Design And Research Of Portable Multi-channel Emg Evoked Potential Instrument

The EMG evoked potential instrument can be used to record the electrophysiological activities of human muscles when they are at rest and during muscle contraction.The surface electrode is used to collect the patient’s part to be measured,record the surface EMG signals,and then send the recorded signals to the required instruments.These instruments process and amplify the signals,Finally,a series of related waveforms will be displayed on the screen of the instrument to help doctors.With the rapid development of science and technology,people have a more accurate and in-depth understanding of surface EMG signals.At present,it occupies a very important position in many fields,such as rehabilitation training,clinical diagnosis,basic medical research,and so on.Therefore,there is a high requirement for the acquisition of surface EMG signals.In the process of signal acquisition,the signal will be interfered by some noise factors,which will affect the diagnosis of the disease.Most of the products of domestic companies have certain deficiencies in this respect,poor noise resistance,large volume,and few channels.Therefore,a portable multi-channel electromyography evoked potential instrument is designed in this thesis.The main work of this paper is as follows:(1)In the aspect of hardware,each module of the hardware circuit is designed.In this paper,the preamplifier circuit composed of AD8221 instrument amplifier is used to amplify the signal and suppress the interference caused by common mode signal.High and low pass filter and50 Hz power frequency notch filter are used to filter the high-frequency noise,low-frequency noise and power frequency noise in the signal,and the surface EMG signal after digital analog conversion is transmitted to the upper computer through wireless.(2)In terms of software,the upper computer interface is completed by using C++language.After the data transmitted from the hardware circuit is further processed by the upper computer,the signal waveform display,report printing and other operations can be realized.(3)In terms of algorithm,the wavelet improved threshold function algorithm is adopted.In order to make up for the limitations and shortcomings of the traditional soft and hard threshold functions in signal denoising,the improved wavelet algorithm is used to denoise the signal.By comparing the three functions,the improved wavelet threshold function has obvious advantages in signal denoising.(4)In terms of equipment testing,the preliminary verification operation is carried out for the equipment,including the magnification test,hardware test and the final experimental test.The test results show that the performance indexes of the portable multi-channel EMG evoked potential instrument designed can meet the expected requirements.