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Error analysis of tissue resistivity measurement
Author(s)
Tsai, Jang Zern
Will, James A.
Stelle, Scott Hubbard Van
Cao, Hong
Choy, Young Bin
Haemmerich, Dieter
Vorperian, Vicken R.
Webster, John G.
Date Issued
April 30, 2002
Type
Article
Abstract
We identified the error sources in a system for measuring tissue resistivity at eight frequencies from 1 Hz to 1 MHz using the four-terminal method. We expressed the measured resistivity with an analytical formula containing all error terms. We conducted practical error measurements with in-vivo and bench-top experiments. We averaged errors at all frequencies for all measurements. The standard deviations of error of the quantization error of the 8-bit digital oscilloscope with voltage averaging, the nonideality of the circuit, the in-vivo motion artifact and electrical interference combined to yield an error of ±1.19%. The dimension error in measuring the syringe tube for measuring the reference saline resistivity added ±1.32% error. The estimation of the working probe constant by interpolating a set of probe constants measured in reference saline solutions added ±0.48% error. The difference in the current magnitudes used during the probe calibration and that during the tissue resistivity measurement caused ±0.14% error. Variation of the electrode spacing, alignment, and electrode surface property due to the insertion of electrodes into the tissue caused ±0.61% error. We combined the above errors to yield an overall standard deviation error of the measured tissue resistivity of ±1.96%.
Citation
IEEE Transactions on Biomedical Engineering, 49(5), 484-494, 2002