Design And Implementation Of Microvolt Level EMG And Evoked Potential Device

EMG and evoked potential (EP) are recorded electrical activities generated by stimuli on auditory system, visual system, somatosensory system and brain cortex on the corresponding body surface.Being able to reflect the functional status of the nerve pathways with respect to auditory, visual, somatosensory and motor systems, EMG and EP can be employed to determine the lesion site and severity, and thus can provide clinical guidance to the doctors during the process of diagnosis and treatment. Compared with their abroad counterparts, the performance of EMG and EP instruments in China, while at the preliminary stage,are not good enough in terms of anti-interference, accuracy and timeliness.Therefore, undergoing R&D on EMG and EP instruments with high precision and fast reaction time is not only important on its own, but also helpful to raise the R&D level of domestic medical devices.Since the magnitude of EMG and EP is of only the order of microvolt,the signals of EMG and EP are prone to be submerged in the ambient noise,internal system noise, and other electrophysiological signal.Moreover, the required acquisition frequency can be up to250KHz, which demands a relatively high synchronization speed. Therefore, precise amplification technique, high speed real-time synchronous data acquisition technology and high speed real-time communication are the three core technologies required when developing the instruments. This thesis focuses on1)the research and analysis of the FPGA-based data collection process involving high speed synchronous collection and high speed real-time data flow cache transmission processing, and2) the design of multi-channel real-time synchronous data transmission based on parallel communication interface. The developed EMG and EP instrument can perform reliable synchronous data transmission with high speed with PC.Based on a dual-core CPU controller design platform, the core hardware architecture is designed consisting of amplification, stimulation and data collection modules. The function of the stimulator is to generate an adjustable electrical current to stimulate the body. The generated current can induce the desired EMG or EP signals, which are then fed into the amplifier. The function of the FPGA-based real-time synchronous data acquisition module is to cache the data flow and transmit it through parallel port communication to the ARM host controller, which finally sends the collected data to the host computer responsible for real-time display of signals. This design not only breaks the limitations of the technology for data collection cache transmission processing, but also improves the microvolt signal detection technology with a large safety factor, high anti-interference ability and high reliability.The test results on the developed prototype show that the design of EMG and EP instrument system is feasible to meet the requirement of medical research and clinical needs.The core technology can enhance the competency of independent innovation of domestic biomedical instrumentation, and has some commercialization potential.