volume | PIER Journals

Abstract

Temperature increase analysis has been performed with consideration to the anatomical model of the human head exposed to a cellular phone operating at 900 MHz. Four different numerical methods, in particular an implicit method based on the Alternating Direction Implicit technique (ADI), were applied to solve the Bio-Heat Equation (BHE), their advantages and limitations were compared using a canonical case. The tests performed on the latest have shown that the implicit approach is well adapted to solve this type of equations. The rise of temperature in the human head exposed to the RF emission of a mobile phone with a radiated power of 250 mW at 900 MHz was analyzed. In addition the influence of the presence of the telephone kit close to the head was discussed. The influence of different thermal parameters such as the thermal conductivity and the blood perfusion coefficient on the rise of temperature has been analyzed. The simulation carried out showed that the maximum temperature increase in the internal tissues linked to SAR deposition does not exceed 0.1ºC. We recorded a temperature difference of 1.6ºC in the skin due to the presence of a switched off cellular phone, which has been confirmed by the experimental measurements performed.

1. ICNIRP Guidelines, ``Guidelines for limiting exposure to time-varying electric[#COMMA] magnetic[#COMMA], "Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields (up to 300 GHz)," Health Phys., Vol. 74, No. 4, 494-522, 1998.

2. IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz, 3 kHz to 300 GHz, 1-1991, IEEE standard C95.1-1991, 1992.

3. Gandhi, O. P., Q.-X. Li, and G. Kang, "Temperature rise for the human head for cellular telephones and for peak SARs prescribed in safety guidelines," IEEE Trans. Microwave Theory Tech., Vol. 49, No. 9, 2001.

4. Bernardi, P., M. Cavagnaro, S. Pisa, and E. Piuzzi, "SAR distribution and temperature increase in an anatomical model of the human eye exposed to the field radiated by the user antenna in a wireless LAN," IEEE Trans. Microwave Theory Tech., Vol. 46, No. 12, 1998.

5. Wiart, J. and R. Mittra, "Calculation of the power absorbed by tissues in case of hand set mobile antenna close to biological tissue," Proc. IEEE Symp. Antennas Propagat., No. 7, 1104-1107, 1996.

6. Bernardi, P., M. Cavagnaro, S. Pisa, and E. Piuzzi, "Power absorption and temperature elevations induced in the human head by a dual-band monopole-helix antenna phone," IEEE Trans. Microwave Theory Tech., Vol. 49, No. 12, 2001.

7. Hirata, A., M. Morita, and T. Shiozawa, "Temperature increase in the human head due to a dipole antenna at microwave frequencies," IEEE Trans. EMC, Vol. 45, No. 1, 2003.

8. Bernardi, P., M. Cavagnaro, S. Pisa, and E. Piuzzi, "Specific absorption rate and temperature increases in the head of a cellular-phone user," IEEE Trans. Microwave Theory Tech., Vol. 48, No. 7, 2000.

9. Taflove, A., Computational Electrodynamics: The Finite-Difference Time-Domain Method, Artech House, 1995.

10. Euvrard, D., "Résolution numérique des équations aux dérivées partiaelles," collection Masson, 58-61, 1994.

11. Brian, P. L. T., "A finite-difference method of high-order accuracy for the solution of three-dimensional transient heat conduction problem," Amer. Inst. Chem. Eng. J., Vol. 7, No. 3, 367-370, 1961.

12. Van Leeuwen, G. M. J., J. J. W. Lagendijk, B. J. A. M. Van Leersum, A. P. M. Zwamborm, S. N. Hornsleth, and A. N. T. J. Kotte, "Calculation of change in brain temperatures due to exposure to a mobile phone," Phys. Med. Bio., Vol. 44, 0031-9155, 1999.
doi:10.1088/0031-9155/44/3/006

13. CENELEC, European standard EN 50360 & EN 50361., European standard EN 50360 & EN 50361. , 5036.

14. Bronzino, J. D., Biomedical Engineering Handbook, Vol. 1, Vol. 1, 1999.

15. Gabriel, C., "Compilation of the dielectric properties of body tissues at RF and microwave frequencies," Occupational and Environmental Health Directorate, 1996-0037, 1996.

16. Ozisik, M. N., Finite Difference Methods in Heat Transfer, 1994., 1994.

17. Chebolu, S. R. S., "Efficient modeling of passive electronic devices using the finite difference time domain method," Thesis, 1996.

18. Chatterjee, I. and O. P. Gandhi, "An inhomogeneous thermal block model of man for the electromagnetic environment," IEEE Trans. Biomed. Eng., Vol. BME-30, No. 11, 1983.

19. Wang, J. and O. Fujiwara, "FDTD computation of temperature rise in the human head for portable telephone," IEEE Trans. Microwave Theory Tech., Vol. 47, No. 8, 1999.

20. Press, W. H., B. P. Flannery, S. A. Teukolsky, and W. T. Vetterling, Numerical Recipes in C, Cambridge University, 1988.

21. Yee, K. S., "Numerical solution of initial boundary value problems involving Maxwell's equations in isotropic media," IEEE Trans. Antennas and Propagation, Vol. 14, No. 3, 302-307, 1966.
doi:10.1109/TAP.1966.1138693

22. Burkhardt, M., K. Pokovic, M. Gnos, T. Schmid, and N. Kuster, "Numerical and experimental dosimetry of Petri dish exposure setups," Journal of Bioelectromagnetics Society, Vol. 17, 483-493, 1996.
doi:10.1002/(SICI)1521-186X(1996)17:6<483::AID-BEM8>3.0.CO;2-#

23. Laval, L., Ph. Leveque, and B. Jecko, "A new in vitro exposure device for the mobile frequency of 900 MHz," Journal of Bioelectromagnetics Society, Vol. 21, 255-263, 2000.
doi:10.1002/(SICI)1521-186X(200005)21:4<255::AID-BEM2>3.0.CO;2-4

24. Watanabe, S., M. Taki, and O. Fujiwara, "Characteristics of the SAR distribution in a head exposed to electromagnetic fields radiated by a hand-held portable radio," IEEE Trans. Microwave Theory Tech., Vol. 44, 1874-1883, 1996.
doi:10.1109/22.539946

25. Gedney, S. D., "An anisotropy perfectly matched layer absorbing media for the truncation of FDTD lattices," IEEE Trans. Antennas and Propagation, Vol. 44, 1630-1639, 1996.
doi:10.1109/8.546249

26. Berenger, J. P., "A perfectly matched layer for the absorption of electromagnetic waves," J. Computational Physics, Vol. 114, No. 2, 195-200, 1994.
doi:10.1006/jcph.1994.1159

27. Wang, T.-Y. and C. C.-P. Chen, "3-D thermal-ADI: A linear-time chip level transient thermal simulator," IEEE Trans. on Computer-Aided Design of Integrated Circuits and Systems, Vol. 21, No. 12, 1434-1445, 2002.
doi:10.1109/TCAD.2002.804385

28. Bernardi, P., M. Cavagnaro, S. Pisa, and E. Piuzzi, "Specificabsorptionrateandtemperatureelevationinasubjectexposedinthefarfieldofradio-frequencysourceoperatinginthe10-900MHzrange," IEEE Trans. On Biomedical Eng., Vol. 50, No. 3, 10-900, 2003.

Dr. Ahmed Ibrahiem

Dr. Christian Dale

Dr. Walid Tabbara

Dr. Joe Wiart