Measuring System Design, Modeling And Application For Multifrequency Impedance Of Acupuncture Point

Meridian acupoints are usual the application points of Chinese acupuncture and massage. However, the essential properties of meridians are still elusive. Bioelectrical impedance analysis(BIA) are effective and often-used methods to detect physiological and pathological states of biological tissues. And BIA are also one of the most important methods to study the properties of meridian acupoints. Preliminary studies of meridian essences basing on BIA suggest that acupuncture points exhibit a kinds of significantly lower resistance properties compared to the surrounding tissues.Especially, it was reported in many papers that the differences of Bilaterally Symmetrical Acupoints(BSA) impedances are statistically correlated to internal organ health states. These founds agree with the viewpoint of “meridian–viscera correlativity” in meridian theory. But These founds haven’t been ultimately substantiated yet. Concentrating on the problem of further confirmation and applications of these founds, the main studies and innovations in this thesis were listed below:1. A new system for simultaneous measurements of 2-channel BSA multi-frequency impedances was designed. The key features include:(1)a set of five electrodes which two of the electrodes are injected with exciting current signal to synchronously equally excite BSA and the other three are used as sensors to simultaneously sense both sides response signals;(2)a PC based time-domain signal testing platform equipped with functions of arbitrary current waveform generation and three channel signals(one is the exciting current, the other two are the response voltages) simultaneously sampling;(3)a set of Multi-Frequency Impedances(MFI) simultaneously unbiased computing algorithms based on special odd multitsine current signal input;(4) Signal acquisition software platform basing on MATLAB program language.Preliminary validating experiments suggested that the designed system allows to accurately and synchronously measure BSA MFI at least in the frequency range of 10 Hz ~60 kHz. And the obtained BSA MFI are well comparable.2. A robust method for computating the time constant/characteristic frequency of Cole-Cole model was presented. Firstly,0R, R?,? were computed by using circle fitting methods. Then, the ? can be acquired through optimizing the Simplified criteria Function of Square of Sum of Real Part Error, SFSSRPE( Only ? is the variable. It was proved by the auther that there only is one extreme point in this function.) presented in this paper. The fitting results of simulation data and measured data indicated that the methods in these paper are high accurate and robust.3. In order to improve the identification accuracy and reliability of Commensurate Fractional Order Model(CFOM),a Separable Nonlinear Least Squares algorithm with Stable Constraints(SC-SNLS) was presented to optimize the mean square error evaluation criterion. Considering that the CFOM is linear in its numerator polynomial coefficients and are nonlinear in its common fractional derivative order and the denominator polynomial coefficients, the LS and LM algorithms were alternately iteratively used to estimate the linear and the non-linear parameters respectively. Four unstable factors were revealed in estimation procedure through perturbation analysis of the estimation of linear parameter. Then the stability and convergence of optimization procedure can be improved through tackle the unstable factors. Simulation results show that the proposed algorithm has a fast convergence speed and provides more accurate estimation compared to relative approaches.4. Selecting a model that can best describes acupoints MFI from four kinds of models(including integer-order and fractional order models) often used in fitting bioelectrical impedances and applying this model; it was pointed out in this paper that traditional integer-order model order estimation methods are not suitable for order estimation in model groups including integer-order and fractional order models; According to this problem, the paper provided corresponding two principles of model selection; From high priority to low, they were listed below:(1)exclude model that being not easy to set up its equivalent circuit;(2)to compare the drop degree of the fitting errors of two models, if the drop degree is greater than the threshold value, then select the lesser error one, otherwise select the lesser order one; If the order is the same, select the integer model.According to the principles above and statistical analysis of multiple groups of model parameter, second order integer-order model is the best one to describe acupoint MFI. By comparing two groups of second order integer model parameters of bilaterally acupoints of Taixi, it is seen that the difference of patients with urinary tract infections were greater than the healthy group. These statistical regularity have potential to be used to guide disease diagnosis basing on meridian theory more objectively.