In order to study the variation of complex impedance and characteristic parameters on human normal and tumor lung tissue during the extracorporeal time, we established a real part-imaginary part chart of complex impedance on lung tissue which provided the basic theory and the reference data for research on elementary medicine and clinical diagnosis of lung cancer and meanwhile provided prior information for electrical impedance tomography (EIT) research. In the experiment carried out in our laboratory, when operation was finished, we kept the lung cancer tissue and normal tissue neatly separated into the cylindrical testing cavities and kept the temperature and humidity at expected values. Then the measurements of complex impedance property are performed at frequency from 1 000 Hz to 30 MHz using 4294A impedance analyzer of Aglient Company. With time changing, the results showed that there was a significant change occurring on the complex impedance of human normal and tumor lung tissue. However, the impedance of normal lung tissue is greater than that of tumor lung tissue. We consider that this change should be related to the change in extracellular fluid, intracellular fluid and cell membrane.
In order to improve the accuracy of blood pressure measurement in wearable devices, this paper presents a method for detecting blood pressure based on multiple parameters of pulse wave. Based on regression analysis between blood pressure and the characteristic parameters of pulse wave, such as the pulse wave transit time (PWTT), cardiac output, coefficient of pulse wave, the average slope of the ascending branch, heart rate, etc. we established a model to calculate blood pressure. For overcoming the application deficiencies caused by measuring ECG in wearable device, such as replacing electrodes and ECG lead sets which are not convenient, we calculated the PWTT with heart sound as reference (PWTTPCG). We experimentally verified the detection of blood pressure based on PWTTPCG and based on multiple parameters of pulse wave. The experiment results showed that it was feasible to calculate the PWTT from PWTTPCG. The mean measurement error of the systolic and diastolic blood pressure calculated by the model based on multiple parameters of pulse wave is 1.62 mm Hg and 1.12 mm Hg, increased by 57% and 53% compared to those of the model based on simple parameter. This method has more measurement accuracy.