micro USB,digitally adjustable stimulating parameters,a variety of stimulus patterns is designed in this work.The tDCS system mainly includes hardware circuit and human-computer interaction interface.Hardware circuit design contains a digital adjustable current source circuit,real-timely monitoring current of the over-current protection circuit and high-precision impedance detection circuit.Current source circuit is the basis of the whole tDCS system.The current output error is less than 20μA in the range of 0 ~ 1mA.The current output error is less than 50μA in the range of 1mA ~ 2mA.The minimum current step is 50μA.The overcurrent protection circuit can monitor the current amplitude of the stimulus period in real time,ensuring that the stimulus current is within the human safety threshold.The function of the impedance detection circuit is to detect the contact impedance between the electrode and the scalp.When impedance is below 3.92kΩ,the error of the impedance detection is less than 70Ω.In addition,the tDCS system has automatic increase or decrease function.When the change of current amplitude is large,the current amplitude of the system will gradually increase or decrease to setpoint.Therefore,the user does not feel severe tingling due to the automatic function.The maximum power consumption of the portable t DCS prototype designed in this thesis is about 600 mW,and its continuous woking is about 12 hours.In this thesis,various parameters of the portable tDCS prototype were tested,which met the human body electrical safety standards.In addition,the validity and reliability of the portable tDCS prototype were verified,using a tDCS experiment(health subjects).In conclusion,the portable tDCS prototype has a potential to provide a current-stimulation system platform for clinical experiment and treatment of neurological diseases.