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Conductivity differences distort probe measurements of magnetically induced electric fields
Author(s) -
Miller Douglas L.
Publication year - 1994
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.2250150510
Subject(s) - conductivity , sigma , electric field , electrical resistivity and conductivity , petri dish , magnetic field , coupling (piping) , materials science , physics , nuclear magnetic resonance , condensed matter physics , composite material , quantum mechanics , genetics , biology
Abstract Measuring internal induced electric fields in animals with a miniaturized probe involves a potential error related to the difference between the hole conductivity (σ h ) and the surrounding tissue conductivity (σ t ). Theory was developed to describe this phenomenon and checked by probe measurements in agar‐filled petri dishes. The value measured in the hole is 2σ t /(σ h + σ t ) times the actual field in the tissue. For example, a probe hole in muscle, which is filled with blood, could yield a measurement only about 22% of the true value in the muscle. This potential source of error can be mitigated to some extent by not actually cutting a hole, by using a low‐conductivity (e.g., 0.2 S/m) coupling medium in the hole, or by ensuring contact between the probe's electrodes and the tissue. © 1994 Wiley‐Liss, Inc.