In this paper, a multi-band spiral-shaped implantable antenna for scalp implantation and leadless pacemaker systems is presented. The proposed antenna has the following operational bands: Medical Implanted Communication Service (402–405 MHz), Industrial, Scientific, and Medical (433.1–434.8 MHz and 2400–2483.5 MHz), and midfield (1520–1693 MHz). The recommended antenna system consists of two implantable devices, a flat-type scalp implantable device and a capsule-type leadless pacemaker. In each device the antenna is integrated with controlling electronic components and a battery. The proposed antenna has a compact size of 17.15 mm3 (7 mm × 6.5 mm × 0.377 mm). A significant size reduction for the antenna is achieved by using a spiral-shaped radiator with two symmetrical arms and introducing an open-end slot in the ground. The key features of the proposed antenna are its compact size, vialess ground plane, multi-bands, wide bandwidth and satisfactory gain values compared to other implantable antennas. The maximum realized gain values of the proposed structure are −30.5, −30, −22.6, and −18.2 dBi at 402, 433, 1600, and 2450 MHz, respectively. The design and analysis of the antenna is carried out with simulators, based on the finite element method and the finite difference time domain. The performance of the antenna is validated experimentally using a saline solution and minced pork muscles. Moreover, the specific absorption rate (SAR) distributions at all frequencies, induced by the implantable antenna are evaluated. In addition, a wireless communication link budget is calculated to specify the range for bio-telemetry at data rates of 7 and 100 kbps.

This paper presents a miniaturized triple band implantable antenna system for multiple biotelemetry applications, which operates at the Industrial, Scientific, and Medical (ISM) band (902–928 MHz, 2400–2483.5 MHz) and the midfield band (1824–1980 MHz). These bands are intended for the function of data telemetry, wireless power transfer, and power saving. The recommended antenna system is comprised of two implantable devices, a capsule type for deep tissue implantation and a flat type for skin implantation. The volume of these devices is 647 mm3 and 425.6 mm3, respectively. The compact size of the proposed antenna system is 21 mm3 (7 mm × 6 mm × 0.5 mm), which is the smallest size yet presented. The miniaturization is achieved by meandering the shape of the radiating patch, adding an open end ground slot, and introducing a shorting pin between ground plane and radiating patch. In the proposed antenna, simulated bandwidth is 8.7% and 7.3% at the ISM bands and 8.2% at the midfield band, and the measured bandwidth in a saline solution is 14.7% and 24.8% at the ISM bands and 13.1% at the midfield band. Finally, a link budget is calculated at different data rates to specify a range for data telemetry.

In this study, the first-ever dual-circular-polarized wideband conformal endoscopic antenna is designed at the medical implant communication service band (402 MHz) and industrial, scientific, and medical bands (915 MHz, and 2.4 GHz). The proposed antenna with a small footprint of 8 mm3 (32 mm × 10 mm × 0.025 mm) is printed on flexible polyamide and wrapped onto the inner wall of the capsule to spare the space for the capsule integrated components. For evaluation of the antennas performance within a full-package endoscopic device, a homogeneous muscle box and realistic Duke human phantoms were used. For measurement, the fabricated antenna is enclosed inside a 3D-printed capsule along with the endoscopic system, and the enclosed system is waterproofed. The S-parameters and radiation patterns are measured in a saline-filled American Society for Testing and Materials (ASTM) model and in a mincedpork phantom. The measured impedance bandwidths and gains at 402 MHz, 915 MHz, and 2.4 GHz are 236.2%, 104%, and 55.4%; and -29.71 dBi, -28.7 dBi, and -20.8 dBi, respectively. The measured axial-ratio bandwidths are 45.9% and 21.3% at 915 MHz and 2.4 GHz, respectively. Further, the link budget is numerically analyzed and measured via real-time telemetry using software-defined radios. The proposed antenna complies well with the human safety standards and satisfies the range and high data-rate requirements.

Advancement in the technology of leadless cardiac pacemakers (LCPs) has led to ultra-compact designs of implantable antennas. In this study, we developed a small-sized antenna for integration with an LCP that can be operated in the industrial, scientific, and medical (ISM) band of 2.4 GHz. The proposed antenna was constructed in a spiral shape to provide superior miniaturization, less sensitivity to body tissue variation, low specific absorption (SAR) values, and avoid fabrication complexities owing to its small size. The antenna with a footprint of 3 × 4 × 0.5 mm3 was constructed on a high dielectric material, namely Rogers RT/duroid 6010. To the best of our knowledge, this is the smallest footprint with enhanced performance when compared to previous reports related to implantable antennas. Additionally, the antenna was integrated with a 3D printed LCP having dummy electronics and experimentally validated in saline solution and minced pork. The antenna sustained good impedance matching at the ISM band with a measured bandwidth of 21.88% and 15.46% with the device and without the device, respectively. Owing to the smooth electric field (surface currents) over the patch, the antenna system had, respectively, 270.28 and 31.04 W/kg peak SAR for 1 and 10 g of tissues with a maximum peak gain of -25.95 dBi. We also discussed the effects of a coaxial cable and the antenna orientation on its performance. From the measured received signal strength, a stable biotelemetric link can be established between the implant and external controlling device up to a distance of 2 m.

In this study, a biotelemetry device for scalp implantation is proposed with an ultra-miniaturized and simple-structured implantable antenna that exhibits dual-band characteristics in the industrial, scientific, and medical bands (915 MHz and 2.45 GHz). The proposed system incorporates two batteries and microelectronic components in a total volume of 434.72 mm3. The recommended antenna has a reduced volume of 9.8 mm3 (7 mm × 7 mm × 0.2 mm), which is the smallest antenna presented so far. In homogeneous and heterogeneous environments, the designed antenna system has peak gain values of -28.04 and -28.94 dBi, respectively, at 915 MHz, and -23.01 and -23.06 dBi, respectively, at 2.45 GHz. For validation, the prototype of the antenna and corresponding system are immersed in a 3D head phantom (saline solution), and the measured results are found in close agreement with the simulation results. Additionally, the data communication range is analyzed through a link budget calculation at several data rates and an input power of -16 dBm. The radiation of the antenna system in the two principal planes (E and H) are similar to being omni-directional and directed away from the anatomical human body model as mandatory for the telemetry applications. Hence, the proposed antenna system can be employed in scalp implantation, especially for intracranial pressure monitoring.