Conductivity differences distort probe measurements of magnetically induced electric fields.
Measuring internal induced electric fields in animals with a miniaturized probe involves a potential error related to the difference between the hole conductivity (sigma h) and the surrounding tissue conductivity (sigma 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 2 sigma t/(sigma h + sigma 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.
Miller
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DL
Battelle Pacific Northwest Laboratory, Richland, Washington 99352.
D000362:Agar; D000818:Animals; D001769:Blood; D002138:Calibration; D004553:Electric Conductivity; D004560:Electricity; D004574:Electromagnetic Fields; D004581:Electronics / Q000295:instrumentation*; D007552:Isotonic Solutions; D008280:Magnetics; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000502:physiology; D012965:Sodium Chloride
D007552:Isotonic Solutions; D012965:Sodium Chloride; D000362:Agar