Accuracy improvement by A three-reference calibration algorithm for a bioimpedance spectrometer

Accurate measurement of complex impedance in a wide frequency range is the foundation of bioimpedance spectroscopy technique. In order to improve the accuracy of a portable bioimpedance spectrometer (BIS) by correcting the systematic errors mathematically, a low cost and accurate three-reference calibration (TRC) algorithm based on quadratic Lagrange interpolation is applied. The principle of the TRC algorithm and the selection of the three RC calibration references are expounded and experimental measurements on a RC measurand are carried out to evaluate the performance of the TRC algorithm. The results find a good agreement between the calibrated data based on the TRC algorithm using the original data measured by the BIS and the standard data measured by impedance analyzer HP4194, with a maximum magnitude error of 0.34% and a maximum phase error of 0.26□ over the frequencies from 20 kHz to 1 MHz. The selection strategy of the calibration references is discussed.