Biomedical applications and challenges of in-body implantable antenna for implantable medical devices: A review

The perpetual evolution of systems, materials, and processes has ushered in a new era of breakthroughs for implantable medical devices(IMDs), once hindered by technological bottlenecks. Such devices have captured the attention of the scientific and industrial community as a potential tool for biomedical telemetry, due to their capacity to offer incessant, real-time physiological data and electrotherapy through dynamic, non-intrusive measurements and stimulation. Among the implantable medical devices, due to implantable antenna receive and transmit signals from the human body to outside, as the irreplaceable component have been employed for various biomedical applications. With the dispersion and variability of human tissues and organs, the signal is heavily attenuated in vivo, and there are also safety and size limitations of the device. Therefore, implantable antennas still face many challenges and problems. To the best of our knowledge, in this review, the first summary of all current miniaturization techniques for implantable antennas, with an innovative and detailed analysis of the effects of electromagnetic waves on signal propagation in non-uniform media, are discussed, accompanied by recent solutions based on the challenges encountered. The latest fields of implantable device applications are exhibited, and the structural form and radiation characteristics of implantable antennas are analyzed. Finally, in light of the current developmental landscape, we present an original outlook on the future prospects and trends of IMDs, which assist designers to consider implantable antennas as an aid of ingesting implantable devices for the future biomedical field. We anticipate that the convergence of future multi-techniques will lead to brighter prospects.