High-accuracy Bio-impedance Spectrum Measurement System And Its Application In The Study Of Meridian

Bioelectrical Impedance Measuring Technology (BIMT) is a new technology developed in recent years. Due to the feature of non-invasive, low-cost, safety, nontoxic and harmless, it has extensive application perspective. The special attention is paid to the BIMT technique by the researchers in biomedical engineering and clinical medicine areas. In recent years the BIMT has been widely used in various fields, for instance in the area of meridians and collaterals impedance study.At the same time, the BIMT still has some problems, for example most system use single frequency source that can't give entire imformation; most systems don't use integrate circuit which has more anti-interference capability; most systems base on the Ohm's law, and their accuracy have greater dependence on the current source; most algorithm of software calibration is easy to understand, but it is hard to implement on the low-end CPU.In light of the above, this paper designe a high-accuracy bio-impedance spectrum measurement based on AD5933 which uses high-precision theory such as proportion-measurement and DFT demodulation technique. This method has high integration, and less dependence on the source. And also a method of compensation is proposed on account of the stability of AD5933.The magnitude and phase are compensated separately; and this algorithm can be implemented on the SCM.By designing the hardware and software following the above method, a bio-impedance spectrum system is implemented. This system is used to test the changes of meridians and collaterals impedance spectrum when acupuncturing. The experimental result indicates that when acupuncturing the magnitude pick-up after the first decrease, more in lower frequency and the phase decrease, most at 10KHz.