Ultra-Miniaturized Implantable Antenna Enabling Multiband Operation for Diverse Industrial IoMT Devices

Compact implantable medical devices (IMDs) require miniaturized and multiband antennas to efficiently navigate space limitations and diverse frequency demands in biomedical applications. This article proposes an ultra-miniaturized implantable antenna featuring the smallest footprint with a volume of 0.7 mm3 and exhibits quad-band characteristics: telemetry at 915 MHz, wireless power transfer at midfield bands of 1450 and 1900 MHz, and control signaling at 2450 MHz. Extensive simulation analyses were conducted for the antenna alone and integrated antenna systems to realize the versatility of the proposed antenna. For validation, measurements were performed in saline-filled realistic head and American Society for Testing and Materials (ASTMs) phantoms. Good agreement between the simulation and measured results was observed. The antenna showed stable performance in all scenarios with a measured -10 dB bandwidth of 136, 122, 108, and 134 MHz at 915, 1450, 1900, and 2450 MHz, respectively. Moreover, the antenna exhibited satisfactory measured gain values of -27.45, -23.25, -23.14, and -22.48 dBi at the respective frequency bands. Finally, the implementation of the wireless biotelemetry feature of the proposed antenna system was achieved and demonstrated through the utilization of a pair of software-defined radios (SDRs). Sustainable and stable wireless data transmission characteristics were shown at transmission distances of up to 2.5 m. With its remarkable features, the proposed antenna addresses the critical need for efficient communication in the Industrial Internet of Medical Things (IIoMT) devices, enabling telemetry, wireless power transfer, and control signaling in biomedical applications with limited space and diverse frequency demands.