Mode Stirred Reverberation Chamber (Msrc): A Large and Efficient Tool to Lead High Frequency Bioelectromagnetic in Vitro Experimentation

Abstract

Abstract-An important aspect of the studies undertaken in bioelectromagnetism relates to the choice of exposure facility. The characteristics of a real electromagnetic environment are far more complex compared to the one plane wave irradiation set-up used in the majority of bioelectromagnetic studies. Moreover, biological requirements should represent the starting point in the design of an in vitro exposure system. Indeed it is important to avoid altering the electromagnetic properties of the exposure system in the presence of biological equipments. Related to these two essential points, this article contributes to show the advantages of a Mode Stirred Reverberation Chamber (MSRC) to guarantee a controlled electromagnetic environment around biological materials for in vitro experimentation. An example of irradiation of in vitro human skin cells cultures is considered to illustrate this paper. In order to show that the biological conditions and the physical requirements for in vitro experiments are checked, two aspects are described. Firstly we achieved the characterization of the electromagnetic field generated around the biological system (both equipments and cultures). Secondly the analysis of the Specific Absorption Rate (SAR) inside the biological medium was evaluated both numerically and experimentally. Initially, the statistical properties of fields inside the MSRC were checked with or without the biological devices in order to verify their electromagnetic transparency with respect to the reverberating properties of the electromagnetic environment (inside MSRC). We checked the good agreement of the experimental electromagnetic power distribution with the theoretical one.The computation of electromagnetic energy absorbed by biological medium (SAR) was based upon Finite Difference in Time Domain (FDTD) technique. A numerical analogy was achieved between the MSRC behavior and a free-space finite sum of random plane waves. Simulations are able to provide both an estimation of SAR distribution inside each biological culture dish and a computation of the coupling effects between dishes. Relying on the previous conclusions, temperature measurements were led to evaluate the experimental SAR levels and its time variations inside the MSRC. Two high-frequency (900 MHz) environments were considered: A 10 minutes exposure with field amplitude inside the biological incubator of 7.87 V/m and 30 minutes with 41 V/m (SAR ranged from 2.6 mW/kg to 73 mW/kg, mean values). Numerical and experimental results prove the ability of MSRC to provide a large and efficient tool to achieve bioelectromagnetic experiments at high frequencies.

Absorbing Cross Section in Reverberation Chamber: Experimental and Numerical Results

“…On the other hand, also the studies of human exposure to electromagnetic field take benefit from RC in order to reproduce real exposure conditions [19,20]. RCs are successfully used to characterize materials and structures from a shielding point of view, also considering composite materials for architectural shielding [21][22][23].…”

Accurate Modeling of the Microwave Treatment of Works of Art

“…Several models reproduce the electromagnetic field in a reverberation chamber equipped with a mechanical mode stirrer, and some numerical results are compared with experimental measurements with a good agreement. Mode Stirred Reverberation Chambers (MSRC) guarantee a controlled electromagnetic environment around biological materials for exposure to electromagnetic fields [16,17].…”

Performance of the Reflectivity Measurement in a Reverberation Chamber

“…Various applications have already been available [1], and others are being studied. In particular, applications for radiate power measurements are shown in [3]; applications for shielding effectiveness measurements are shown in [4][5][6][7][8][9][10][11][12][13]; applications for absorption measurements are shown in [14][15][16][17][18][19]; applications for radiation efficiency measurements of antennas are shown in [20][21][22]; studies for the testing of wireless devices by emulations of a Rician radio environment are shown in [23][24][25][26]. The reflectivity measurement of materials is certainly an innovative application of an RC.…”