Industrial , Scientific And Medical Research Articles

Conformal multi-channel MIMO antenna for implantable leadless transcatheter pacing systems

This article presents a conformal multi-channel multiple-input-multiple-output (MIMO) antenna designed for a leadless transcatheter pacing system (TPS), operating across the medical implants communications services (MICS) band (401–406 MHz), the wireless medical telemetry services (WMTS) bands (0.608 GHz and 1.4 GHz), and the industrial, scientific and medical (ISM) bands (0.433 GHz, 0.915 GHz, and 2.45 GHz). The proposed antenna has a size of 19 mm × 10 mm × 0.068 mm (0.047λg × 0.025λg × 0.0001λg), and it is constructed on a thin polyimide substrate and wrapped around the TPS capsule’s inner wall, efficiently utilizing the inner space. For the simulation, the proposed antenna and TPS capsule containing dummy electronics are positioned within a homogeneous three-layered phantom (skin-fat-heart) with dielectric properties that mimic the human heart, as well as in a realistic heterogeneous voxel model (Gustav). The antenna is validated for a real environment using an ex-vivo setup comprised of fabricating the antenna prototype and measuring its performance metrics inside pork meat and phantom solution. The proposed MIMO antenna offers good isolation (>25 dB) between antenna elements, and the impedance bandwidths are 710 MHz (0.34 to 1.05 GHz), 560 MHz (1.26 to 1.82 GHz), and 990 MHz (2.01 to 3 GHz). Further, MIMO characteristics are evaluated, and antenna robustness and safety are tested by considering specific absorption rates using human voxel models. The proposed MIMO antenna is the thinnest conformal antenna designed to cover essential biotelemetry frequency bands, including low frequencies of 0.402 GHz and 0.433 GHz with circular polarization, which significantly reduces power consumption and improves transmission range, making it a viable candidate for wireless TPS applications.

An Ultra‐Thin Dual‐Polarized Bandpass Frequency Selective Surface for 2.45‐/5.8‐GHz ISM Bands

ABSTRACTThis paper presents the design of a single‐layer, double‐sided frequency selective surface (FSS) with bandpass characteristics at the S‐band (2.45 GHz) and C band (5.8 GHz) for sub‐6‐GHz Industrial Scientific and Medical (ISM) bands. The proposed FSS is based on the concept of complementary FSS that produces additional resonant modes. The FSS is constructed using an ultra‐thin microwave laminate with a thickness of 0.00076λeff calculated at the C‐band. The solid patch on the front side of the FSS unit cell is composed of an octagonal ring connected to four spiral arms while the slotted region on the rear side is complementary to the geometry on the front side. The unit cell size of the proposed FSS element is 0.087λeff × 0.087λeff. The FSS has an ultra‐low profile with at least 40% size reduction compared to the state‐of‐the‐art. The FSS element offers 11.12% (288 MHz) and 11.45% (650 MHz) at 2.45 GHz and 5.8 GHz, respectively, at x‐polarization while 5.8% (142 MHz) and 5.9% (342 MHz) bandwidth in the y‐polarization. The FSS element has a rotational symmetric structure offering enhanced polarization stability and angular independent operation for oblique incidences up to 80°. Furthermore, FSS operation is stable, which is evaluated and presented. The prototype bandpass FSS is fabricated, and the simulation results are validated in real‐time using experiments.

Microwave Technique for Linear Skull Fracture Detection-Simulation and Experimental Study Using Realistic Human Head Models.

Microwave (MW) sensing is regarded as a promising technique for various medical monitoring and diagnostic applications due to its numerous advantages and the potential to be developed into a portable device for use outside hospital settings. The detection of skull fractures and the monitoring of their healing process would greatly benefit from a rapidly and frequently usable application that can be employed outside the hospital. This paper presents a simulation- and experiment-based study on skull fracture detection with the MW technique using realistic models for the first time. It also presents assessments on the most promising frequency ranges for skull fracture detection within the Industrial, Scientific and Medical (ISM) and ultrawideband (UWB) ranges. Evaluations are carried out with electromagnetic simulations using different head tissue layer models corresponding to different locations in the human head, as well as an anatomically realistic human head simulation model. The measurements are conducted with a real human skull combined with tissue phantoms developed in our laboratory. The comprehensive evaluations show that fractures cause clear differences in antenna and channel parameters (S11 and S21). The difference in S11 is 0.1-20 dB and in S21 is 0.1-30 dB, depending on the fracture width and location. Skull fractures with a less than 1 mm width can be detected with microwaves at different fracture locations. The detectability is frequency dependent. Power flow representations illustrate how fractures impact on the signal propagation at different frequencies. MW-based detection of skull fractures provides the possibility to (1) detect fractures using a safe and low-cost portable device, (2) monitor the healing-process of fractures, and (3) bring essential information for emerging portable MW-based diagnostic applications that can detect, e.g., strokes.

Circuit modelling and validating a capacitively loaded implantable antenna with its sensitivity analysis for biomedical applications

This paper presents a flexible and capacitively loaded implantable antenna with its sensitivity analysis for biomedical applications. The proposed antenna is designed to operate within the ISM (Industrial, Scientific, and Medical) band, which ranges from 2.4 to 2.48 GHz. The overall dimensions of an antenna are 8 × 8 × 0.25 mm3. The substrate material FR-4 is utilised with a dielectric constant (ε r) 4.4, loss tangent (δ) 0.0022 and a thickness of 0.25 mm for the proposed antenna. An ultra-flexible superstrate material, Parylene C, is used with a thickness of 40 microns on both sides of an antenna to avoid direct contact of metallization with human tissue. Further, the proposed antenna is initially implanted inside a four-layer cubic (FLC) phantom, and then its parameters are validated using the CST Hugo voxel model. The simulated bandwidth of an antenna is 28.16 %, whereas measured bandwidths are 32.25 % inside the tissue-mimicking phantom and 64 % inside minced pork. Moreover, assessing the specific absorption rate (SAR) in a realistic model ensures patient safety by following the guidelines outlined in C95.1–1999 for 1g and 10g of tissue. The simulated and measured results are in close agreement, making the designed antenna appropriate for biomedical applications.

Analysis, design, and optimization based on genetic algorithms of a highly efficient dual-band rectenna system for radiofrequency energy-harvesting applications

This paper gives an enhanced Rectenna design that operates at dual-band [2.45 and 5.8] GHz in the ISM (Industrial, Scientific, and Medical) band and is printed on an FR4-Epoxy substrate. This Rectenna design includes two proposed sub-designs for the receiving antenna and rectifier circuit based on the microstrip technology. The first sub-design concerns the microstrip patch antenna (MPA) described by its radiating element as a pentagonal, its ground being affected by a defective ground structure technique, and its polarization manner as circular polarization. This MPA design is analyzed, designed, optimized using genetic algorithms (GAs), simulated under CST MWS (i.e., computer simulation technology microwave studio), and confirmed by another software named HFSS (high-frequency structure simulator). The second sub-design concerns the microstrip rectifier circuit (MRC) that contains an input matching network based on a coupled-line impedance transformer strategy to achieve good adaptation between MPA and MRC, voltage doubler converter using an SMS7630 Schottky diode thanks to its high sensitivity, microstrip interdigital capacitor to mitigate the intrinsic losses due to the lumped elements, harmonic rejection filter based on a stepped-impedance low-pass filter to reject the unwanted harmonics generated by the non-linear behavior of SMS7630, and the resistive load that models the consumption of the system to be fed. This MRC is analyzed, designed, optimized using GAs, and simulated under ADS (Advanced Design System). The effectiveness of the proposed MPA is proven in terms of gain equals 3.06 dBi and 4.683 dBi at 2.45 GHz and 5.8 GHz respectively, and efficiency equals 95.13 % and 96.552 % at 2.45 GHz and 5.8 GHz respectively. The proposed MRC is effective in terms of efficiency at a lower input power value of about 97.18 % and 67.93 % at 2.45 GHz and 5.8 GHz respectively.

A series‐fed frequency scanning antenna for millimeter wave wireless communication

AbstractIn the realms of 5G and the upcoming 6G communications, the millimeter‐wave bands offer substantially greater bandwidth. However, due to their propagation characteristics, aligning antennas becomes a challenging issue, particularly at the node side in industrial and vehicular network applications. Angle‐scanning antennas can significantly enhance communication reliability or provide new possibilities for spatial multiplexing. Previous studies have predominantly concentrated on frequency‐scanning antennas characterized by either low‐gain individual units or expensive digital arrays. Consequently, there has been a scarcity of solutions that are both cost‐effective and high‐gain. In this study, a method is proposed for achieving frequency scanning by extending the feed lines between elements. Based on this approach, a millimeter‐wave high‐gain serial‐feed frequency‐scanning antenna is developed. This antenna operates within the 60–64 GHz millimeter‐wave ISM (Industrial, Scientific, and Medical) band and is capable of performing a 10 scan in the E‐plane. Moreover, the antenna maintains a width of less than half a wavelength, allowing for the assembly of multiple antennas into a MIMO array.

Analysis of tumor detection using polydimethylsiloxane based wearable antenna

Abstract A Polydimethylsiloxane (PDMS) based antenna is designed for skin tumor detection. The antenna functions at 2.45 GHz with a bandwidth of 2.30–2.64 GHz working in the ISM (Industrial, Scientific, and Medical) band. The size of the antenna is 40 × 40 × 1 mm3. This antenna detects tumors in the skin by considering the variations in values of the E-field, J-surf, and H-field. Various analyses such as the distance between the patch and stacked layer skin phantom for different tumor sizes and input power to the antenna are changed and antenna performance is observed. A significant amount of changes is attained which denotes the presence of the tumor. The proposed antenna is fabricated and the corresponding results are analyzed in the Anechoic Chamber. The antenna has an efficiency of 99 % with a Specific Absorption Rate of 1.3846 W/kg which is lower than 1.6 W/kg as per the recommendations of FCC standard.

Design of a Novel Wearable Textile Antenna for Enhanced Performance in Medical and Wireless Applications

Wearable textile antennas have gained significant attention in recent years due to its growing demand.They are portable and integrating these antennas into textiles enhance wearability and comfort. In this project we explore the design and optimization of a horn-shaped wearable textile antenna for resonance in the ISM (Industrial, Scientific, and Medical) band and diverse commercial wireless applications.The antenna will be designed on a jeans substrate with a relative permittivity (εr) of 1.6 and having physical dimensions of 50×80×0.56 mm3. In terms of performance, the proposed antenna will be analyzed by observing the parameters like Return loss,Gain and VSWR.These wearable antennas are used in medical field to remotely monitor the blood pressure,heart rate and temperature of the patient.This antenna also works for WiFi,WiMAX,ISM and C-band applications.The desired antenna will be simulated using CST Microwave Studio. . Keywords— Microstrip patch antenna, ISM band, Multiband.

Analysis of muscle implanted antenna performance with the variation of implantation depth

Abstract Implantation depth of Implantable Medical Devices (IMDs) is an important factor of communication quality between implantable antennas in IMDs and external devices. Therefore, it is required to study the effect of implantation depth on implantable antenna performance. In this article, dependence of resonant frequency and scattering parameters of a two-antenna system where one miniaturized meander-line antenna is placed within human muscle tissue layer operating at 2.45 GHz ISM (industrial, scientific and medical) band and a rectangular patch antenna placed outside human body, are tested. Here 15 values of implantation depth ranging over 5–35 mm inside muscle layer are taken and for each case resonant frequency and scattering parameters (S 11 and S 21) of the system are recorded. Statistical analysis has been performed to observe how these performance parameters are dependent on depth of implantation which may be varied at the time of surgery.

Genetic Algorithm for Mode Selection in Device-to-Device (D2D) Communication for 5G Cellular Networks

The widespread use of smart devices and mobile applications is leading to a massive growth of wireless data traffic. With the rapidly growing of the customers’ data traffic demand, improving the system capacity and increasing the user throughput have become essential concerns for the future fifth-generation (5G) wireless communication network. In a conventional cellular system, devices are not allowed to directly communicate with each other in the licensed cellular spectrum and all communications take place through the base stations (BS) and core network. Device-to-Device (D2D) communication refers to a technology that enables devices to communicate directly with each other, without sending data to the base station and the core network. This technology has the potential to improve system performance, enhance the user experience, increase spectral efficiency, reduce the terminal transmitting power, reduce the burden of the cellular network, and reduce end to end latency. In D2D communication user equipment’s (UEs) are enabled to select among different modes of communication which are defined based on the frequency resource sharing. Dedicated mode where D2D devices directly transmit by using dedicated resources. Reuse mode where D2D devices reuse some resources of the cellular network. Outband mode where D2D communication uses unlicensed spectrum (e.g. the free 2.4 GHz Industrial Scientific and Medical (ISM) band or the 38 GHz millimetre wave band) where cellular communication does not take place. Cellular mode where the D2D communication is relayed via gNode B (gNB) and it is treated as cellular users. In this work, the target was to reach the optimal mode selection policy and genetic algorithm method was used with the objective of maximizing the total fitness function. Optimal mode selection policy was presented and analysed amongst cellular, dedicated, reused and outband mode. In the present study of mode selection issues in D2D enabled networks, genetic algorithm was proposed for the case when the cellular user equipment (UE) moves in the network. Quality of service (QoS) parameters, mobility parameters and Analytic Hierarchy Process (AHP) method were used to define the mode selection algorithm. To evaluate the performance of the proposed genetic algorithm, a study of the convergence of the algorithm and the signal-to-interference plus noise ratio (SINR) was done.

Design and performance analysis of an L-shaped radiator and defected ground antenna for enhancing wireless connectivity in brain implants

Brain implantable wireless microsystems has potential to treat neurological diseases and maintain the quality of life. Highly efficient miniaturized antenna is the fundamental part of BID (brain implantable device) for reliable signaling of data through dissipative intracranial material. In this paper, a patch antenna with L-shaped defected ground is demonstrated. L-shaped radiator contributed to achieve the resonance at 2.45 GHz industrial scientific and medical (ISM) band. Antenna size is reduced to 10 × 10 × 0.25 mm3. The proposed L-shaped ground plane geometry is contributing in improving the radiation performance. |S11| value shifts from 15 dB to 30 dB after modifying the ground plane. Proposed structure attained the gain of −14 dBi when located between the Dura and CSF layers at the depth of 12 mm in human brain model. Full wave simulated antenna prototype is fabricated and measured for performance verification. Impedance bandwidth of 270 MHz and broadside radiation pattern (for transferring maximum electromagnetic energy away from tissue) are maintained by the proposed antenna. Brain tissue safety is ensured by specific absorption rate which is 0.709 W/kg and in compliance with the safety limits of 1.6 W/kg for 1-g averaged tissue. Proposed antenna structure is the promising candidate for medical implant technology.

A Spiral Flower Shape Wearable Antenna for Smart Internet of Things Applications

In this paper a small patch antenna is proposed for smart wearable internet of things applications. The antenna is proposed to be the main piece of a In this paper a small patch antenna is proposed for smart wearable internet of things (IoT) applications. The antenna is proposed to be the main piece of a necklace. It works for the 2.4 - 2.5 GHz industrial, scientific and medical (ISM) band. It also works for other bands such as 5.564 - 5.65 GHz, 6.79 - 6.973 GHz, 7.7614 - 7.883 GHz and 8.5 - 8.65 GHz with a small size of 40 × 50 mm2 and robust performance. The proposed design showed to have many appealing features such as small size, conformity and multi-band functionality and, thus, it could be a good candidate for IoT wearables.

A Contact-Less Electrically Small Antenna Sensor for Retinal Cancer Cell Detection

A new noninvasive and portable diagnostic system for detecting ocular tumors has been proposed. The system uses a contact-less electrically small antenna sensor to detect retinal cancer cells. The antenna sensor is operated in the ISM (Industrial, Scientific, and Medical) 2.413 GHz band and has electrical dimensions of 8 × 16.2 × 0.35 mm3. The antenna sensor is fabricated on a biodegradable Teslin substrate and tested in an eye-mimicking phantom to compare numerical computations with measurements. The specific absorption rate (SAR) obtained at near and far-field distances under 1 g of tissue is 1.18 W/kg and 0.353 W/kg, and that under 10 g of tissue is 0.112 W/kg and 0.313 W/kg, respectively. Furthermore, to detect the ocular tumor using the proposed antenna sensor, the resonance frequency shift, and the unsupervised machine learning technique, principle component analysis (PCA) is employed on simulated and measured results. The resonance frequency shift for a 3.5 mm radius tumor is 70 MHz for a single tumor and 120 MHz for double tumors. The PCA generates clusters with and without tumors on the positive and negative sides of the two-dimensional plot. The proposed techniques are more impactful in distinguishing between healthy and malignant tissues. The proposed systematic approach could be a portable platform for early detection of cancerous cells inside the eye.

LoRa Communication Using TVWS Frequencies: Range and Data Rate

Low power wide area network (LPWAN) is a wireless communication technology that offers large coverage, low data rates, and low power consumption, making it a suitable choice for the growing Internet of Things and machine-to-machine communication applications. Long range (LoRa), an LPWAN technology, has recently been used in the industrial, scientific and medical (ISM) band for various low-power wireless applications. The coverage and data rate supported by these devices in the ISM band is well-studied in the literature. In this paper, we study the usage of TV white spaces (TVWS) for LoRa transmissions to address the growing spectrum demand. Additionally, the range and data rate of TVWS-based LoRa, for different transmission parameter values using different path-loss models and for various scenarios such as free space, outdoor and indoor are investigated. A path-loss model for TVWS-based LoRa is also proposed and explored, and the evaluations show that TVWS offers a longer range. This range and data rate study would be useful for efficient network planning and system design for TVWS-based LoRa LPWANs.

Pattern-Reconfigurable Flexible Textile Antenna Using RF-Switch Integrated Circuits

A pattern-reconfigurable flexible textile antenna covering the 2.45 GHz Industrial, Scientific and Medical (ISM) band is presented. The design utilizes RF-switch Integrated Circuits (ICs) packaged into reconfiguration modules as switchable vias to change between the omnidirectional and broadside radiation modes of a center-shorted patch. Analytical models to calculate the resonance frequency of each mode are developed to give more physical insights into the mode resonance and assist the design optimization. An antenna prototype is experimentally characterized to further validate the concept and analysis of the proposed antenna structure. The stable performance under on-body environment and various bending test conditions demonstrates the antenna operation in wearable scenarios.

A Simple Technique for Liquid–Liquid Percentage Determination Using Single-Frequency Amplitude Measurements

This letter presents a novel technique for the liquid–liquid percentage reading based on the measurement of the transmission amplitude at a single frequency in a cavity resonator with a small pipe where the liquids flow. The proposed approach represents an alternative to the conventional technique based on the determination of the resonance frequency shift and presents a number of advantages. First of all, the proposed technique requires just an oscillator and a power meter at a fixed frequency, instead of the complex equipment needed for the broadband measurement of the scattering parameters of the circuit, as in the conventional technique. Consequently, the proposed method is well-suited for the implementation of low-cost embedded sensors. Moreover, by avoiding the frequency sweep, the reading is instantaneous and therefore the real-time determination of the characteristics of flowing liquids is possible. Experimental results have been performed with a substrate-integrated waveguide (SIW) cavity operating around the frequency of 2.48 GHz industrial scientific and medical (ISM) band, by comparing the performance of the proposed approach and the conventional one in the determination of the liquid–liquid percentage of mixtures of acetone and isopropanol.

Bio-based substrate for flexible electronics - application to a 2.45 GHz wearable patch antenna

In this paper, a bio-based and biocompatible polymer, Cellulose Laurate (CL), is proposed for flexible radio-frequency (RF) electronics. The synthesis of CL films together with their characterizations (chemical, thermal, mechanical and dielectric) are presented. The results obtained allow considering this material for RF flexible applications as a possible alternative to petrosourced substrates. Therefore, CL has been used to fabricate a flexible patch antenna that operates in an industrial, scientific and medical (ISM) frequency band. The central frequency selected is 2.45 GHz. The antenna fabrication process is based on the combination of laser structuring and the use of copper adhesive tape. Measurements of the antenna reflection coefficient and radiation patterns show that CL is a good candidate as a RF substrate. Furthermore, it is demonstrated that the antenna performance is only slightly impacted under bending conditions.

A High Performance All-Textile Wearable Antenna for Wristband Application.

A compact, conformal, all-textile wearable antenna is proposed in this paper for the 2.45 GHz ISM (Industrial, Scientific and Medical) band. The integrated design consists of a monopole radiator backed by a 2 × 1 Electromagnetic Band Gap (EBG) array, resulting in a small form factor suitable for wristband applications. An EBG unit cell is optimized to work in the desired operating band, the results of which are further explored to achieve bandwidth maximization via floating EBG ground. A monopole radiator is made to work in association with the EBG layer to produce the resonance in the ISM band with plausible radiation characteristics. The fabricated design is tested for free space performance analysis and subjected to human body loading. The proposed antenna design achieves bandwidth of 2.39 GHz to 2.54 GHz with a compact footprint of 35.4 × 82.4 mm2. The experimental investigations reveal that the reported design adequately retains its performance while operating in close proximity to human beings. The presented Specific Absorption Rate (SAR) analysis reveals 0.297 W/kg calculated at 0.5 W input power, which certifies that the proposed antenna is safe for use in wearable devices.

Dual-Band Antenna on 3D-Printed Substrate for 2.4/5.8 GHz ISM-Band Applications

In this paper, we present a dual-band antenna working at 2.45 GHz and 5.8 GHz. The design is based on two radiating rectangular slots with one upper Split Ring Resonator (SRR) to enhance the radiation pattern at 5.8 GHz, one Complementary Split Ring Resonator (CSRR), and three Split Rings (SR) to improve the input reflection coefficient. The dual-band antenna covers the 2.45 GHz and 5.8 GHz Industrial, Scientific and Medical (ISM) bands. The total size of the proposed antenna is 31 × 70 × 70 mm3. The proposed antenna was manufactured and tested. The attained gain is better than 7.5 dBi, and 6.5 dBi at 2.4 GHz and 5.8 GHz, respectively. The measured gain and input reflection coefficient have good correlation with the simulated results, covering the ISM bands around 2.45 GHz and 5.8 GHz. The performance of the proposed antenna is remarkable and suitable for applications where the size is not a severe limitation, such as sensors, LPWAN/WLAN modules, health care devices, base stations, IoT, and control applications.

A planar microwave sensor for noninvasive detection of glucose concentration using regression analysis

AbstractThis paper presents a planar microwave sensor for the noninvasive detection of glucose concentration in diabetic patients. The designed sensor operates from the 3.8 to 6.2 GHz frequency band, which covers the 5.8 GHz Industrial Scientific and Medical (ISM) band. The designed sensor shows a percentage bandwidth of 23.8% with a reflection coefficient (S11) of −50 dB at the resonance frequency of 5.7 GHz. The detection was carried out by varying the relative permittivity of the blood in accordance with the glucose concentration based on the Cole–Cole model. The measured result is calculated in terms of varying resonance frequency with variation in the reflection coefficient |S11| of the designed sensor. The observed frequency shift and corresponding sensitivity of the sensor are found at 1.7 GHz and 0.089 MHz/mg dL−1, respectively. An experimental validation has also been performed, and the frequency shift is analyzed by interacting the human thumb with the sensor. The simulated and experimental results of the designed sensor suggest that it can be useful for detecting glucose concentration noninvasively for diabetic patients.