Study on changes of characteristic parameters of biological tissues impedance spectroscopy in vitro within 5 to 360 min after excision at the frequency range from 1Hz to 1MHz.

We constructed an impedance spectroscopy measurement system based on frequency response analyzer. Using four-terminal method, we measured impedance spectroscopy of rabbit different tissues in vitro within 5 to 360 minutes after excision at the frequency range from 1Hz to 1MHz. According to the measurement results, we analyzed the changes of characteristic parameters (Ro, R_infin, f_c and alpha) of different tissues in the time course. The results show that the Cole-Cole model characteristic parameters change notably in the time course. The value of Ro change great especially. For kidney, liver, spleen and heart, the value of Ro reached 700%, 125%, 170% and 200% respectively at the 6 hour after excision. The change of alpha is less than 30% for all tissues. The changes of f_c are various remarkably for different tissues, for liver, kidney and heart, the value of f_c decreased continually and the decrement reached 60%, 19%, 33% respectively at the end of the measurement. For muscle (longitudinal, transverse) and heart, the value of f_c decreased firstly and then began to increase and reached 145% > 155% > 125% at 6 hour after excision. The results of our reaching show the measurement time plays a remarkable effect on the impedance spectroscopy measurement of tissue in vitro. We hypothesized that the dispersion observed in the impedance spectroscopy measurement in vitro between different researchers was partly due to the effect of measurement time.