Multilayer Archimedean spiral antenna design for dual-band intra-arm implantable biotelemetric smart health care monitoring system covering MICS and ISM bands


UÇAR M. H. B. , Uras E.

FREQUENZ, 2022 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2022
  • Doi Number: 10.1515/freq-2021-0184
  • Title of Journal : FREQUENZ
  • Keywords: Archimedean spiral, biotelemetry, implant antenna, ISM-band, microstrip antennas, MICS-band, BODY

Abstract

In this paper, a novel multilayer microstrip implant antenna (MIA) design based on the Archimedean spiral (AS) radiator element is presented for dual-band biotelemetric health care monitoring system. The proposed AS-MIA design has a layered structure consists of the spiral antenna elements and superstrate, namely layer( #1 ), layer( #2 ) and layer( #3 ), respectively. While achieving the dual-band multi-layer implantable antenna design, firstly, each of the radiating elements in the respective layers is designed to cover separately in the desired bands, that is, layer(#1) and layer(#2) operate in the ISM (Industrial, Scientific, and Medical 2.4-2.48 GHz) and MICS (Medical Implant Communication Services 402-405 MHz) bands, respectively. Subsequently the ultimate multilayered AS-MIA design is formed by combining the individually designed layers. The compact implantable antenna has a dimension of r = 5 mm radius and h = 3.81 mm height, owning the electrically size of 0.067 lambda(0) and h = 0.051 lambda(0), respectively, where lambda(0) is free space wavelength at 402 MHz in MICS band. Since the AS-MIA is intended to be used in an intra-arm smart health system, the simulated radiation performances of the antenna in a created numerical arm phantom are presented in the article. Also note that numerical analysis of the implant antenna was carried out using CST MW studio simulator based on finite integral method. The prototype of the implantable antenna was fabricated using Rogers 3210 substrate with electrical permittivity of epsilon( r ) = 10.2. In-vitro return loss measurements were realized in skin mimicking gels, suggested in the literature. It was observed that in vitro measurement and simulation results were quite compatible with each other, except for some discrepancies due to the manufacturing and material tolerances during the preparation of the prototype antenna and skin mimicking gels. The proposed AS-MIA offers a dual-band operation with 15 and 16% S-11 bandwidth at each band of 402 MHz and 2.4 GHz respectively where |S-11| <= 10 dB criterion along with 50-omega system is considered. Also the proposed design can be a good candidate to be used in dual-band medical implant communication systems with its miniature size and reasonable radiation characteristics.