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Addition of magnetic field capability to existing extremely‐low‐frequency electric field exposure systems
Author(s) -
Miller D. L.,
Miller M. C.,
Kaune W. T.
Publication year - 1989
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.2250100109
Subject(s) - electric field , transformer , magnetic field , nuclear magnetic resonance , materials science , extremely low frequency , voltage , electrical engineering , in vivo , acoustics , physics , biomedical engineering , engineering , biology , quantum mechanics , microbiology and biotechnology
Magnetic field systems were added to existing electric field exposure apparatuses for exposing cell suspensions in vitro and small animals in vivo. Two horizontally oriented, rectangular coils, stacked one directly above the other, have opposite electric currents. This configuration minimizes leakage fields and allows sham‐ and field‐exposure systems to be placed in the same room or incubator. For the in vitro system, copper plates formed the loop‐pair, with up to 900 A supplied by a 180:1 transformer. Electric fields were supplied via electrodes at the ends of cell‐culture tubes, eight of which can be accommodated by each exposure system. Two complete systems are situated in an incubator to allow simultaneous sham and field exposure up to 1 mT. For the in vivo system, four pairs of 0.8 × 2.7‐m coils made of copper bus bar are employed. This arrangement is energized from the power grid via a 30:1 transformer; horizontal magnetic flux densities up to 1 mT can be generated. Pairs of electrode plates spaced 30.5 cm apart provide electric field exposure of up to 130 kV/m. Four systems with a capacity of 48 rats each are located in one room. For both the in vitro and in vivo systems, magnetic exposure fields are uniform to within ± 2.5%, and sham levels are at least 2,500‐fold lower than exposure levels. Potential confounding factors, such as heating and vibration, were examined and found to be minimal.