Method and apparatus for eliminating loading and electrode polarization effects in impedance measurements for tissues and electrolytes

摘要

A device and method for accurately characterizing tissue impedance employs multiple electrodes at a plurality of separation distances to cancel the effects of front end loading leakage currents and electrode polarization to improve the accuracy of sensitive impedance measurements used to identify cancerous tissues. These measurements may be automated over a range of frequencies.

主权项

1. An apparatus for analysis of tissue comprising:
a signal source producing an electrical signal including a range of frequencies; at least three electrodes positionable at separated points of electrical contact with the tissue; an electrical switch system connecting the signal source to different pairs of the at least three electrodes so that the electrical signal passes through different lengths of tissue: a monitoring circuit configured to communicate with the signal source to measure the electrical signal between an electrode pair connected by the electrical switch to receive the electrical signal; an electronic computer communicating with the monitoring circuit and configured to execute a stored program to: (a) measure the electrical signal between at least two different electrode pairs having different separation distances at corresponding points of electrical contact with the tissue; (b) use the measurements of the electrical signals at the different separation distances and use values of the different separation distances to provide an impedance measurement of the tissue between at least two electrodes corrected for electrode polarization; wherein the electronic computer performs the step of (b) by: determining at least two points of a function relating the measurements of the electrical signal to separation distance; extrapolating the function to a separation distance of zero; and correcting the impedance measurement of the tissue between at least two electrodes using the extrapolated value of the function.