A Compact Dual-Band Implantable Antenna for Wireless Biotelemetry in Arteriovenous Grafts

Arteriovenous grafts (AVGs) are indispensable life-saving implants for chronic kidney disease (CKD) patients undergoing hemodialysis (HD). However, AVGs will often fail due to postoperative complications, such as cellular accumulation termed restenosis, blood clots, and infections, which are dominant causes of morbidity and mortality. A new generation of HD implants equipped with biosensors and multiband antennas for wireless power and telemetry systems that can detect specific pathological parameters and report AVGs’ patency would be transformative for CKD. Our study proposes a compact dual-band implantable antenna for HD monitoring applications. It operates in 1.4 and 2.45 GHz for wireless power transfer and biotelemetry purposes. The miniaturized antenna with a current size of
$5\times 5\times0.635$
mm3 exhibits wide bandwidth (300 MHz at 1.4-GHz band and 380 MHz at 2.45-GHz band), along with good impedance matching at two resonance frequencies. In addition, simulations are performed separately in a three-layer homogenous phantom and a realistic human body model. Measurements of the proposed antenna are evaluated in minced pork. The measured results of the fabricated antenna prototype are closely harmonized with the simulation ones, and the effect of different proportions of fat tissue in pork mince was analyzed to verify the sensitivity of the antenna to the contacting medium. The specific absorption rate (SAR) and link budget calculation are also analyzed. Finally, the wireless biotelemetry function of the proposed antenna is realized and visualized by adopting a pair of nRF24L01 wireless transceivers, and sustainable and stable wireless data transmission characteristics are shown at a high data rate of 2 Mb/s with up to 20-cm transmission distance.