Search

In this study, an ultraminiaturized implantable antenna is developed for biotelemetry applications. It has triple-band characteristics in the industrial, scientific, and medical (ISM) bands of 902–928 MHz for data telemetry and 2400–2483.5 MHz for power-saving applications and midfield band (1824–1980 MHz) for wireless power transfer simultaneously. The size of the proposed antenna is 0.068 $\lambda _{g}\,\,\times0.048\,\,\lambda _{g}\,\,\times0.0036\,\,\lambda _{g}$ and it is the smallest size of any triple-band implantable antenna ever devised without using shortening vias. Such a compact size is achieved by meandering the shape of the radiating patch and adding open-ended ground slots. Unlike most miniaturized implantable antennas reported in the available literature, no shortening pin is used and this makes the fabrication of the antenna very easy. The bandwidths measured in minced pork muscles are 14% and 24% in the lower and upper ISM bands, respectively, and 12% in the midfield band. The maximum values of the realized gain of the proposed antenna obtained in the heterogeneous skin phantom at 915, 1900, and 2450 MHz are −27.2, −22.2, and −19.9 dBi, respectively. In addition, specific absorption rates (SARs) in the heterogeneous skin and muscle tissues at the three resonance frequencies are calculated and show compliance with the IEEE standards for ensuring human safety. Finally, the range of the biotelemetry link is evaluated by calculating the wireless communication link budget at data rates of 7 kb/s, 100 kb/s, and 10 Mb/s at resonance frequencies. [ABSTRACT FROM AUTHOR]

The detuning owing to the complex in-body operating scenarios, environmental factors, and circuitry of the implantable medical devices (IMDs) are the primary concerns in integrating implantable antennas with their corresponding systems. The wide bandwidth achievement for avoiding the detuning challenges is constrained by device specifications and antenna miniaturization. This study presents an ultra-miniaturized antenna of only 10.66 mm3 volume with an ultra-wide bandwidth of 3040 MHz (0.79–3.83 GHz) for a leadless pacemaker (LP). The proposed antenna encompasses the five important bands: ISM (868–868.6 MHz, 902–928 MHz, and 2.4–2.48 GHz), Wireless Medical Telemetry Service (WMTS) (1395–1400 MHz), and the midfield (1.45–1.6 GHz) bands. To consider a practical operating scenario, the antenna was integrated with a battery and controlling electronics of an LP. In a homogeneous heart phantom (HHP), the proposed antenna showed a higher gain of −28.7, −20.02, and −16.7 dBi at 915 MHz, 1.4 GHz, and 2.45 GHz, respectively. The specific absorption rate (SAR) evaluation in the heart of a realistic model guaranteed patient safety by satisfying the IEEE C95.1-2005 and C95.1-1999 guidelines. The antenna is experimentally validated through measurements in minced pork. The strength of the received signal in the measurements confirms a stable biotelemetric link of the proposed ultra-wideband (UWB) antenna with an external monitoring system. The results obtained through simulations and in vitro testing emphasized that the proposed ultra-miniaturized and UWB antenna could operate more efficiently in the heart, thus establishing itself as a suitable candidate for the LPs. [ABSTRACT FROM AUTHOR]

To maintain the compactness of future 5G smartphones, integration of sub-6 GHz and millimeter-wave (mm-wave) bands is a challenging task due to the large frequency ratio. We, therefore, propose a single-fed triple-band antenna with a large frequency ratio. The proposed antenna is composed of a microstrip patch radiator with an inverted U-shaped slot for dual-band operation in the mm-wave frequencies (28 and 38 GHz). A meandered radiating structure is linked to the microstrip patch radiator through a compact microstrip resonant cell (CMRC) low-pass filter (LPF), which is used for the integration of these structures to be operated at 3.5 GHz. A compact size of 22 mm $\times10$ mm $\times0.508$ mm for the proposed antenna was realized by incorporating the radiator slot, an LPF, the truncated ground, and a meandered line structure. Wide, decoupled −10 dB bandwidths of 12.9%, 5.8%, and 2.4% at 3.5, 28, and 38 GHz, respectively, were realized for the proposed MIMO antenna without utilizing an external decoupling structure. A detailed safety study with respect to specific absorption rates and power densities was analyzed in data, reading, and talking modes. Finally, the measurements were performed in an anechoic chamber, and the measured results were in a good correlation with the simulation results. [ABSTRACT FROM AUTHOR]

Advancement in the technology of leadless cardiac pacemakers (LCPs) has led to ultracompact designs of implantable antennas. In this study, a small-sized antenna for integration with an LCP, which can be operated in the industrial, scientific, and medical (ISM) band of 2.4 GHz, is developed. The proposed antenna was constructed in a spiral shape to provide superior miniaturization, less sensitivity to body tissue variation, and low specific absorption rate (SAR) values, and avoid fabrication complexities due to its small size. The antenna with a footprint of $3 \times 4\,\,\times0.5$ mm3 was constructed on a high dielectric material, namely, Rogers RT/duroid 6010. To the best of the authors’ knowledge, this is the smallest footprint with enhanced performance when compared to previous reports related to implantable antennas. In addition, the antenna was integrated with a 3-D 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. Due to the smooth electric field (surface currents) over the patch, the antenna system had 270.28 and 31.04 W/kg peak SAR for 1 and 10 g of tissues, respectively, 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. [ABSTRACT FROM AUTHOR]

In this article, 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 $\times 10$ mm $\times0.025$ 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 antenna’s 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 3-D-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 a minced-pork 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, −28.7, and −20.8 dBi, respectively. The measured axial-ratio bandwidths are 45.9% and 21.3% at 915 MHz and 2.4 GHz, respectively. Furthermore, 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. [ABSTRACT FROM AUTHOR]

This communication presents a compact and flexible folded dipole antenna with stable and wide-bandwidth characteristics for the application of an intraoral tongue-drive system (iTDS) designed for use by people with severe disabilities. The proposed antenna, with an exceptionally small size of 20 mm $\times \,\, 4.4$ mm $\times \,\, 0.025$ mm, was designed to overcome the challenges of space-suitability and detuning that occur due to the variable conditions of the oral environment of the mouth by providing stable and wideband antenna properties. The substantial reduction in the size of the antenna was achieved by introducing slots and meandering the arms of the radiator. Performance was analyzed in open- and closed-mouth scenarios using a realistic model of the human head. Maximum simulated impedance bandwidths of 163% and 151% were observed for the closed- and open-mouth cases, respectively. The proposed design showed lower specific absorption rate (SAR) values (addressing safety concerns) with higher realized gain values in both scenarios compared to the current state-of-the-art iTDS antennas. In order to validate the simulation results, in vivo and in vitro measurements were taken for the reflection coefficient and radiation patterns, respectively. The results prove that the proposed antenna can efficiently work in the dynamic environment of the mouth and is, therefore, a good candidate for iTDS application. [ABSTRACT FROM AUTHOR]

This communication presents a metamaterial (MTM)-loaded compact dual-band circularly polarized antenna system suitable for multiple bio-telemetric applications. The proposed antenna system operates in the industrial, scientific, and medical (ISM) bands with center frequencies: 915 MHz (902–928 MHz) and 2450 MHz (2400–2480 MHz). The integration of an MTM structure with epsilon-very-large property on the superstrate layer of the antenna produces significant gain enhancement and strong circular polarization (CP) behavior at both the operating frequencies. The key features of the proposed antenna system are its compact size (7 mm $\times 6$ mm $\times $ 0.254 mm), dual-band CP characteristics, significantly high gain values (−17.1 and −9.81 dBi in the lower and upper bands, respectively), and slot-less ground plane that reduces the complexity and backscatter radiation. The performance of the MTM-loaded antenna system is validated experimentally. The antenna is fabricated and integrated with dummy electronics and batteries and is enclosed in a 3-D printed device. The hermetically sealed device is tested in minced pork muscle to validate the simulation results. The measured impedance bandwidths of 35.8% and 17.8% are obtained in the lower and upper ISM bands, respectively. The specific absorption rate of the antenna system is evaluated at both frequencies in different tissues. Additionally, to determine the wireless communication range, the link margin is estimated at data rates of 100 kbps and 1 Mbps. [ABSTRACT FROM AUTHOR]

An intraoral tongue drive system (iTDS) is an assistive technology that enables paralyzed people to improve their lifestyle by allowing them to navigate their wheelchairs and access computers using tongue gestures. In this paper, we present two dual-band antennas: a meandered dipole antenna and a meandered planar inverted-F antenna (PIFA). We designed the proposed antennas to operate at industrial, scientific, and medical (ISM) bands 433 and 915 MHz to mitigate the external interference issue, which can severely affect frequency bands. Our proposed antenna footprints are $17.25 \times 8 \times 0.635$ mm3 and $42\times 10 \times 0.635$ mm3 for the PIFA and dipole antenna, respectively. Initially, we designed and analyzed the proposed antennas in multilayer mouth models. The performances of the antennas were validated in a realistic human head phantom. We analyzed the performances of the antennas in terms of the reflection coefficient, gain, efficiency, bandwidth, and link budget for wireless communication in four scenarios. Additionally, to address safety concerns, we calculated the specific absorption rates (SARs) for both antennas and found them to be safe according to the IEEE C95.1.2005 guideline. Finally, we measured the reflection coefficient in the more realistic environment of a 26 year-old subject’s mouth. The radiation pattern was measured in a 3-D head model and minced pork muscle, which approximated the open and closed mouth scenarios, respectively. The measurement results were in reasonable agreement with the simulation results. [ABSTRACT FROM AUTHOR]