Development of a higher power intermediate-frequency magnetic field exposure system for in vitro studies

In a previous article we developed an in vitro 23 kHz magnetic field (MF) exposure system that generated an MF of 532 microT(rms). Using this system, the biological effects of 23 kHz MFs on cell functions have been reported. To further clarify the biological effect of intermediate-frequency (IF) MFs and investigate the dose-response relationship in cell lines, an exposure system that generates stronger MFs is required. To meet this requirement, we developed a 6.25 mT(rms) MF exposure system for in vitro study. This level is 1000 times the reference level for the general public in the ICNIRP guidelines. This system provides an MF of 6.25 mT(rms) at 23 kHz with a uniformity within +/-5%. To verify that in vitro experimental conditions are maintained, we examined the temperature, environmental MF, and MF leakage for a sham exposure system. In addition, we examined the harmonics, coil shape, and heat generated in the medium by the high-strength MF. As a result, it was confirmed that this system can be used to evaluate the biological effects of IF MFs. This article presents the design and successful construction of the in vitro exposure system.