ELF Magnetic Field Exposure System for In Vitro Studies Based on Lee‐Whiting Coils

In order to run a series of in vitro studies on the effect of extremely low‐frequency magnetic fields on cell cultures, developing and characterizing an appropriate exposure system is required. The present design is based on a two‐shielded Lee‐Whiting coils system. The circular design was chosen because its axial symmetry allowed for both reducing simulation unknowns and measurement points during the characterization, and additionally made the machining of the parts easier. The system can generate magnetic flux densities (B fields) up to 1 mT root‐mean‐square amplitude (rms) with no active cooling system in the incubator, and up to 3 mTrms with it. The double‐wrapped windings with twisted pairs allow for the use of each set of coils either as exposure or control with no detectable parasitic B field in the control. The artifacts have also been analyzed; the B field in the center of the sham control chamber is about 1 µTrms for a maximum of 3 mTrms in the exposure chamber, the parasitic incident electric fields are less than 1 V/m, the temperature difference between sham and exposure chamber is less than or equal to 0.2 °C, and the typical vibration difference between sham and exposure is less than 0.1 m/s2. © 2020 Bioelectromagnetics Society.