A Study On Noninvasively Transcutaneous Spinal Cord Stimulation System

Transcutaneous spinal cord stimulation(tSCS)can treat chronic pain and promote motor function recovery after spinal cord injury.The influence of tSCS on nerve fibers was studied by computer simulation.It can provide reference for the selection of tSCS stimulation parameters in clinical application.In this thesis,a simulation study of electrical stimulation of spinal cord nerve was carried out and a portable electrical stimulator was designed.Firstly,a finite element model of the human lumbosacral segment under tSCS was created.The solver was used to calculate the extra-membrane potential along the axon of the neuron,and the extracellular potential at the Ranvier node on the axon of neurons was obtained by interpolating in Matlab.The Neuron software was used to establish the human neuron double cable model,and the activation threshold of the nerve fiber was calculated by gradually adjusting the stimulation current.The simulation results showed that the exit of dorsal root fiber at DR1 segment is closest to the stimulation electrode so that activation threshold was minimal.The exit of ventral root fiber from the spinal cord at VR3 segment was closest to the level of vertebral T12 spinous process so that the activation threshold was maximal Furthermore,the activation threshold of nerve fiber decreased with the increased pulse width,whereas the reduced increment of activation threshold decreased with increased pulse width.Therefore,choosing appropriate pulse width is helpful to activate nerve fibers and avoid discomfort due to the large current density in the epidermal layer.This thesis designs a portable current-stimulator that can provide stimulation pulses for clinical trial research.The stimulator waveform and the range of frequency,current intensity and pulse width were determined by simulation results and clinical test parameters in literatures.Then the system structure block diagram was given.Then the hardware design and software design of the system were introduced.Finally,the load capacity test and the human body test were carried out.The results showed that the stimulator can output a stable and accurate stimulation waveform.