Design Of Human Body’s Impedance Measuring System Based On Virtual Instrument

Human body’s impedance is a parameter which represents the electrical quality of the whole human body or part of the human body, such as human apparatus, cell and etc. We can know the biologic status and clinical status through Human body’s impedance. Human body’s impedance measuring technology has many advantages, such as non-invasive、low-cost、safety、nontoxic、hurtless、easy to operate and wealth of information. Function evaluation of heart、brain、lung and circulation system could be achieved using this technique, so it has extensive application perspective.In this paper, the design of the Human body’s impedance measurement system based on virtual instrument is composed by two parts of the impedance signal conditioning circuitry and analysis software, using the four-electrode method for measurement of body impedance real and imaginary parts.Collection and analysis interface is programmed by Lab VIEW, it is composed of six functional modules:user login, patient information management, data sampling and display, impedance signal sampling, waveform pretreatment, feature extraction and pathological analysis.User login module can avoid unauthorized users to access the system, and theft of patient information. Patient information management module can enter some basic information for patients, such as name、gender、age、health status etc. Impedance signals and user’s information can be saved and displayed in the impedance signal sampling module. The waveform pretreatment module use weighted average method eliminate the breathing wave interference, completes the baseline drift correction signal.The feature extraction module completed of the impedance signal frequency, amplitude, phase extraction. At last, the pathological analysis module can show that the basic information of patient, the impedance waveform, characteristic parameters and analytical results.