Compacted Conformal Implantable Antenna With Multitasking Capabilities for Ingestible Capsule Endoscope
Muhammad Yousaf, Ismail Ben Mabrouk, Farooq Faisal, Muhammad Zada, Zubair Bashir, Adeel Akram, Mourad Nedil, Hyoungsuk Yoo
Abstract
This study presents a multi-band conformal antenna based endoscopic system for robust biotelemetry communications, which covers five important bands, including the MedRadio (401–406 MHz), Industrial, Scientific, and Medical (ISM) (433.1–434.8 MHz, 868–868.6 MHz, 902–928 MHz), and midfield (1200 MHz) bands. These bands are intended for functions such as biotelemetry, power saving, and wireless power transfer (WPT). The proposed antenna is printed on a flexible material Rogers ULTRALAM with a thickness of only 0.1 mm, which can be easily wrapped around the inner wall of a capsule. Owing to the insertion of the via and open-ended meandered slots in the radiator and in the ground plane, the footprints of the suggested antenna reduce considerably. In the flat form, the antenna is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$57~mm^{3}$ </tex-math></inline-formula> in volume, whereas in the wrapped form, it is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$48.98~mm^{3}$ </tex-math></inline-formula> in volume. In a homogeneous muscle phantom, the proposed conformal antenna shows a 27.46% wider bandwidth at 402 MHz,whereas it shows a 13.2% and 5.42% bandwidth at 915 MHz and 1200 MHz, respectively. Furthermore, the specific absorption rate investigation at three resonance frequencies in various implanted locations shows compliance with the IEEE guidelines, thereby guaranteeing human safety. For measurements, a 3D capsule with batteries and circuitry is devised using a 3D printer, and the simulation results are experimentally validated in a box containing minced pork. Finally, the robustness of the communication link is confirmed through the link budget analysis at 1 Mb/s. The conformal design concept, omni-directional radiations, and multi-band functionality with a wider bandwidth in the MedRadio band of the suggested antenna will enhance the diversity of the capsule endoscope and be a good addition to the field of biotelemetry.