In vitro exposure apparatus for ELF magnetic fields

Abstract

For in vitro studies on the effect of extremely low frequency (ELF) magnetic field exposures in different laboratories, a programmable, high precision exposure system enabling blinded exposures has been developed and fully characterized. It is based on two shielded 4 coil systems that fit inside a commercial incubator. The volume of uniform B field exposure with 1% field tolerance is 50% larger compared to a Merrit 4 coil system with the same coil volume. The uncertainties for the applied magnetic fields have been specified to be less than 4%. The computer controlled apparatus allows signal waveforms that are composed of several harmonics, blind protocols, monitoring of exposure and environmental conditions and the application of B fields up to 3.6 mT root‐mean‐square amplitude. Sources of artifacts have been characterized: sham isolation >43 dB, parasitic incident E fields 2 (= 0.01 g), which is only twice the sham acceleration background level produced by the incubator and fan vibrations. Bioelectromagnetics 25:582–591, 2004.