# The Biocompatibility of Wireless Power Charging System on Human Neural Cells
## 4 Discussion  
The use of various electrical devices in daily human life has grown rapidly. It is due to a technological progress in the last two decades. Wireless communication technologies, such as smartphones, have become a necessity for modern people. Nowadays, EMF generated by mobile cell phones, radio, satellites communication systems, Wi-Fi systems or TV increase the level of electromagnetic smog noticeably. Each person is potentially exposed to various sources of EMF at the same time. The International Agency for Research on Cancer (IARC) classifies the RF-EMF as Group 2B, it means possibly carcinogenic to human [28]. Moreover, it has been hypothesized that neurological problems could occur as a consequence of RF-EMF exposure due to the small distance of the cranial nervous system and the location where the smartphones are predominantly used. These neurological disorders include changes in sleep habits [29], headache [30], and changes in EEG [31; 32]. However, there are several studies indicating more harmful nonthermal effects on human health [33; 34; 35; 36; 37; 38]. The aim of our study was to analyze the biological effect of EMF, which is generated by a newly constructed prototype for a wireless power charging system. Neural cells are one of the most frequently exposed cells using the contactless charging system. In addition to that, neural cells are very sensitive to environmental pollution (\"electromagnetic smog\"), because they participate in the transmission of excitation within the nervous system and their regenerative ability is low. We used three different cell lines. One of them is healthy normal cells, the other two are cancer cell lines. We used the biological variety of cells to get more complex results about the effect of EMF on cellular level. We also investigated if our set of parameters for EMF generation could have a selective inhibition influence on cell growth of cancer cells while normal cells would be not affected. Human Astrocytes (HA) were used as a model to study the function of the central nervous system and interaction between neural cells. Astrocytes are glial cells found in the brain and spinal cord. They are responsible for maintaining, supporting and repairing nervous tissue. In laboratory, HA are used as model to study neurotoxicity, drug development and various neurological diseases (Parkinson's or Alzheimer's diseases) [39; 40]. The neuronal properties of SH-SYSY, human neuroblastoma cells, makes these types of cells as a valuable model to study various  
Figure 12: Fluorescent analysis of human neural cells (HA, T98G, SH-SYSY) after exposure to EMF (87 kHz, 1.5 kW for 30 min) followed by 44 h regeneration. Cytoskeleton of cells was visualized by Phalloidin dye (green) and nuclei were stained by DAPI (blue). Representative photomicrographs were taken by WiScan® Hermes System at magnification 100\(\times\). pathological processes and mechanisms at molecular and morphological level [41]. The last one, T98G cells are derived from human glioblastoma multiform tumors. This cell line is used as a model for testing drug cytotoxicity and new drug development, which can be applied for brain cancer research [42; 43]. WHO defined the range from 300 Hz to 1 MHz as IF-EMF as a nonionizing radiation [44]. We applied 87 kHz during all experiments, which is defined within allowed operational range by relevant normative ICNIRP 2010. The Amplitude/Intensity of exposure field was in the range of 0.3-1.2 mT and exposure time was 30 min. These experimental values were set based on the maximal range limits of the constructed prototype along with the evident proof of the impact of EMF generated by the WPT system on human cells. The magnetic flux density, which was used in present work, is approximately 11-44 times higher comparing to reference level (27 \(\upmu\)T), which is recommended by ICNIRP guidelines [17]. We analyzed cell morphology, viability and cytoskeletal integrity in three cell lines in exposed cells comparing to unexposed control cells.