# Low-Frequency Magnetic Field Exposure System for Cells Electromagnetic Biocompatibility Studies
## 5 Cell Electromagnetic Biocompatibility Experiment  
To examine the effect of LF MF on cells and verify the functionality of the proposed exposure system, 12 paired experiments are performed. The biological material used in the experiment is a pure strain, BY4741 yeast cells Saccharomyces cerevisiae. The yeast cells are obtained from the Slovak Academy of Science in Bratislava and refrigerated at 4 C in a Petri dish. The theoretical basis of the experiment comes from [PERSON]'s IPR theory. The principle is in applying the MF generated by a parallel combination of static \(B_{\text{DC}}\) and time-varying \(B_{\text{AC}}\) MF. The theory of IPR suggests the nonthermal effect of MF on ions in living cells such that a protein-bound ion of mass \(m\) and charge \(q\) can be considered as a harmonic oscillator [12]. The correct application of the theory presupposes the application of time-varying MF with a frequency corresponding to the cyclotron frequency of the target bound ion, calculated according to the formula:  
\[f=\frac{1}{n}\frac{1}{2\pi}\frac{q}{m}B_{\text{DC}} \tag{3}\]  
Figure 8: The comparison of simulated values of B-field in CST Studio Suite and measured values of B-field obtained by Narda NBM-550 in exposure coil. Figure 9: The percentage difference between simulated and measured values of B-field in exposure coil. where \(q\) is the electric charge of the target ion, \(m\) is the molecular mass of the target ion, and \(B_{\rm DC}\) is the value of static magnetic flux density--the geomagnetic field in this case. The target is calcium ion \({}^{40}\)Ca\({}^{2+}\) with a cyclotron frequency of 29.89 Hz. According to the IPR, the maximal biological effect should be reached at the \(B_{\rm AC}/B_{\rm DC}\) ratio of 1.8. For the earth's magnetic field value of 39 \(\mu\)T measured at the location of the experiment's realization, the corresponding value of \(B_{\rm AC}\) is 70.2 \(\mu\)T to maintain the ratio. The exposure coil is powered by an arbitrary wave generator RIGOL DG4162; the signal is amplified by a HUBERT KEYSIGHT Infnii Vision MSO-X 3012A linear amplifier. The driving current is controlled by a digital multimeter Agilent 34401A. The exposure coil is powered by \(I=79.5\) mA (time course of sine shape, RMS), \(f=29.89\) Hz. The multimeter is connected for the whole experiment duration to monitor the value of the supply current continuously. The control coil is without a power supply, and it is shielded. The control coil represents the state without intervention, and its aim is to show the difference in the results between the natural process of multiplication and the growth of yeasts affected by the MF. The YPD medium is used in the experiment; the solution consists of 95% distilled water, 2% peptone, 2% dextrose, 1% yeast extract. After the medium is prepared, a 24 h pre-cultivation period is followed, starting with the inoculation of yeast cells into a flask with 20 mL of prepared YPD. The yeast medium is placed on a shaker and cultured for 24 h at 180 rpm at an ambient room temperature of 23 \({}^{\circ}\)C. Pre-cultured yeast solution with a volume of 0.05 mL is pipetted into each of ten prepared Erlenmeyer flasks, 5 control, and 5 exposed samples containing 25 mL of medium. The flasks are closed with cotton-wood plugs to ensure air access. The samples containing cultured cells in the YPD medium are placed into a coil cavity and then moved into the incubator. The incubator ensures the maintenance of a stable temperature of 30 \({}^{\circ}\)C during the whole experiment. The temperature is continuously measured in both cavities of the incubator using temperature sensors D18B20. The time of exposure to the MF is 8 h.  
To quantify the effect of applied MF, the numbers of cells in exposed vs control samples are compared. Cells are counted before and after each experiment in each sample using the Burker chamber. The cells are photographed using Axiocam ERc 5 s in an inverted microscope Zeiss Primovert.