Proposal of 28 GHz In Vitro Exposure System Based on Field Uniformity for Three‐Dimensional Cell Culture Experiments

Abstract

This paper proposes a novel in vitro exposure system operating at millimeter‐wave (mmWave) 28 GHz, one of the frequency bands under consideration for fifth generation (5G) communication. We employed the field uniformity concept along cross‐sectional observation planes at shorter distances from the radiation antenna for better efficiency and a small‐size system. A choke‐ring antenna was designed for this purpose in consideration of a wider beamwidth (BW) and a symmetric far‐field pattern across three principal planes. The permittivity of Dulbecco's modified Eagle's medium solution was measured to examine the specific absorption rate (SAR) of the skin cell layer inside a Petri dish model for a three‐dimensional (3D) cell culture in vitro experiment. The best deployment of Petri dishes, taking into account a geometrical field symmetry, was proposed. Local SAR values within the cell layer among the Petri dishes were determined with different polarization angles. It was determined that this polarization effect should be considered when the actual exposure and deployment were conducted. We finally proposed an in vitro exposure system based on the field uniformity including downward exposure from an antenna for 3D cell culture experiments. A small‐size chamber system was obtained, and the size was estimated using the planar near‐field chamber design rule. Bioelectromagnetics. 2019;40:445–457. © 2019 Bioelectromagnetics Society

Effects of Electromagnetic Waves with LTE and 5G Bandwidth on the Skin Pigmentation In Vitro

“…Here, using our LTE and 5G cell exposure systems (Schemes 1 and 2), we examined the effects of LTE and 5G EMFs on skin pigmentation in vitro [23]. Especially, the 5G in vitro "all-in-one" exposure system for 28 GHz frequency, which is one of the important millimeter-wave frequencies for 5G commercial services, has been developed [24,25]. Human and murine melanoma cell lines (MNT-1 and B16F10), human keratinocyte cell line (MNT-1-HaCaT) co-culture, and a 3D pigmented human epidermis model (MelanoDerm™, MatTek, Ashland, MA, USA) were employed to examine the pigmentary effects of LTE and 5G EMFs with the exposure time of EMF set to 4 h per day, which is known to be the upper bound of smartphone usage time per day [26].…”

Implementation of an in vitro exposure system for 28 GHz

“…The system requirements of an in vitro 28-GHz exposure system based on simulations [18] are summarized in Table 1. A plane wave impedance of 377 Ω should be realized for each vertical distance d less than the distance of the far-field region to obtain good uniformity and reduce the chamber size.…”

“…The symmetric broadbeam performance can be seen for all three principal planes. The desired 3-dB uniformity area of 80 mm × 80 mm, which corresponds to a symmetrical 2 × 2 deployment of four Petri dishes to suppress polarization effects [18], is fully accomplished over each vertical distance d as a result. Note that this 3-dB uniformity stems from the reasonable distributions of the PD over cultured cells for a practical experiment [13].…”

“…Saline solutions and Micropig Franz cell membranes (Medi Kinetics Co., Ltd.) were used as a practical model for the 3D cell culture experiments, which are usually composed of a culture medium and a reconstructed cell model [20]. The center-to-center distance between the dishes was 39 mm, in accordance with the exposure area [18]. Measurement areas were designated at all four cell surfaces in the inserts via the main SW.…”

“…Compared to other reported in vitro MMW exposure systems [12][13][14][15][16], little effort has been made to practically realize an in vitro experiment system for 5G MMW exposure. The entire system is based on field uniformity [18] to provide adequate exposure area for three-dimensional (3D) cell culture [19,20], which is more efficient in dealing with a shallow skin depth of approximately 1 mm at MMW frequencies [10]. A significant feature of the implemented system is its "all-in-one" characteristics, that is, every system component is incorporated into a single unit for a more accurate exposure experiment.…”