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Bio-Heat and Mass Transfer

Specific Absorption Rate and Temperature Increase in Human Eye Subjected to Electromagnetic Fields at 900 MHz

[+] Author and Article Information
Teerapot Wessapan

Research Center of Microwave Utilization in Engineering (R.C.M.E.), Department of Mechanical Engineering, Faculty of Engineering,  Thammasat University, Rangsit Campus, Pathumthani 12120, Thailandratphadu@engr.tu.ac.th

Phadungsak Rattanadecho1

Research Center of Microwave Utilization in Engineering (R.C.M.E.), Department of Mechanical Engineering, Faculty of Engineering,  Thammasat University, Rangsit Campus, Pathumthani 12120, Thailandratphadu@engr.tu.ac.th

1

Corresponding author.

J. Heat Transfer 134(9), 091101 (Jul 09, 2012) (11 pages) doi:10.1115/1.4006243 History: Received July 28, 2011; Revised February 14, 2012; Published July 09, 2012; Online July 09, 2012

Human eye is one of the most sensitive parts of the entire human body when exposed to electromagnetic fields. These electromagnetic fields interact with the human eye and may lead to cause a variety of ocular effects from high intensity radiation. However, the resulting thermo-physiologic response of the human eye to electromagnetic fields is not well understood. In order to gain insight into the phenomena occurring within the human eye with temperature distribution induced by electromagnetic fields, a detailed knowledge of absorbed power distribution as well as temperature distribution is necessary. This study presents a numerical analysis of specific absorption rate (SAR) and heat transfer in the heterogeneous human eye model exposed to electromagnetic fields. In the heterogeneous human eye model, the effect of power density on specific absorption rate and temperature distribution within the human eye is systematically investigated. In particular, the results calculated from a developed heat transfer model, considered natural convection and porous media theory, are compared with the results obtained from a conventional heat transfer model (based on conduction heat transfer). In all cases, the temperatures obtained from the developed heat transfer model have a lower temperature gradient than that of the conventional heat transfer model. The specific absorption rate and the temperature distribution in various parts of the human eye during exposure to electromagnetic fields at 900 MHz, obtained by numerical solution of electromagnetic wave propagation and heat transfer equation, are also presented. The results show that the developed heat transfer model, which is the more accurate way to determine the temperature increase in the human eye due to electromagnetic energy absorption from electromagnetic field exposure.

Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Electromagnetic fields from an electromagnetic radiation device

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Figure 2

Human eye vertical cross section

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Figure 3

Boundary condition for analysis of electromagnetic wave propagation and heat transfer

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Figure 4

A two-dimensional finite element mesh of human eye model

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Figure 5

Grid convergence curve of the 2D model

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Figure 6

Comparison of the calculated temperature distribution to the temperature distribution obtained by Shafahi and Vafai, and the Lagendijk’s experimental data; ham  = 20 W/m2 K and Tam  = 25 °C

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Figure 7

Electric field distribution (V/m) in human eye exposed to the electromagnetic frequency of 900 MHz at the power densities of (a) 5 mW/cm2 , (b) 10 mW/cm2 , (c) 50 mW/cm2 , and (d) 100 mW/cm2

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Figure 8

SAR distribution (W/kg) in human eye exposed to the electromagnetic frequency of 900 MHz at the power densities of (a) 5 mW/cm2 , (b) 10 mW/cm2 , (c) 50 mW/cm2 , and (d) 100 mW/cm2

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Figure 9

The temperature distribution in human eye at various time exposed to the electromagnetic frequency of 900 MHz at the power density of 100 mW/cm2 calculated using (a) the conventional heat transfer model (b) the developed heat transfer model

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Figure 10

The extrusion line in the human eye where the temperature distribution is considered

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Figure 11

Temperature increase versus papillary axis of human eye exposed to the electromagnetic frequency of 900 MHz at various times

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Figure 12

The velocity distribution inside the anterior chamber in human eye when exposed to the electromagnetic frequency of 900 MHz

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Figure 13

The temperature distribution in human eye exposed to the electromagnetic frequency of 900 MHz at various power densities calculated using (a) the conventional heat transfer model (b) the developed heat transfer model

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Figure 14

The velocity distribution inside the anterior chamber in human eye exposed to the electromagnetic frequency of 900 MHz at the power densities of (a) 5 mW/cm2 , (b) 10 mW/cm2 , (c) 50 mW/cm2 , and (d) 100 mW/cm2

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Figure 15

Steady state temperature increases versus papillary axis of human eye exposed to the electromagnetic frequency of 900 MHz at various power densities

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