Ultraminiaturized Dual-Band Implantable Antenna for Wireless Capsule Endoscopy

This study introduces a small dual-band implantable antenna designed for wireless capsule endoscopy (WCE). This antenna operates in the Wireless Medical Telemetry Service (WMTS) 1.4 GHz as well as the Industrial, Scientific, and Medical (ISM) 2.45 GHz bands. The designed antenna achieves miniaturization by employing open-ended slots, shorting pins, and arc-shaped slots on the radiating patch. The final structure has a compact size of 8.2 x 8.2 x 0.635 mm(3). Homogeneous muscle and heterogeneous human phantoms are used to analyze the antenna's behavior. The measurements are conducted by implanting the WCE device within minced pork meat. Considering the capsule's deep location, the proposed antenna achieves gain values of -29.4 at 1.4 and -30.4 dBi at 2.45 GHz, respectively. The measured impedance bandwidths are 7.2% and 4.2% at 1.4 and 2.45 GHz, respectively. Results suggest that the proposed antenna can reliably establish wireless communication at distances greater than 10 m with a 10 dB margin for both frequencies. The 10-g specific absorption rate (SAR) values are 4.77 and 6.07 W/kg at 1.4 and 2.45 GHz, respectively.