University of Oulu

M. S. Zulkefli et al., "Experimental Wireless Link and SAR Assessments of an Implantable PIFA for Biotelemetry in the 2.45 GHz Band," in IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, vol. 7, no. 3, pp. 281-289, Sept. 2023, doi: 10.1109/JERM.2023.3294707.

Experimental wireless link and SAR assessments of an implantable PIFA for biotelemetry in the 2.45 GHz band

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Author: Zulkefli, Muhammad Solihin1; Zhang, Kai2; Särestöniemi, Mariella3;
Organizations: 1Faculty of Electronic Engineering and Technology, University Malaysia Perlis, Arau, Malaysia
2School of Information and Communications Engineering, Xi'an Jiaotong University, Xi'an, China
3Centre for Wireless Communications (CWC), University of Oulu, Oulu, Finland
4Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, U.K.
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 2.1 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2023
Publish Date: 2023-08-22


An experimental wireless link and specific absorption rate (SAR) assessment is presented in this work. A compact planar inverted-F antenna (PIFA) is designed and evaluated for biotelemetry application as an antenna at 2.45 GHz band. The proposed antenna provided a satisfactory bandwidth per unit volume using a two-layered stacked structure consisting of a high-frequency laminate and a low loss ceramic layer. The antenna was first co-designed inside several different types of phantom boxes to optimize its performance, considering computational resources. Next, a semisolid intestinal phantom model used in simulations were chosen to be fabricated for experimental evaluations. Evaluation results indicated a satisfactory antenna’s operation from 2.13 to 2.81 GHz (bandwidth of 27.8%), with realized gains of −26.49 dBi when implanted at 45 mm inside the phantom. Next, measurements were performed on the antenna’s communication link with a wearable antenna to study the effects its depth (from 10 to 45mm), indicating transmission coefficients of between −40 and −60 dB at 2.45 GHz. Finally, its SAR levels are evaluated experimentally using a commercial measurement system when implanted within the human tissue. Results indicated satisfactory level of 0.685 W/kg (averaged over 10 g of tissues) and is suitable for biotelemetry application.

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Series: IEEE journal of electromagnetics, RF and microwaves in medicine and biology
ISSN: 2469-7249
ISSN-E: 2469-7257
ISSN-L: 2469-7249
Volume: 7
Issue: 3
Pages: 281 - 289
DOI: 10.1109/JERM.2023.3294707
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: This work was supported in part by the Swiss State Secretariat for Education, Research and Innovation (SERI) Seed Funding, in part by the Fundamental Research Grant Scheme (FRGS) from the Ministry of Higher Education, Malaysia under Grant FRGS/1/2020/ICT09/UNIMAP/02/5, and in part by China Scholarship Council (CSC).
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