Industrial Scientific Medical Research Articles

Multi-switch-controlled multi-mode TRFE with a high-linearity ATRSW for 2.4-GHz ISM applications

This paper presents a multi-switch-controlled multi-mode transceiver front end (TRFE) designed for the 2.4-GHz industrial–scientific–medical (ISM) band, with a particular focus on enhancing the linearity of the transmit/receive switch (TRSW) on the antenna side. Considering the distinct power levels in the RX/TX paths, the TRSW is designed to be asymmetric. This design not only elevates IP-0.1dB by over 50 % compared to the conventional symmetric topology, but also absorbing its function into the input matching network (IMN) of the low noise amplifier (LNA), thereby minimally impacting the noise figure (NF) of the RX chain. For the TX path, the high-pass component of the power amplifier (PA) output matching network (OMN) is repurposed, with a singular inductor being redeployed to serve as an inductive ESD safeguard. Moreover, the driving stage employs a passive gain-boosting technique, which elevates the gain by 3 dB compared to the traditional cascode structure. For verification, this TRFE is fabricated in 0.18-μm CMOS with a die size of 1.53 mm2. It achieves a NF of 2.4 dB and a RX gain of 16.7 dB under a 3.3-V supply. A TX gain of 26.2 dB and a saturation output power of 23.3 dBm with a peak power-added efficiency (PAE) of 38.8 % are also demonstrated.

A unified approach for breast cancer discrimination using metasurface-based microwave technology

Multifocal (MF) and multicentric (MC) breast cancers are more likely to be aggressive than unifocal (UF) breast tumors, and they are linked to high recurrence probability, lymph node metastases, and low survival rates. Metastasis is the process through which cancer cells spread to different body areas. Although the longevity of patients with metastatic breast cancer is high, it is restricted by the growth of brain metastases. Medical imaging techniques have inherent limits. Hence, a precise and sensitive substitution is required. Because microwave imaging is portable, non-ionizing, and affordable, it has become a viable method for the detection of breast cancer. As far as we know, this is the first research aiming at discriminating MF and MC breast cancers from UF ones. This proposal presents a 2×2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2\ imes 2$$\\end{document} planar metasurface-based array antenna in the Industrial Scientific Medical frequency band at 2.4 GHz. The proposed array configuration significantly enhanced the gain to 4 dBi rather than a single element at 50 Ω. The geometric arrangement of the four antenna elements is optimized to discriminate the critical stage of breast cancers (UF, MF, or MC). As the proposed structure does not surround the breast, it contributes to a higher degree of comfort than the conventional antenna configurations. The magnitude and phase of S-parameters of the backscattered signals are analyzed in this research.

Design of new tuning circuit based reconfigurable microstrip antenna for S, C, X, and Ku bands applications

ABSTRACT A new reconfigurable microstrip has been designed, and manufactured via tuning and switching components. The antenna can swipe among various frequencies. Several operational modes have been tested, and measured via Vector Network Analyzer (VNA). A circular patch is considered complicated in design calculations. Therefore, the proposed antenna intended a reduction in scheming via an uncomplex structure. Tow-tuning capacitors have been added to function in multi-bands. Also, hybrid connections between capacitors and switching diodes have been used for the reconfiguration technique. A compressed size of 31 × 27 (mm), low-priced, straightforward structured antenna operates in various modes at the following frequency bands: S-band at 2, 2.09, 2.18, 2.27, and 2.4 GHz, C band at 4.9, 7.7, and 7.9 GHz, X band at 10.5, and 10.7 GHz, and Ku band at 13.3, 13.4, 14.9, 15.2, 15.5,15.6, 17.4, 17.5, and 17.6 GHz. The reconfigurable antenna offered a peak radiation efficiency of 79% and peak gain of 7.3 dB under all tested scenarios. The proposed reconfigurable microstrip antenna is appropriate to function in recent wireless communication technologies such as industrial scientific medical (ISM) bands (Wi-Fi, Bluetooth, ZigBee, WiMAX, IoT, etc.), 5G applications, fixed wireless systems (FWS), 4G (LTE), and satellite communications.

A review on miniature bio-implant antenna performance enhancement and impact analysis on body fluids in medical application

Nowadays, the attention is on building an efficient and constantly evolving healthcare system for the human body is keep on increasing. Implantable devices introduced with pacemakers have become more phenomenal in the health care system nowadays. This paper discusses the recent advancements in bio-implanted antennas and various antenna structures proposed by investigators for biomedical applications. It also summarises the design need, antenna structures, dimensions, and features in the Medical Implanted Communication System band and Industrial Scientific Medical band. The antenna is implanted into the human body and embedded with a bio-medical sensor. The signal from the sensor is radiated by the antenna outside of the body to be analyzed by the receiver. Bio-implanted antennas based on microstrip structure have a negative gain (low radiation) due to body fluids. The motto of the review paper is to deliver attention for production with subjects related to Biocompatibility, Miniaturization, Biomedical sensors with implanted antenna, and increased quality of communication with an external receiver. It also highlights and focuses on the gain improvement of the microstrip antenna within the human body to get effective radiation. Moreover, the several experimental setups of the bio-implanted antenna with biomedical sensors are summarised in many biomedical applications such as glucose, deep brain stimulation, endoscopy, laparoscopy, pacemaker, temperature and blood pressure monitor.

An Ultra-Low-Voltage 2.4-GHz Flicker-Noise-Free RF Receiver Front End Based on Switched-Capacitor Hybrid TIA With 4.5-dB NF and 11.5-dBm OIP3

In this article, an ultra-low-voltage 2.4-GHz radio frequency (RF) receiver front-end architecture targeting the removal of output flicker noise is presented, making it possible to use zero-IF topology for narrow-band communication standards. The trans-impedance amplifier (TIA) is built on the proposed hybrid operational trans-conductance amplifier (OTA) with a switched-capacitor (SC) amplifier as the first gain stage and an active primary–secondary amplifier as the second gain stage, achieving an imperceptible flicker-noise corner frequency. With the SC gain stage, the interstage common-mode voltage can be set to 0 V, which reduces the minimum supply voltage to 0.5 V. As another benefit, dc offset compensation (DCOC) is performed inherently in the interstage sampling and coupling process. Fabricated in 28-nm RF CMOS process, the front-end prototype, including an on-chip matching inductor, occupies a die area of 0.8 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> . Operating in the Industrial Scientific Medical (ISM) frequency band of 2.4 GHz with 1-MHz IF bandwidth, the front end provides a 36–40-dB conversion gain, an 11.5-dBm OIP3, and a flicker-noise corner frequency less than 10 kHz with the supply voltage ranging from 0.5 to 0.6 V. The RF impedance matching network provides passive voltage gain before the low-noise trans-conductance amplifier (LNTA), achieving a 4.5-dB noise figure (NF) with 0.8-mA biasing current in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_m$</tex-math> </inline-formula> stage. With the ultra-low supply voltage and the passive IF gain stage, the power consumption of the proposed front end is only 610 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula> W under a 0.53-V supply voltage.

Deep reinforcement learning based spectrum prediction for bursty bands

Spectrum prediction plays an important role for the secondary user (SU) to utilize the shared spectrum resources. However, currently utilized prediction methods are not well applied to spectrum with high burstiness, as parameters of prediction models cannot be adjusted properly. This paper studies the prediction problem of bursty bands. Specifically, we first collect real WiFi transmission data in 2.4GHz Industrial, Scientific, Medical (ISM) band which is considered to have bursty characteristics. Feature analysis of the data indicates that the spectrum occupancy law of the data is time-variant, which suggests that the performance of commonly used single prediction model could be restricted. Considering that the match between diverse spectrum states and multiple prediction models may essentially improve the prediction performance, we then propose a deep-reinforcement learning based multilayer perceptron (DRL-MLP) method to address this matching problem. The state space of the method is composed of feature vectors, and each of the vectors contains multi-dimensional feature values. Meanwhile, the action space consists of several multilayer perceptrons (MLPs) that are trained on the basis of multiple classified data sets. We finally conduct experiments with the collected real data and simulations with generated data to verify the performance of the proposed method. The results demonstrate that the proposed method significantly outperforms the state-of-the-art methods in terms of the prediction accuracy.

Notch-band eliminator wideband CSRR loaded monopole fractal antenna for ISM and PCS communications

PurposeThis paper aims to present a low-cost, edge-fed, windmill-shaped, notch-band eliminator, circular monopole antenna which is practically loaded with a complementary split ring resonator (CSRR) in the middle of the radiating conductor and also uses a partial ground to obtain wide-band performance.Design/methodology/approachTo compensate for the reduced value of gain and reflection coefficient because of the full (complete) ground plane at the bottom of the substrate, the antenna is further loaded with a partial ground and a CSRR. The reduction in the length of ground near the feed line improves the impedance bandwidth, and introduced CSRR results in improved gain with an additional resonance spike. This results in a peak gain 3.895dBi at the designed frequency 2.45 GHz. The extending of three arms in the circular patch not only led to an increase of peak gain by 4.044dBi but also eliminated the notch band and improved the fractional bandwidth 1.65–2.92 GHz.FindingsThe work reports a –10dB bandwidth from 1.63 GHz to 2.91 GHz, which covers traditional coverage applications and new specific uses applications such as narrow LTE bands for future internet of things (NB-IoT) machine-to-machine communications 1.8/1.9/2.1/2.3/2.5/2.6 GHz, industry, automation and business-critical cases (2.1/2.3/2.6 GHz), industrial, society and medical applications such as Wi-MAX (3.5 GHz), Wi-Fi3 (2.45 GHz), GSM (1.9 GHz), public safety band, Bluetooth (2.40–2.485 GHz), Zigbee (2.40–2.48Ghz), industrial scientific medical (ISM) band (2.4–2.5 GHz), WCDMA (1.9, 2.1 GHz), 3 G (2.1 GHz), 4 G LTE (2.1–2.5 GHz) and other personal communication services applications. The estimated RLC electrical equivalent circuit is also presented at the end.Practical implicationsBecause of full coverage of Bluetooth, Zigbee, WiFi3 and ISM band, the proposed fabricated antenna is suitable for low power, low data rate and wireless/wired short-range IoT-enabled medical applications.Originality/valueThe antenna is fabricated on a piece (66.4 mm × 66.4 mm × 1.6 mm) of low-cost low profile FR-4 epoxy substrate (0.54 λg × 0.54 λg) with a dielectric constant of 4.4, a loss tangent of 0.02 and a thickness of 1.6 mm. The antenna reflection coefficient, impedance and VSWR are tested on the Keysight technology (N9917A) vector network analyzer, and the radiation pattern is measured in an anechoic chamber.

Circular Shape Microstrip Patch Antenna for Body Area Network Application

In wireless communication system antenna plays crucial role. Thus, antenna used every wireless communication system should be low weight, low profile, low cost, smaller in dimension and conformity. A microstrip patch antenna fulfils all these requirements. In this paper a circular shaped microstrip patch antenna for Body Area Network (BAN) application in the 2.45 GHz ISM (Industrial Scientific Medical) band is suggested. To enhance Specific Absorption Rate (SAR). The suggested antenna offers a gain of over 1 dB for the whole 2.45 GHz ISM band application of proposed antenna is in fields of Medical, Military, Sports, Defence etc. Various antenna parameters like return loss, VSWR, directivity, gain etc has been computed and analyzed using HFSS software.

Design of a Flexible Cylindrical Antenna with Rotatable Curved Frequency Selective Surface for Omnidirectional High-Gain Applications

In this paper, a high-gain flexible cylindrical antenna with rotatable curved frequency selective surface (FSS) is presented, which is designed for the 2.4 GHz industrial scientific medical (ISM) band. The array of 3 × 3 optimized FSS unit cells (102 × 102 mm2) is applied to improve the gain of the antenna (50.4 × 28 × 0.1 mm3). Through the rotation of the FSS, omnidirectional gain enhancement is realized. The simulation and measurement results demonstrate the feasibility of this work. The measured antenna with the FSS has omnidirectional high-gain in the operational band of 2.18–2.90 GHz, and the gain can be increased by 5.31 dBi at most. The antenna can be used in cylindrical conformal devices, and the proposed design method provides a new solution for gain enhancement of cylindrical omnidirectional antennas.

A Body-Wide RF Energy Harvester Based on Textile Surface Plasmonic Antenna Array for Wearable Wireless Power Transmission

This brief demonstrated a body-wide RF energy harvester based on textile spoof surface plasmon (SSP) antenna array for wearable wireless power transmission. This harvester includes four patch antennas and SSP waveguides to form an SSP antenna array integrated with clothing to harvest the incident RF energy. Then, a loop and rectifier are integrated and fabricated in the same plane to extract, combine, rectify and output DC power from the multi-path harvested energy in a contactless way and without a complex matching network. They are fabricated with a simple structure, entirely off-the-shelf flexible and textile materials, and a proven fabrication technique. Finally, it is worn on the body to output DC power of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$108.89~\mu \text{W}$ </tex-math></inline-formula> when illuminated with a power density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.96~\mu \text{W}$ </tex-math></inline-formula> /cm2 at 2.4-2.45 GHz Industrial Scientific Medical (ISM) band. This design could be applied to power the potential wearable sensors wirelessly.

Modeling of a Compact, Implantable, Dual-Band Antenna for Biomedical Applications

Different implantable antenna designs exist to establish communication with implantable devices depending on the domain of use and the implantation space. Owing to their nature and purposes, these antennas have many imposed criteria on various characteristics, such as bandwidth, multiband behavior, radiation pattern, gain, and specific absorption rate (SAR). This presents a challenge when it comes to achieving satisfying results without a major compromise in any of these crucial parameters. Additionally, many of the existing designs do not follow a specific approach to obtain results. Measuring different parameters of such fabricated structures requires special conditions and special environments mimicking the tissues where they are supposed to be placed. For such issues, the use of biological or synthetic phantoms is widely employed to validate what is obtained in simulation, and a multitude of formulas exist for the creation of such phantoms, each with its advantages and drawbacks. In this paper, a miniature dual-band structure derived from the first iteration of the Koch fractal structure is designed to operate 2 mm below the skin in the arm of the human body, with the MICS (Medical Implant Communication System) and ISM (Industrial, Scientific, Medical) 2.4 GHz bands. The purposes of the design are to derive structures from commonly used shapes with certain behavior while maintaining miniaturization, and to easily design dual-band implantable antennas. More than one band is used to diversify uses, since bands such as the MICS band are mainly dedicated to telemetry. The structure is characterized not only by its low profile compared to various structures found in the literature with dimensions of 17.2 × 14.8 × 0.254 mm3, but also its ease of design, independent shifting of resonant frequencies, and the absence of the need for a matching circuit and a shorting pin (via) for miniaturization. It exhibits satisfying performance: bandwidths of 23 MHz in the MICS band and 190 and 70 MHz in the vicinity of the ISM 2.4 GHz band, and measured gain in the latter band of −18.66 and −17 dBi in the azimuth and elevation radiation patterns, respectively. To validate the antenna’s properties in a skin-mimicking environment, two simple phantom formulas found in the literature were explored and compared in order to identify the best option in terms of accuracy and ease of fabrication.

Elastomeric Textile Substrates to Design a Compact, Low-Profile AMC-Based Antenna for Medical and IoT Applications

A neoteric, compact, low-profile, wide-band elastomeric textile antenna for medical and IoT applications is presented. The design synthesis of flexible artificial magnetic conductor (AMC)-integrated antenna is done using stratum of textile and operates within 4.76–6.08 GHz covering the 5.8-GHz industrial, scientific, medical (ISM) and 5-GHz Wi-Fi band for IoT applications. The rectangular fed design operates in the high frequency band which is widened and optimized to operate in the lower 5-GHz band and the notch etched with the monopole’s edges, suppress the cross-polarization component. The suggested design features an impedance bandwidth of 24.4% with a high gain of 10.59 dBi and has a compact footprint of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.44\lambda _{0}\times $ </tex-math></inline-formula> 0.46 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}\times $ </tex-math></inline-formula> 0.0512 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> . Simulation and experimental studies provide evidence that in the case of structural deformities, such as bending and crumpling and also for human body loading, the suggested AMC-integrated antenna is stable and shows superior efficiency relative to the traditional monopole antenna. Thus, to a large extent, the antenna is stable to maintain its radiation properties. Furthermore, numerical analysis demonstrates maximum amount of the specific absorption rate (SAR) is 0.0832 W/Kg according to IEEE standard safety guidelines. The advantage of the suggested AMC-integrated antenna design is that it is resilient to moisture conditions and the enhancement in impedance bandwidth is achieved by simple cut edges in the radiator and the ground plane leading to a simple staircase design. In addition, the simulation and measurement results are consistent, thus confirming it to be a promising contender for sensing and applications in body-centric wireless communications and Internet of Things.

A Novel Patterned Ground Structure With Shunt and Series Lumped Elements for Synthesizing Absorption Common-Mode Filters

To synthesize an absorption common-mode filter (A-CMF) in a two-layer printed circuit board, patterned ground structures (PGSs) have been studied in the past few years. A conventional PGS consists of slotlines and shunt lumped elements across slots. On the contrary, the proposed new PGS uses both shunt and series lumped elements (SSLEs) in a ground plane with a closed-loop asymmetrical coplanar strip. To validate the proposed SSLE PGS, two circuits of bidirectional A-CMFs are developed to absorb common-mode (CM) noise in the 2.4 GHz industrial scientific medical (ISM) band. The one with higher CM noise absorption bandwidth is finally implemented and demonstrated in this article. Besides, nonideal CM return current paths are considered to modify the ideal circuit and reduce the discrepancies between the full-wave and circuit simulations. The measurement results show that the proposed bidirectional A-CMF attains CM noise absorption from 2.29–2.57 GHz for electromagnetic interference suppression in the 2.4 GHz ISM band. Most of all, the proposed work reveals a notable differential-mode −3 dB bandwidth up to 16.3 GHz with an ultracompact size of 0.0143 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _g^2$</tex-math></inline-formula> .

Energy-Efficient UAV-Based IoT Communications With WiFi Suppression in 5 GHz ISM Bands

Unmanned Aerial Vehicle (UAV) based communication is a promising technology for offering wireless communication services. UAVs can typically be adopted as aerial base stations to collect data from ground Internet of Things (IoT) devices. However, the Ground-to-Air link of UAV-based IoT communications is prone to be interfered by surrounding WiFi devices in the Industrial, Scientific, Medical (ISM) band. This paper aims to enable reliable uplink communications for IoT devices in 5 GHz ISM bands, thereby reducing the hover time and energy consumption of the UAV. To this end, we first study and design suppression frames suitable for WiFi devices. Then a suppression method is proposed, which is shown to be effective for all the tested devices, based on emulation performance verification of the frames for multiple commercial off-the-shelf (COTS) WiFi devices. Moreover, by taking the energy consumption of the UAV and multiple transmission parameters of the suppression method into account, we formulate an optimization problem for the desired uplink, which is designed to minimize the energy consumption of the UAV, under the constraints of satisfying the link channel capacity. Given that the optimization problem is non-convex mixed-integer nonlinear programming, this paper proposes an efficient algorithm that takes advantage of the suppression performance of the utilized frames. Numerical simulations demonstrate the performance of the proposed algorithm in terms of the WiFi device density, UAV weight, channel capacity requirement and parameters of the suppression method. The communication quality of the desired Ground-to-Air link is shown to be significantly improved, while the consumed energy is demonstrated to be obviously reduced.

A Low-Profile Antenna for On-Body and Off-Body Applications in the Lower and Upper ISM and WLAN Bands.

The article presents a Co-planar Waveguide (CPW) fed antenna of a low-profile, simple geometry, and compact size operating at the dual band for ISM and WLAN applications for 5G communication devices. The antenna has a small size of 30 mm × 18 mm × 0.79 mm and is realized using Rogers RT/Duroid 5880 substrate. The proposed dual-band antenna contains a CPW feedline along with the triangular patch. Later on, various stubs are loaded to obtain optimal results. The proposed antenna offers a dual band at 2.4 and 5.4 GHz while covering the impedance bandwidths of 2.25-2.8 GHz for ISM and 5.45-5.65 GHz for WLAN applications, respectively. The proposed antenna design is studied and analyzed using the Electromagnetic (EM) High-Frequency Structure Simulator (HFSSv9) tool, and a hardware prototype is fabricated to verify the simulated results. As the antenna is intended for on-body applications, therefore, Specific Absorption Rate (SAR) analysis is carried out to investigate the Electromagnetic effects of the antenna on the human body. Moreover, a comparison between the proposed dual-band antenna and other relevant works in the literature is presented. The results and comparison of the proposed work with other literary works validate that the proposed dual-band antenna is suitable for future 5G devices working in Industrial, Scientific, Medical (ISM), and Wireless Local Area Network (WLAN) bands.

Reduced-size Biocompatible Implantable Planar Inverted F- Antenna

The existence of implantable antennas presents intrinsic challenges as the performance of the antenna degrades due to the high losses of body tissues. In this study, a reduced-size Planar Inverted F- Antenna (PIFA) operating at Industrial, Scientific Medical (ISM) band (2.4 GHz) is designed and optimized. The design of PIFA is modeled to study and analyze the effect on the implantable antenna by placing it within the human body model, particularly in the arm. Copper is used as the patch material and the ground layer of the proposed antenna with Rogers RO3210 as its substrates. The simulation was carried within the human fat layer which is sandwich between the skin dan muscle layer. The design optimization of the antenna for operation in a human fat layer with optimal performance was achieved by reducing the size of the antenna. The antenna exhibits good stability with the reflection coefficient, S11 ≤ -10 dB at 2.4 GHz suitable for WBAN application in the environment of the human fat layer for near field communication. Analysis performance of the antenna was conducted by the transient movement of the antenna position due to the antenna being prone to movement when it is implanted within the body. The transient movement analysis is done when the implantable antenna is moving toward the skin layer and toward the muscle layer from the initial position within the fat layer. Additionally, 1 mm, 2 mm, interface of the layer and when the antenna within another tissue layer has been set to examine the performance of the implantable antenna. Correspondingly, simulation results indicate the impact of the human body layer due to the electrical properties of the human body in terms of conductivities, permittivity, and thicknesses of the layers. This has shown the design optimization of the antenna satisfies all requirements for an implantable antenna, such as small size of 5.08 × 4.00 × 0.66 (), biocompatible, low reflection coefficient of -42 dB at 2.4 GHz, realized gain of -18 dBi suitable for near field communication, and acceptable performance in fat layer. Future work will expand on conducting Specific Absorption Rate (SAR) to study the high attenuation of the radiated power of the human body on implanted antennas for the safety reason to bring in real life where it is being performed and examined.

Designing and analyzing multi-coil multi-layers for wireless power transmission in stent restenosis coronary artery

Wireless power transfer technology features shorter power transmission distances in biomedical applications. This is a result of the small size of the implanted coils, biocompatible material conductivity, and the large distances between the receiving and transmitting coils. There have been numerous attempts to improve the power transfer efficiency across longer distances. Multiple coils, including 2-, 3-, 4-, and multi-layered coils, were previously considered. This study proposes a novel approach to achieve higher power transmission efficiency by integrating a single coil on the receiving side and three asymmetric coils on the transmitter side. As such, it delivers power to the sensor implanted within the coronary artery that monitors the blood pressure while introducing a uniquely shaped stent. The efficiency of power transmitted to the stent in its dual implanted forms, helical and zigzag helical, was examined as well, with the wireless power transmission system thereby analyzed at the 27 MHz Industrial Scientific Medical band operating frequency. For the four-coil technique, the power transmission efficiency at a distance of 25 mm between the receiver and transmitter sides by using biological human tissue as a medium between the transmission coils and the receiver stent can reach 56.42%, whereas other approaches show lower efficiencies: the three-coil method’s efficiency is 32.88%, the double-layer parallel method’s efficiency is 27.75%, the two-coil method’s efficiency is 24.76%, the triple-layer parallel method’s efficiency is 17.31%, the double-layer series method’s efficiency is 0.501%, and the triple-layer series method’s transmission efficiency is 0.092%. In addition, the suggested approach is demonstrated to be more efficient than prior designs with regard to the size of the implanted coils, which represent stents.

A triple-band spiral-shaped antenna for high data rate fully passive implantable devices

A spiral-shape, multi-band and compact antenna for healthcare and high-speed biomedical devices is presented. It operates simultaneously at 2.4/5.8 GHz of the industrial scientific medical (ISM) band and 4.8 GHz as the first-band harmonic. Therefore, it is suitable for fully-passive in-body systems. The compact size of the designed antenna is 9.2 × 9.2 × 0.5 mm3 and shorting pins are not used to reduce the dimensions. The results have been checked by full wave software in both three-layer and one-layer phantoms with different body tissues. The presented antenna has been embedded in two implantable systems and integrated with other components to evaluate real working scenarios. In addition, for safety study and numerical analysis of radiation absorption per unit mass of human tissue, the antenna specific absorption rate (SAR) has been analyzed. The designed antenna has been implanted in a muscle liquid phantom and parameters were evaluated experimentally. The proposed antenna exhibits multi-band characteristics, has a via-less and simple configuration, a compact size, low SAR, and suitable gain value making it a proper and applicable choice for implantable passive devices.

Wearable Panda-Shaped Textile Antenna with Annular Ring-Defected Ground Structure for Wireless Body Area Networks

This research presents a compact panda-shaped wearable antenna with a defected ground structure (DGS). It is fabricated using a flexible material to work at 2.4-GHz industrial scientific medical (ISM) band, confirming the wireless body area network (WBAN) application requirements. The annular ring DGS and circular and elliptical slots in the patch aid in achieving the operating frequency. Good impedance bandwidth is maintained during on-body and bending analysis. Furthermore, this antenna exhibits a peak gain of 7.3 dB and a minimum specific absorption rate (SAR) of 0.0233 W/kg for 1 g tissue and 1.02 W/kg for 10 g tissue. The investigation shows that an antenna with good robustness, compact, high flexibility, and very low SAR makes it a strong candidate for WBAN applications.

A Conformal Four-Antenna Module for Capsule Endoscope MIMO Operation

In this article, a four-antenna module in a capsule endoscopy is proposed for multiple-input multiple-output (MIMO) operation to achieve the purpose of real-time transmission of high-resolution images with high data rates. For compactness, the proposed design adopts conformal architecture and fully utilizes the inner wall space of the capsule body to accommodate four antennas in the very limited space of the capsule endoscope. For the availability of MIMO operation, three different technical approaches are used to decouple or improve the isolation between neighboring antenna elements and between diagonal antenna elements. System considerations (interaction between the electronic components and the antenna in the endoscope) and specific absorption ratio (SAR) evaluation are performed to verify the robustness and human safety of the proposed design, respectively. In addition, link margin analysis and MIMO channel parameter studies are carried out to verify the wireless telemetry performance and MIMO operation performance, respectively. Antenna prototypes were fabricated and implanted in minced pork for ex-vivo measurements (S-parameters, gain, and radiation patterns). The measured overlapping impedance bandwidth of the four antenna elements is 120 MHz, which can fully cover the 915 MHz industrial scientific medical (ISM) band. The measured isolation between the neighboring antenna elements and the diagonal antenna elements is better than 20 and 10 dB, respectively. The measured maximum peak realized gain is −18.1 dBi.