Evaluation of SAR and Temperature Rise in Human Hand Due to Contact Current From 100 kHz to 100 MHz
Evaluation of SAR and Temperature Rise in Human Hand Due to Contact Current From 100 kHz to 100 MHz
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DOI：
10.1109/access.2020.3035815
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发表时间：
2020-01-01
期刊：
影响因子：
3.9
通讯作者：
Hirata, Akimasa
中科院分区：
文献类型：
--
作者：
Murakawa, Taiki;Diao, Yinliang;Hirata, Akimasa
保护人类免受射频辐射的国际准则/标准通过假设经典加热效应的最低阈值设定了限值。然而，没有计算研究报告，评估温度上升，由于接触电流。本文提出了一个特定的吸收率（SAR）和温度上升，由于触摸接触电流的频率范围为100 kHz至100 MHz的计算剂量学使用一个详细的数值模型的人手。从传统的4-Cole-Cole色散模型获得的组织介电特性经常被认为是在剂量学研究。然而，计算的电阻抗与实验结果的比较表明，在手指的皮下脂肪的导电性应高于4-科尔-科尔值-可能归因于胶原纤维。然后，我们提出了一组组织介电电导率估计从最近的测量结果的表皮，真皮和皮下组织的电导率。因此，计算的电阻抗表现出良好的协议与测量。此外，使用建议的组织电导率获得的SAR和温升低于使用4-Cole-Cole值获得的SAR和温升。因此，基于4-Cole-Cole弥散模型获得的SAR和温升可能被夸大。我们还观察到，在指导/限制水平下，由于接触电流引起的稳态最大温升相当于2.5 ℃，这是最大允许温升（5 ℃）除以降低系数2。
International guidelines/standards for the protection of humans from radiofrequency exposure have set a limit by assuming the lowest threshold for a classical heating effect, among other effects. However, no computational study has been reported that evaluates temperature rise due to contact currents. This paper presents the computational dosimetry of a specific absorption rate (SAR) and temperature rise due to touch contact currents in the frequency range 100 kHz to 100 MHz using a detailed numerical model of a human hand. Tissue dielectric properties obtained from a conventional 4-Cole-Cole dispersion model have often been considered in dosimetry studies. However, a comparison of the computed electrical impedance with experimental results suggests that the conductivity of the subcutaneous fat in the finger should be higher than the 4-Cole-Cole values-potentially attributable to collagen fibers. We then proposed a set of tissue dielectric conductivities estimated from recent measurement results of conductivities for the epidermis, dermis, and subcutaneous tissue. Consequently, the computed electrical impedances exhibited good agreement with the measured ones. In addition, the SAR and temperature rise obtained using the proposed tissue conductivities were lower than those obtained using 4-Cole-Cole values. Therefore, the SAR and temperature rise obtained based on the 4-Cole-Cole dispersion model may be overstated. We also observed that the steady-state maximum temperature rise due to the contact current at the guidance/limit level was equivalent to 2.5 degrees C, which is the maximum permissible temperature rise (5 degrees C) divided by a reduction factor of 2.