| According to the statistics published by World Health Organization,there are about 10 million new patients with nervous system diseases.In some developing countries,poverty,malnutrition and lack of medical resources results in severe situation of nervous system diseases.Currently,the most common nervous system diseases are epilepsy Alzheimer’s disease,apoplexy,migraine,tinnitus,depression and drug addiction.Transcranial electrical stimulation is proved to be a non-intrusive and safe medical treatment designed for nervous system diseases,continuously acting on some patients to relieve different nervous system diseases.Some researchers also studied the effect of transcranial electrical stimulation on human cognitive system.Multiple trials have also proved that transcranial electrical stimulation has great potential in improving human working memory,skills acquisition,attention,etc.Traditional transcranial electrical stimulation devices have poor consistency in small signal output,incapability of outputting dual-channel phase amplitude coupling with one single device,high power consumption and other problems.In this thesis,a new dual-channel phase amplitude coupling transcranial electrical stimulation is designed.Firstly,the dual-channel phase amplitude coupling stimulation signal output can be controlled by the program so that dual-channel phase amplitude coupling stimulation signals can be outputted simultaneously.Secondly,the new current following module was designed on the basis of the Howland current following module so that the module output impedance became higher,unchanged by the human body resistance and compatible with highresolution electrodes.This current following module is less influenced by the acceptance off-size of the components and devices in manufacturing,resulting in higher compatibility with the equipment.Besides,in order to address the higher power consumption of the traditional devices,this design was improved in the software algorithm level and a narrow pulse group with lower power consumption was used for output stimulus waveform.The referred upgraded designs were applied and verified in a 32-bit microprocessor,GD32F170,of Gigadevice Semiconductor(Beijing)Inc.Tests prove that this device is capable of reach the design index.Finally,the one-month randomized clinical trial on the effect of transcranial electrical stimulation on the associative memory ability in learning second foreign language was conducted.With the functional magnetic resonance imaging statistics as the reference,this trial creatively proposed to select P3 and F3 as the most potential targets for enhancing memory and a 20-minute 1.5m A t DCS trial was conducted on 15 volunteers who had never learned German.The effects of t DCS on memory ability in different conditions were compared and analyzed.The results indicate that t DCS is inductive to improve the associative memory and learning ability of the volunteers. |
