Title:	Electromagnetic radiation efficiency of body-implanted devices
Authors:	Nikolayev, Denys Zhadobov, Maxim Karban, Pavel Sauleau, Ronan
Citation:	NIKOLAYEV, D., ZHADOBOV, M., KARBAN, P., SAULEAU, R. Electromagnetic radiation efficiency of body-implanted devices. Physical Review Applied, 2018, roč. 9, č. 2, s. 1-12. ISSN 2331-7019.
Issue Date:	2018
Publisher:	American Physical Society
Document type:	článek article
URI:	2-s2.0-85043480902 http://hdl.handle.net/11025/30942
ISSN:	2331-7019
Keywords in different language:	dielectric-properties;biological tissues;frequency-range;antennas;ghz
Abstract in different language:	Autonomous wireless body-implanted devices for biotelemetry, telemedicine, and neural interfacing constitute an emerging technology providing powerful capabilities for medicine and clinical research. We study the through-tissue electromagnetic propagation mechanisms, derive the optimal frequency range, and obtain the maximum achievable efficiency for radiative energy transfer from inside a body to free space. We analyze how polarization affects the efficiency by exciting TM and TE modes using a magnetic dipole and a magnetic current source, respectively. Four problem formulations are considered with increasing complexity and realism of anatomy. The results indicate that the optimal operating frequency f for deep implantation (with a depth d3 cm) lies in the (108-109)-Hz range and can be approximated as f=2.2×107/d. For a subcutaneous case (d3 cm), the surface-wave-induced interference is significant: within the range of peak radiation efficiency (about 2×108 to 3×109 Hz), the max-to-min ratio can reach a value of 6.5. For the studied frequency range, 80%-99% of radiation efficiency is lost due to the tissue-air wave-impedance mismatch. Parallel polarization reduces the losses by a few percent; this effect is inversely proportional to the frequency and depth. Considering the implantation depth, the operating frequency, the polarization, and the directivity, we show that about an order-of-magnitude efficiency improvement is achievable compared to existing devices.
Rights:	Plný text je přístupný v rámci univerzity přihlášeným uživatelům. © American Physical Society
Appears in Collections:	Články / Articles (KTE) Články / Articles (RICE) OBD

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