Redução de taxa de absorção específica em phantoms de tecidos humanos por meio de superfícies seletivas em frequência com substratos feitos de têxteis hospitalares

Abstract

This work proposes an integrated antenna with frequency selective surface (FSS) with textile substrate for applications in medical continuous monitoring systems with reduced specific absorption rate (SAR). The antenna and FSS were fabricated on cotton and polyester textile substrates, used in textile healthcare products, based on the technical standard ABNT NBR 13734:2016 - Textile healthcare products, for operation in the ISM 2.4 GHz frequency band. The system operates at a frequency of 2.4 GHz. Three textile materials with varying proportions of cotton and polyester were chosen to design the antennas and FSS. The electrical characterization of these materials was carried out. The antenna is designed for a filled ground plane and a rectangular patch fed by a microstrip line. The FSS was designed using square loops. The experimental operation of the frequency selective surfaces within the range of interest was observed through the transmission coefficient as a function of frequency. Phantoms were fabricated to emulate human tissues skin, fat, blood and muscle, and a thermal analysis was carried out to evaluate the impact of continuous exposure on signal transmission from the antenna integrated into the fabricated phantoms. The results demonstrate a reduction in SAR due to the effective rejection of the ISM band signal by the FSS of around 77.77% compared to the system with the active antenna without the presence of the FSS.