Design Of Human Body's Electrical Impedance Measurement System

Bioelectric Impedance Measuring Technology is a non-invasive detectingtechnique which extracts biomedical information relating to human body'sphysiological and pathology status, through the change of electrical characters(impedance, admittance, permittivity) in biological tissue and organ. This technologyhas many advantages, such as non-invasive, low-cost, safety, nontoxic, hurtless, easyto operate and wealth of information. Function evaluation of heart, brain, lung andcirculation system could be achieved using this technique, so it has extensiveapplication perspective. At present, the exciting frequency of Bioelectric Impedance Measuring System isgenerally below several hundreds KHz. The measuring system which excitingfrequency range is from 1MHz to 5MHz and can penetrate cell-membrane to extractthe intracellular information remains to be settled. According to above situation, author designed a multi-frequency human body'simpedance measuring system from 0 1MHz. The key controller of this system isTMS320F206. To solve the problem, the reference point is difficult to choose, authorpresented a demodulation method, named visual reference point . With this method,the system can measure the real part and image part of human body's impedancethrough four-electrode method. This paper introduces the principle of operation, hardware and software designsof this human body's impedance measuring system. Measurements based on R-Cthree components simulation network were performed with this system. Theexperiment results and error analysis had also be done. Finally, some improvement suggestions were presented at the end of thesis.