PIERS 2023, Prague, Czech
July 3 - July 6, 2023 (Mon. - Thur.), Prague Congress Center
Patch-Type Electromagnetic Wave Focusing Metasurface for
Wireless Power Transfer in Bio-Implantable Devices
Wonwoo LEE, Semin Jo, and Hojin Lee
Abstract
With the advances in biomedical technologies, convenient, long-term operable, and
sustainable implantable devices are required to be used within the human body, including drug
delivery, stimulators, sensors, and post-stimulation monitoring. In general, batteries are used as
power sources in these implantable devices, but bioimplantable devices using batteries have
challenges in limited lifetime, bulky size, and need for replacement that essentially requires
surgical operations. In this regard, wireless power transfer systems (WPT) have been employed as
alternatives method to eliminate the use of battery and inevitable surgery for replacement. Recently,
WPT systems using metasurfaces exhibiting exotic electromagnetic (EM) characteristics were
introduced in bioimplantable devices to enhance the efficiency and to reduce the geometrical
dimension. Herein, we propose a patch-type metasurface that improves the power transmission to
the tissue by reducing the reflection loss of electromagnetic waves at the air–skin interface and
forming a focal point at a specific location. The subwavelength-thickness (< λ/10) metasurface is
introduced that focuses electromagnetic waves to a desired depth in multilayered biological tissues
to enhance the transferred power for implantable devices. The stable focusing performance is
demonstrated by confirming the robust focal point and field intensity profiles for varying incident
angles and polarization directions with enhanced field of approximately 11.1 dBmV at a depth of
10 mm in in-vitro environment. By applying the patch-type metasurface to an actual wireless
power transfer system, transmission coefficient is improved by 6.37 dB at a depth of 10 mm
compared with that of a system without the metasurface patch.
