Theoretical And Experimential Study On Dynamic Pulse Impedance Spectroscopy

Non-invasive blood component detection has long been the dream of modern medicals, as well as the patients. Undoubtedly, noninvasive method will replace traditional ones because noninvasive means no pain and no hazard of infection. Among all the noninvasive blood component measurement technologies under developed, bio-impedance is the most attracting one because it is easy to use, quick, safe and economical.The main problem bio-impedance must to face is that the impedance measuring accuracy is difficult to improve because of individual variances, measuring conditions and many other factors. Dynamic Pulse Impedance Spectroscopy (DPIS) is efficient to reduce the individual variance. In this dissertation, comprehensive experimental study is made on the factors of individual variance and the results analyzed. An improved DPIS measurement arrangement is discussed thereafter.Firstly, it's concluded that respiration and pulse wave concurrently exist at any location after analysis of the formation of respiration and pulse wave. An improved impedance plethysmography is proposed based on conductivity principle of suspending material and flux law of posieuille, from which the factors that influence measurement accuracy of bio-impedance are theoretically derived, among which respiration wave is the main one.DPIS measurement system demands strict hardware design. Two channel sinusoidal signals which must be strictly orthogonal and frequency programmable is needed. and multi-operational modes, single mode, frequency skip mode, and sweep frequency mode, are necessary for quick measurement.The signal acquired is consist of pulse wave and respiration wave, as well as circuit noisy. The circuit noisy is easy to recognize by modern signal processing method. But respiration wave is difficult to eliminate because it is coherent to the pulse wave. In this dissertation, characteristic segment of pulse wave coherent average and iterative arithmetic are employed to abstract the respiration wave and reduce other noisy and impedance pulse wave with high accuracy is finally plotted.