A Novel Broadband Dual-Frequency Circularly Polarized Implantable Antenna Empowering Future Intelligent Healthcare

Implantable medical devices (IMDs) have captured the attention of the scientific and industrial community due to their capacity to offer incessant, real-time physiological data for biomedical telemetry and electrotherapy through dynamic, accurate measurements, and stimulation. As the "eyes" of IMDs, multifunctional implantable antennas demand thorough research and design. A compact dual-band circularly polarized (CP) antenna system working at 1.4 -2.45 GHz, at wireless medical telemetry service (WMTS) band and industrial, scientific, and medical (ISM) band, is developed in this communication. By incorporating the technique of loading symmetric meandering slots and short-pins, the dimensions of the entire antenna are reduced to 8.8\times 8.8\times 0.508 mm3. Simultaneously, based on the analysis of the current vectors and their superposition across various sections, it is demonstrated that the antenna exhibits right-hand circular polarization (RHCP) characteristics. To consider a practical operating scenario, the antenna was integrated with a battery and controlling electronics of a biocompatible shell. In the heterogeneous phantom, the proposed antenna showed a higher gain of −23.4, and −16 dBi at 1.4 GHz, and 2.45 GHz, respectively. This study represents the initial validation of the influence of diverse body types (varying fat content) on the frequency shift of the antenna. Additionally, we established the biological communication system of information through IMDs by employing a dual-band CP implantable antenna. To assess safety, the established invasive medical devices (IMDs) demonstrate in simulation results that the maximum specific absorption rate (SAR) value complies with the safety guidelines outlined by the IEEE standard.