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In Vitro Exposure Apparatus for ELF Magnetic Fields
01/12/2004

In Vitro Exposure Apparatus for ELF Magnetic Fields

Jürgen Schuderer, Walter Oesch, Norbert Felber and Niels Kuster, Bioelectromagnetics, Volume 25, Issue 8, pp. 582–591, December 2004.


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 <1 V/m, no recognizable temperature differences in the media for exposure or sham state, and vibrations of the mechanically decoupled dish holder <0.1 m/s2 (= 0.01 g), which is only twice the sham acceleration background level produced by the incubator and fan vibrations.