In-body Antenna Research Articles

A Comprehensive Review of In-Body Biomedical Antennas: Design, Challenges and Applications.

In-body biomedical devices (IBBDs) are receiving significant attention in the discovery of solutions to complex medical conditions. Biomedical devices, which can be ingested, injected or implanted in the human body, have made it viable to screen the physiological signs of a patient wirelessly, without regular hospital appointments and routine check-ups, where the antenna is a mandatory element for transferring bio-data from the IBBDs to the external world. However, the design of an in-body antenna is challenging due to the dispersion of the dielectric constant of the tissues and unpredictability of the organ structures of the human body, which can absorb most of the antenna radiation. Therefore, various factors must be considered for an in-body antenna, such as miniaturization, link budget, patient safety, biocompatibility, low power consumption and the ability to work effectively within acceptable medical frequency bands. This paper presents a comprehensive overview of the major facets associated with the design and challenges of in-body antennas. The review comprises surveying the design specifications and implementation methodology, simulation software and testing of in-body biomedical antennas. This work aims to summarize the recent in-body antenna innovations for biomedical applications and indicates the key research challenges.

СТРАТЕГІЇ ТЕХНОЛОГІЧНОГО РОЗВИТКУ АПАРАТНОГО ЗАБЕЗПЕЧЕННЯ ІНФОКОМУНІКАЦІЙНИХ РАДІОМЕРЕЖ

Technologies for building telecommunication systems and networks based on 6G technology, which will be able to provide access to new functionality and information services using innovative wireless technologies and artificial intelligence methods, are considered. At the same time, information communication systems based on 6G are characterized by new functional parameters and devices, in particular, a new spectrum, new channels, new materials, new antennas, new computing technologies and new end devices, taking into account the possibility of simultaneous use of the THz range for communication and the scanning process. The operation of communication and scanning systems in new high-frequency ranges based on new materials and antennas is based on the application of silicon photonics, photonic crystals, heterogeneous, reconfigurable, photoelectric and plasmonic materials. At the same time, there is also a need to use new types of antennas for the THz frequency ranges. This is especially important, because due to significant transmission losses in the THz range, antennas are significantly different from conventional antennas that are connected to radio frequency systems via coaxial cables or microstrip lines. Given that Moore's law will soon lose its relevance, research into new computing technologies, such as computing based on artificial intelligence structures and quantum computing, has begun. The key indicators of the effectiveness of future telecommunication terminal devices as part of 6G information communication radio networks are considered and their functional capabilities are determined. The study of the architecture of terahertz communication systems was carried out using two different approaches to the construction of hardware: electronic, where radio frequencies are multiplied up to THz; and photonic, where optical frequencies are divided up to THz. It has been determined that most of such systems and networks are used for communication over short distances inside premises due to high atmospheric attenuation in the THz range. The prerequisites for achieving higher characteristics due to the addition of new materials to the silicon chip, such as photonic crystals, photovoltaic elements and plasma surfaces, are considered. As a result, new on-chip and in-body antenna designs, along with compact lens technology such as RIS, can provide more accurate implementation of the desired antenna characteristics, as well as reduce system size. Opportunities to use new communication and visualization methods have been identified, but implementation of terahertz systems based on electronics, optoelectronics, and photonics will depend on the usage scenario and operating frequencies.

Reconfigurable Dual-Band Capsule-Conformal Antenna Array for In-Body Bioelectronics

Wireless in-body bioelectronics offer powerful biosensing and therapeutic capabilities. Efficient and robust in-body antenna designs are required to ensure a reliable through-body link, increase data rates, and reduce power budgets. This study proposes and demonstrates a pattern- and frequency-reconfigurable capsule-conformal antenna array that responds to the challenges of next-generation in-body bioelectronics. The array comprises two mirrored dual-band elements operating at 434 MHz and 2.45 GHz ISM bands. Tissue-matched dielectric loading of the array improves the radiation efficiency and ensures quasi tissue-independent operation for both bands. Due to the full ground plane, the antenna is shielded from the capsule payload. The achieved efficiencies are compared to the fundamental limitations and closely approach them. The realized gains are −28.9 and −18.6 dBi at 434 MHz and 2.45 GHz, respectively, when the array is placed in the center of a ø100-mm diameter spherical phantom with muscle-equivalent properties. Using a single switch, the array can be reconfigured to adjust the angular position of the nulls in the radiation pattern in both bands thereby enabling synthesis of an effectively null-free omnidirectional pattern. The array prototypes are fabricated, and the impedance and far-field radiation patterns are characterized to validate the design in tissue-equivalent liquid phantoms.

A Wideband Bear-Shaped Compact Size Implantable Antenna for In-Body Communications

Biomedical implantable antennas play a vital role in medical telemetry applications. These types of biomedical implantable devices are very helpful in improving and monitoring patients’ living situations on a daily basis. In the present paper, a miniaturized footprint, thin-profile bear-shaped in-body antenna operational at 915 MHz in the industrial, scientific, and medical (ISM) band is proposed. The design is a straightforward bear-shaped truncated patch excited by a 50-Ω coaxial probe. The radiator is made up of two circular slots and one rectangular slot at the feet of the patch, and the ground plane is sotted to achieve a broadsided directional radiation pattern, imprinted on a Duroid RT5880 roger substrate with a typical 0.254-mm thickness ( ϵr = 2.2, tan δ = 0.0009). The stated antenna has a complete size of 7 mm × 7 mm × 0.254 mm and, in terms of guided wavelength, of 0.027λg × 0.027λg × 0.0011λg. When operating inside skin tissues, the antenna covers a measured bandwidth from 0.86 GHz to 1.08 GHz (220 MHz). The simulations and experimental outcomes of the stated design are in proper contract. The obtained results show that the calculated specific absorption rate (SAR) values inside skin of over 1 g of mass tissue is 8.22 W/kg. The stated SAR values are lower than the limitations of the federal communications commission (FCC). Thus, the proposed miniaturized antenna is an ultimate applicant for in-body communications.

A Compact Flexible Circularly Polarized Implantable Antenna for燘iotelemetry Applications

With the help of in-body antennas, the wireless communication among the implantable medical devices (IMDs) and exterior monitoring equipment, the telemetry system has brought us many benefits. Thus, a very thin-profile circularly polarized (CP) in-body antenna, functioning in ISM band at 2.45 GHz, is proposed. A tapered coplanar waveguide (CPW) method is used to excite the antenna. The radiator contains a pentagonal shape with five horizontal slits inside to obtain a circular polarization behavior. A bendable Roger Duroid RT5880 material (εr = 2.2, tanδ = 0.0009) with a typical 0.25 mm-thickness is used as a substrate. The proposed antenna has a total volume of 21 × 13 × 0.25 mm3. The antenna covers up a bandwidth of 2.38 to 2.53 GHz (150 MHz) in vacuum, while in skin tissue it covers 1.56 to 2.72 GHz (1.16 GHz) and in the muscle tissue covers 2.16 to 3.17 GHz (1.01 GHz). GHz). The flexion analysis in the x and y axes was also performed in simulation as the proposed antenna works with a wider bandwidth in the skin and muscle tissue. The simulation and the curved antenna measurements turned out to be in good agreement. The impedance bandwidth of −10 dB and the axis ratio bandwidth of 3 dB (AR) are measured on the skin and imitative gel of the pig at 27.78% and 35.5%, 13.5% and 4.9%, respectively, at a frequency of 2.45 GHz. The simulations revealed that the specific absorption rate (SAR) in the skin is 0.634 and 0.914 W/kg in muscle on 1g-tissue. The recommended SAR values are below the limits set by the federal communications commission (FCC). Finally, the proposed low-profile implantable antenna has achieved very compact size, flexibility, lower SAR values, high gain, higher impedance and axis ratio bandwidths in the skin and muscle tissues of the human body. This antenna is smaller in size and a good applicant for application in medical implants.

Propagation-Loss Characterization for Livestock Implantables at (433, 868, 1400) MHz

Automated systems based on wearable sensors for livestock monitoring are becoming increasingly popular. Specifically, wireless in-body sensors could yield relevant data, such as ruminal temperature. The collection of such data requires an accurate characterization of the in-to-out body wireless channel between the in-body sensor and the gateway. The aim of this study is to experimentally characterize the in-to-out-body propagation loss for cows and horses at 433, 868, and 1400 MHz. Measurements were conducted in vivo on five different fistulated cows and five horse cadavers using specialized robust in-body capsule antennas inside the animals' abdomen. Next, the in-body antenna gain was deembedded from the wireless channel, and the in-to-out body propagation loss was obtained as the difference between measured unobstructed line-of-sight path losses and in-to-out-body path losses. The measurements showed a body propagation loss of (mean ± standard deviation) 30.8 ± 4.1 dB, 44.5 ± 4.8 dB, and 54.2 ± 4.7 dB for cows at 433, 868, and 1400 MHz, respectively. For horses, the body propagation losses were 23.2 ± 3.8 dB, 31.0 ± 4.7 dB, and 44.4 ± 3.2 dB at 433, 868, and 1400 MHz, respectively. These results are important to determine the wireless range of WBANs to optimize the network topology and estimate the associated network cost for large-scale monitoring systems.

Simulation and Measurement Data-Based Study on Fat as Propagation Medium in WBAN Abdominal Implant Communication Systems

This paper presents comprehensive study on fat as propagation medium in abdominal implant communication system at low ultrawideband (UWB) frequency range 3.75-4.25 GHz. The main aim is to investigate how signal propagates through visceral and subcutaneous fat layers and how that information can be exploited in implant communication systems. The study is conducted using different methods: electromagnetic simulations, power flow analysis, propagation path calculations and radio channel measurements with animal meat pieces. Simulations are conducted using layer models and anatomical voxel models having different sizes. Results of channel simulations are verified with propagation path calculations. Power flow analysis on cross-cuts of the voxel models is conducted to investigate how the signal propagates inside the tissues. Furthermore, measurements using different animal meat pieces are performed to evaluate the impact of fat constitution on channel characteristics. It is found that similar tendency on fat propagation is seen in the evaluations with different methods. It is also observed that channel attenuation depends not only on the types and thicknesses of the tissues between transmitter and receiver antennas, but also how the tissues, especially fat, is located between the antennas. Channel attenuation difference between different voxels is maximum 14 dB in the studied antenna locations. Furthermore, propagation channel is evaluated with measurements using pork meat having different fat and muscle constitutions. It is found that antenna location respect to fat layers has clear impact on the channel strength although the fat tissue is not directly above the in-body antenna. The difference is noted to be 3-15 dB especially on the side peaks of channel impulse response. The knowledge on fat as a propagation medium is crucial when designing medical monitoring or implant communication systems. Location of antennas/sensor nodes for the monitoring devices can be established so that propagation through fat layer can be exploited.

Miniaturized Dual-Resonant Helix/Spiral Antenna System at MHz-Band for FSK Impulse Radio Intrabody Communications

In this article, a miniaturized dual-resonant antenna system at MHz-band operating at around 20 and 50 MHz is proposed for frequency-shift keying impulse radio (FSK-IR) intrabody communications. This antenna system comprises a swallowable helix-coil in-body antenna with a hollow cylindrical shape of 10 mm diameter and 30 mm length, and two single band on-body matched planar spiral-coil antennas with a compact size of 79 mm $\times\,\,72$ mm $\times\,\,2.8$ mm. For in-body antenna design, a nonuniform helical pitch structure is utilized to produce dual-resonant frequencies. The soft ferrite magnetic sheet with high relative permeability and low dissipation factor is used as a flexible conformal substrate to realize antenna miniaturization without lumped element loading. Simulation results for antenna performance, electromagnetic field distribution, and specific absorption rate are presented with different tissue-type phantoms, as well as an anatomical numerical human model. In addition, experimental verification of antenna performance and implant transmission characteristics is also conducted in a liquid phantom. At an implant depth of 50 mm, the measured maximum transmission coefficients are −33 and −45 dB at the dual-resonant frequency bands, respectively. Simulation and measurement results demonstrate that the proposed dual-resonant antenna is suitable for the FSK-IR system and can be expected to realize a data rate as high as 10 Mb/s for biomedical implant applications at MHz-band.

A Review of Wireless Body Area Networks for Medical Applications

Recent advances in Micro-Electro-Mechanical Systems (MEMS) technology, integrated circuits, and wireless communication have allowed the realization of Wireless Body Area Networks (WBANs). WBANs promise unobtrusive ambulatory health monitoring for a long period of time, and provide real-time updates of the patient’s status to the physician. They are widely used for ubiquitous healthcare, entertainment, and military applications. This paper reviews the key aspects of WBANs for numerous applications. We present a WBAN infrastructure that provides solutions to on-demand, emergency, and normal traffic. We further discuss in-body antenna design and low-power MAC protocol for a WBAN. In addition, we briefly outline some of the WBAN applications with examples. Our discussion realizes a need for new power-efficient solu-tions towards in-body and on-body sensor networks.

Body Implanted Medical Device Communications

The medical care day by day and more and more is associated with and reliant upon concepts and advances of electronics and electromagnetics. Numerous medical devices are implanted in the body for medical use. Tissue implanted devices are of great interest for wireless medical applications due to the promising of different clinical usage to promote a patient independence. It can be used in hospitals, health care facilities and home to transmit patient measurement data, such as pulse and respiration rates to a nearby receiver, permitting greater patient mobility and increased comfort. As this service permits remote monitoring of several patients simultaneously it could also potentially decrease health care costs. Advancement in radio frequency communications and miniaturization of bioelectronics are supporting medical implant applications. A central component of wireless implanted device is an antenna and there are several issues to consider when designing an in-body antenna, including power consumption, size, frequency, biocompatibility and the unique RF transmission challenges posed by the human body. The radiation characteristics of such devices are important in terms of both safety and performance. The implanted antenna and human body as a medium for wireless communication are discussed over Medical Implant Communications Service (MICS) band in the frequency range of 402-405MHz.