# Low-Frequency Magnetic Field Exposure System for Cells Electromagnetic Biocompatibility Studies
## 6 Results and Discussion
In the time domain of the experiment, the provided exposure system offers an additional benefit. For example, in the previously used experimental set-up [53] with one exposed and one control sample, the time required to perform five experiments correctly was 128 h, including pre-cultivation. Using the developed exposure system presented within this article, the time required to perform the same number of experiments, including pre-cultivation, is reduced to 32 h, resulting in significant time savings and thus effectivity enhancement. It is also appropriate to point out the possible disadvantages of the proposed system. The proposed system is primarily intended for use in the area of low frequencies and low intensities of MF. The higher intensity MF could introduce a specific limitation to the presented system as the maximal current carrying capacity limits the coil design due to the copper wire. The solution that increases the MF in the sample area is to use a thicker wire and the Helmholtz configuration. It is questionable whether more accurate results can be reached using the multipurpose system (for low and high intensities) or a specific system designed directly for low and extremely low intensities. Due to the total cost of producing two coils and two SpS in the amount of 2153 \(\upcels\), it is more advantageous to use two different systems designed separately for low and extremely low intensities and the high intensities of the MF. As mentioned in Section 2, comparable systems for EMF irradiation are designed for irradiation of only one sample or multiple samples with a minimal volume using a microplate and do not consider the inhomogeneity of the B-field. Other systems offer possible advantages of lower costs in terms of materials use and power consumption. However, they cannot be compared in terms of homogeneity. Temperature changes are important experimental confounders in the research with yeast in general. Therefore, a stable and good controlled temperature is essential for the credible interpretation of results. To achieve minimum temperature fluctuation, a commercially available incubator is used. The incubator maintains a stable temperature of 30 \({}^{\circ}\)C. The temperature of the internal incubator environment (air temperature) is additionally monitored continuously during in vitro experiments by the temperature measurement system. The temperature measurement system consists of two temperature sensors, DS18B20, connected to the Arduino platform. The temperature is recorded on an SD card and shown on an OLED display every 10 min. Figure 11 shows the incubator air temperature course for eight hours lasting experiment; each point represents the average temperature from 12 experiments. The low temperature of 24 \({}^{\circ}\)C occurring at the start of each experiment is caused due to the opening of the incubator door and manipulation with samples. During the 8 h lasting experiment, the door remains closed. The temperature difference stabilizes after 4 h (\(\Delta\)T260) from the start of the experiment, where the temperature difference between control and exposed samples is less than 0.5 \({}^{\circ}\)C, and it is no longer increasing. The temperature of the YPD medium in exposed and control samples is measured before and after each experiment using the conductometer PC 70 Vio. The average YPD temperature difference between control and exposed samples A-E in 12 experiments before and after the experiment is shown in Figure 12.  
Figure 11: Temperature profile during the experiment, an average of 12 experiments. Figure 12: The average YPD temperature difference between control and exposed samples before and after the experiment. The average temperature difference between the exposed and control samples does not exceed 0.5 \({}^{\circ}\)C in both temperature sensors and conductometer. Achieved temperature differences are sufficient for the credible interpretation of yeast research results [54].