Myles Capstick, Yijian Gong, Boris Pasche, and Niels Kuster, Bioelectromagnetics, Volume 37, online March 31, 2016
An exposure system that addresses the difficulties that arise during exposure of small animals at low frequencies with high exposure levels is presented. The system, operating at 27 MHz and consisting of two identical transverse electromagnetic (TEM) cells for exposure and sham exposure of groups of 16 free-running mice housed in pairs within standard cages, is capable of exposure over extended daily periods with provision of food and water. The inclusion of theTEM cell in half-wavelength resonator increases the exposure by >50-fold compared to traditional TEM cell configurations. The system described allows both daily and weekly exposure schedules and supports blinded protocols with continuous wave (CW) and amplitude modulation (AM) signals with programmable modulation depths and frequencies. Electric field homogeneity across the TEM cell along a vertical plane orthogonal to the axis of the TEM line was within 3.3%, and within 3.1% along the horizontal plane. Accurate and comprehensive dosimetric assessments based on whole-body and organ-specific specific absorption rates (SAR) essential for in vivo bioelectromagnetic experiments that take into account various factors, e.g., mouse activities, close proximity, and field homogeneity, are presented. Average SAR levels are controllable in the range of 1 mW/kg – 2 W/kg, with expanded uncertainty (k = 2) of 1 dB and instantaneous variation (k = 1) of 4 dB.
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