Specific absorption rate distribution on a human head model from inductive power coils

We are interested in the amount of power that is absorbed by the eye and surrounding head tissue due to operation of inductive coils which are placed in proximity to the eye. These coils provide power to a retinal implant device wirelessly by means of electromagnetic induction. Using numerical simulation, we computed the specific absorption rate (SAR) due to the coils which are expected to deliver an average of 50 mW of power to the implanted device. By varying the distance of the coil from the eye and its operation frequency, we are able to find the dependence of SAR due to these parameters. From the result, we found that the maximum SAR value to be below 1 mW/kg. This is several orders of magnitude lower than the safety limits set by the Federal Communications Commission.

[1]  Shun Bai,et al.  Wireless technologies for closed-loop retinal prostheses , 2009, Journal of neural engineering.

[2]  G. Lazzi,et al.  Thermal effects of bioimplants , 2005, IEEE Engineering in Medicine and Biology Magazine.

[3]  Shun Bai,et al.  High Efficiency Double-Paired Inductive Coils for Wireless Powering of a Retinal Prosthesis , 2010 .

[4]  Shahriar Mirabbasi,et al.  Design and Optimization of Resonance-Based Efficient Wireless Power Delivery Systems for Biomedical Implants , 2011, IEEE Transactions on Biomedical Circuits and Systems.

[5]  C. Cacou.  Anthropometry of the head and face , 1995 .

[6]  Clive S. Boyd,et al.  High-Q flexible spiral inductive coils , 2010, 2010 Electromagnetic Compatibility Symposium - Melbourne.

[7]  Mohanasankar Sivaprakasam,et al.  Challenges in Realizing a Chronic High-Resolution Retinal Prosthesis , 2007 .

[8]  W. Ko,et al.  Design of radio-frequency powered coils for implant instruments , 1977, Medical and Biological Engineering and Computing.

[9]  P. J. Hoopes,et al.  Basic principles of thermal dosimetry and thermal thresholds for tissue damage from hyperthermia , 2003, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[10]  Robert Puers,et al.  Omnidirectional Inductive Powering for Biomedical Implants , 2008 .

[11]  R. Pethig,et al.  Dielectric properties of body tissues. , 1987, Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics.

[12]  Mani Soma,et al.  Radio-Frequency Coils in Implantable Devices: Misalignment Analysis and Design Procedure , 1987, IEEE Transactions on Biomedical Engineering.