Design And Implementation Of Bioelectric Stimulation System Based On Impedance Feedback

With the rapid development of biological science and technology,biomedical engineering has received extensive attention and research.Because of its portability,low cost and simple operation,bioelectric stimulator has become an important experimental instrument in biological physiological pharmacology research,and has been widely used in animal experiments.The existing stimulators mostly adopt open loop control structure and single waveform output,which has the disadvantages of low precision,poor tunability and instability.Therefore,the design and development of a high-precision,multi-functional,with visual function of biological stimulator has important practical value,the specific work is as follows:(1)Research on bioelectrical impedance characteristic parameters extraction based on improved genetic algorithm.For the problem that the traditional genetic algorithm converges slowly and easily falls into the local optimal solution,this method analyzes the characteristics of the population individual,especially the elite individual,redefines the fitness function with the least absolute deviation,and formulates the elite retention strategy.It analyzes the standard impedance data set and the actual measurement,and establishes three kinds of simulation data sets according to the actual situation by adding singularity and random noise.Based on simulation data sets,experiments were carried out to compare the fitting results of the proposed algorithm with the other three algorithms.The results show that the proposed algorithm has the advantages of high fitting accuracy and robust,which provides an effective tool for the comprehensive and accurate analysis of physiological and pathological states of biological tissues.(2)Design a high-precision multi-waveform biological stimulation system based on impedance feedback and high-precision current feedback.Firstly,the high voltage multiwaveform scheme based on high voltage operational amplifier and numerical control waveform algorithm is designed to realize sinusoidal,square,triangular and customizable arbitrary waveform programming output.Then,for high precision control requirements,impedance feedback and high precision weak current measurement technology are used to realize constant current or constant voltage control of output waveform,which can effectively avoid the problem of unstable stimulation current caused by impedance change.And then,for multi-stimulator synchronous output requirements,use single synchronous bus technology to achieve microsecond synchronization effect.Finally,by introducing GPRS communication technology,the remote communication system is designed to realize the remote networking function of the device.(3)Build stimulation system test platform to verify system performance.Firstly,according to the stimulator function,the corresponding test method is designed to complete the experimental test system construction.Then,under the given impedance load mode,the output waveform is verified by parameter performance.The experimental results show that the system index meets the design requirements.Finally,the mouse viscera is used as the experimental object to further verify the bioimpedance feature parameter extraction algorithm.The results show that the actual extracted feature parameters match the impedance theory model and prove the effectiveness of the method.