A Miniaturized Novel-Shape Dual-Band Antenna for Implantable Applications

Abstract

In this paper, a miniaturized novel-shape dual-band implantable antenna operating in the industrial, scientific, and medical bands (902-928 MHz and 2.4-2.4835 GHz) is developed for battery-powered implants. The Rogers ULTRALAM (epsilon(r) = 2.9 and tan delta = 0.0025) liquid crystalline polymer material with 0.1 mm thickness is used as both the substrate and superstrate. By employing the shorting strategy, a flower-shape radiating patch, and open-ended slots in the ground plane, the total volume of the proposed antenna is confined to 7 x 7.2 x 0.2 mm(3). In a homogeneous skin phantom, the presented antenna has a maximum gain of -28.44 and -25.65 dBi at 928 MHz and 2.45 GHz, respectively. The calculated maximum specific absorption rate values are in the safe limit and satisfy the IEEE C95.1-1999 and C95.1-2005 safety guidelines. The design, optimization, and analysis of the suggested antenna are performed using the finite difference time-domain- and finite-element method-based simulators. The results suggest that the flower-shape antenna exhibits fairly omnidirectional radiation patterns; therefore, it can be used for gastro applications and skin implantations. Through wireless communication link, we validated that at both frequencies (928 MHz and 2.45 GHz), 7 Kb/s and 78 Mb/s of data can be transmitted easily over more than 6 and 1.5 m, respectively. To verify the validity of the design and simulation results, measurements are performed by substituting the fabricated prototype in the American Society for Testing Materials and head phantoms containing saline solution. The proposed flower-shape antenna shows salient performance parameters compared with the recently proposed antennas.