Development Of An Implantable Epidural Spinal Cord Stimulator With EMG Biofeedback

Spinal cord injury (SCI) is the most harmful complication of vertebral column injury,and leads to serious motor dysfunction of the limbs below the injured level. Thedevelopment of medical care results in the significant rise of the survival rate and thesurvival time after medical treatment, so that the disability rate increases.There is no methods to cure the sequelae caused by SCI completely yet, but manymethods can promote the recovery of motor function after SCI. Studies has shown thatepidural spinal cord stimulation (ESCS) in conjunction with weight loss exercise trainingcan improve patients’ motor function of lower limbs. ESCS means a kind of technologythat sending electrical stimulation pulses with special parameter to the spinal cord by theelectrode implanted in the spinal epidural gap, to stimulate the central nervous tissuedirectly. In this way, we can realize the intervention of the central nervous tissue.In this thesis, I made brief explanation for ESCS and electromyographic signal, andintroduced some theoretical knowledge, including the research status of ESCS andelectromyographic signal, the function of ESCS for motor function, the feature extractionand analysis method of electromyographic signal, etc. This thesis provided the designproposal of new-type spinal cord stimulator with electromyographic signal biofeedbacksystem, and introduced the design of this system’s each module and the implementation ofthe hardware and software in detail. This thesis primarily validated the rationality of thedesign scheme and the feasibility of receiving the implantable EMG outside the body withwireless communication, by collecting and transmitting the surface electromyography(sEMG) instead of the implantable EMG.The stimulation system includes implantable spinal cord stimulator, externalcontroller and upper computer. This system can analyze the EMG signal in time andfrequency domain, and set the implantable spinal cord stimulator’s stimulus parameter,when it is stimulating the spinal. The implantable spinal cord stimulator part includes themicrocontroller, EMG signal amplification module, electrical stimulation module andwireless communication module, etc. This stimulator could set stimulus parameter bywireless communication, which is very small in size and low cost. The stimulatorgenerates the biphasic charge-balanced voltage-regulated pulses, which are delivered to the bipolar electrode by the lead extension to achieve chronic ESCS. The design anddebugging of the stimulation system’s software is being carried out in the developmentenvironment of integrated Silicon Laboratories IDE. The stimulation waveforms withdifferent parameters are gained through the software of the electrical stimulation module.This thesis describes the design of upper computer software, which is used in analysis ofonline and offline analysis of EMG signal, and set of the stimulator’s stimulus parameters.The software can realize electromyographic signal’s acquisition, filtering, storage,playback, time and frequency domain analysis, and setting of stimulus parameters. Thisthesis tested the system by using the sEMG of human body as signal input, and validatedits feasibility.