High Accuracy Biological Impedance Measurement System Design and Calibration

The application of biological impedance measurement demands for high-accuracy and fast-speed. A novel measurement system for biological impedance measurement based on automatic balancing bridge is proposed. Besides the improvement on accuracy introduced by bridge method, the utilization of the Least Mean Square (LMS) method guarantees the measurement speed. We designed calibration method to eliminate the error inducted by the practical circuit. The test results reveal the in-phase and quadrature component measurement errors of the proposed system with calibration are respectively lower than 2 percent and 3.2 percent in the range of 1KHz to 1MHz. The system has advantages of high-accuracy and fast-speed which fit for biological impedance measurement applications.