Specific Absorption Rate Values Research Articles

A highly miniaturized antenna with wider band for biomedical applications

ABSTRACT A highly miniaturized planar monopole antenna is presented for biomedical applications. The proposed antenna utilizes polydimethylsiloxane (PDMS) with dielectric constant 2.7 and loss tangent 0.0314 with thickness 0.3 mm as substrate and with thickness 0.2 mm as superstrate. A copper foil of 0.03 mm thickness is used for radiating elements. The proposed structure contains a unique structure, made of loop-based structure with three rectangular-shaped stubs are added to tune the operating frequency to 5.8 GHz and to improve the reflection coefficient. The incorporation of stubs achieved the intended frequency of operation, utilization of the loop-based structure for designing the antenna achieved high miniaturization. The proposed antenna is analyzed under various conditions like under skin, muscle, stomach, small intestine,, colon etc., and comparative analysis is presented with the help of reflection coefficient, radiation patterns and specific absorption rate (SAR). SAR is evaluated over a volume of 1 g tissue as per the standards of Federal Communications Commission (FCC). SAR value of the antenna is below 1.6 W/kg for input power 1.9 mW. The simulated analysis showed that the designed antenna is suitable for both implantable and endoscopic applications. Moreover the simulated and measured analysis for reflection coefficient of the proposed antenna showed good agreement.

Synthesis, characterization and heating efficiency of Gd-doped maghemite (γ-Fe2O3) nanoparticles for hyperthermia application

In this paper, sol-gel technique was used to prepare Gd-doped γ-Fe2O3 nanoparticles and their heating efficiency for magnetic hyperthermia application was investigated. The obtained nanoparticles are characterized by several techniques. The structural properties are performed by X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDAX) and X-ray Photoelectron Spectroscopy (XPS), while the morphology is investigated by Transmission electron microscopy (TEM). The magnetic properties and heating ability under an alternating magnetic field are performed by vibrating sample magnetometer (VSM) and magnetherm respectively. XRD, XPS and TEM results confirmed the maghemite (γ-Fe2O3) phase, the presence of Gd ions and crystallinity. VSM hysteresis loops showed a negligible coercive field and remanence suggesting superparamagnetic behavior, which was also confirmed by Langevin method. Heating efficiency under an AC alternating magnetic field measurements showed that doped and un-doped samples display high heating ability and reached magnetic hyperthermia (42 °C) in relatively short times with shorter time (∼2 min) observed for γ-Fe2O3 compared to 6 min for Gd (5%) doped γ-Fe2O3 nanoparticles. The specific absorption rate (SAR) values decreased with increased concentration of Gd but remain considerable for all doped samples (up to 40W/g for Gd (5%)). The high crystallinity, superparamagnetic behavior and good SARs values make these nanoparticles a promising candidate for hyperthermia application.

Wearable Textile Antenna with a Graphene Sheet or Conductive Fabric Patch for the 2.45 GHz Band

Textile patch antennas of simple rectangular, triangular, and circular shape, for operation in the 2.4–2.5 GHz free industrial, scientific, and medical (ISM) band, are designed in this paper. Thirty-six patch antenna prototypes have been fabricated by engaging different patch geometries, patch materials, and substrate materials. Each patch antenna is designed after optimization by a genetic algorithm, which evolves the initial dimensions and feeding position of the prototype’s microstrip counterpart to the final optimal geometrical characteristics of the wearable prototype (with the originally selected shape and materials). The impact of the design and fabrication details on antenna performance were thoroughly investigated. Graphene sheet patches were tested against conductive fabric and copper sheet ones, while denim and felt textile substrates were competing. The comparative study between a large number of different graphene, all, and copper textile prototypes, which revealed the excellent suitability of graphene for wearable applications, is the main contribution of this paper. Additional novelty elements are the compact, flexible, and easy-to-fabricate structure of the proposed antennas, as well as the use of state-of-the-art conductive materials and commercially available fabrics and the extensive investigation of many prototypes in various bending conditions. Simulations and measurements of the proposed antennas are in very good agreement. All fabricated prototypes are characterized by flexibility, light weight, mechanical stability, resistance to shock, bending and vibrations, unhindered integration to clothes, low-cost implementation, simple, time-saving, and industry-compatible fabrication process, and low specific absorption rate (SAR) values (computed using rectangular and voxel models); the graphene prototypes are additionally resistant to corrosion, and the circular ones have very good performance under bending conditions. Many antenna prototypes demonstrate interesting characteristics, such as relatively wide bandwidth, adequate gain, firm radiation patterns, coverage of the ISM band even under bending, and very low SAR values. For example, the circular graphene patch (with 55.3 mm diameter attached upon a 165.9 × 165.9 mm) felt substrate CGsF1 prototype accomplishes 109 MHz measured bandwidth, 5.45 dBi gain, 56% efficiency, full coverage of the ISM band under bending, and SAR less than 0.003 W/Kg.

Design and Dosimetric Characterization of a Broadband Exposure Facility for In Vitro Experiments in the Frequency Range 18-40.5 GHz.

A novel exposure facility for exposing cell monolayers to centimeter and millimeter waves (18-40.5 GHz) used by future 5G mobile communication technology and similar applications has been developed. A detailed dosimetric characterization of the apparatus for frequencies of 27 and 40.5 GHz and 60 mm petri dishes, used in a presently ongoing study on human dermal fibroblasts and keratinocytes, was carried out. The exposure facility enables a well-defined, randomized, and blinded application of sham exposure and exposure with selectable values of incident power flux density, and additionally provides the possibility of continuous monitoring of the sample temperature during exposure while it does not require significant deviations from routine in vitro handling procedures, i.e. petri dishes are not required to be placed inside waveguides or TEM cells. Mean specific absorption rate (SAR) values inside the cell monolayer of 115 W/kg (27 GHz) and 160 W/kg (40.5 GHz) per watt antenna input power and corresponding transmitted power density (St ) values at the bottom of the cell monolayer of 65 W/m2 (27 GHz) and 70 W/m2 (40.5 GHz) per watt antenna input power can be achieved, respectively. For reasonable amounts of harvested cells (80% of petri dish bottom area), the variation (max/min) of SAR and St over the cell monolayer remains below 3.7 dB (27 GHz) and 3.0 dB (40.5 GHz), respectively. © 2021 Bioelectromagnetics Society.

Numerical simulation of the radiofrequency safety of 128-channel hd-EEG nets on a 29-month-old whole-body model in a 3 Tesla MRI.

This study investigates the radiofrequency (RF) induced heating in a pediatric whole-body voxel model with a high-density electroencephalogram (hd-EEG) net during magnetic resonance imaging (MRI) at 3 Tesla. A total of three cases were studied: no net (NoNet), a resistive hd-EEG (NeoNet), and a copper (CuNet) net. The maximum values of specific absorption rate averaged over 10g-mass (10gSAR) in the head were calculated with the NeoNet was 12.51 W/kg and in the case of the NoNet was 12.40 W/kg. In contrast, the CuNet case was 17.04 W/Kg. Temperature simulations were conducted to determine the RF-induced heating without and with hd-EEG nets (NeoNet and CuNet) during an MRI scan using an age-corrected and thermoregulated perfusion for the child model. The results showed that the maximum temperature estimated in the child's head was 38.38 °C for the NoNet, 38.43 °C for the NeoNet, and 43.05 °C for the CuNet. In the case of NeoNet, the maximum temperature estimated in the child's head remained compliant with IEC 60601 for the MRI RF safety limit. However, the case of CuNet estimated to exceed the RF safety limit, which may require an appropriate cooling period or a hardware design to suppress the RF-induced heating.

Aqueous synthesis of magnetite nanoparticles for magnetic hyperthermia: Formation mechanism approach, high water-dispersity and stability

Superparamagnetic iron oxide nanoparticles (SPIONs) are interesting for biomedical applications in cancer treatment via magneto-hyperthermia. Its potential application contrasts with the challenges in producing systems with chemical and morphological uniformity and colloidal stability using simple, low-cost, and sustainable routes. Aqueous syntheses usually fail to control morphology and composition because SPIONs formation mechanisms are not fully understood. Here, we propose an aqueous route to synthesize SPIONs based on the controlled and stoichiometric reduction in situ of Fe 3+ to Fe 2+ ions in the presence of sulfite ions, followed by aging at 90 ∘ C in an alkaline medium for 18 h. SPIONs with high water-stable and controlled characteristics in a sustainable, inexpensive, and scalable procedure were obtained. The nucleation, growth, and hydrolysis rates were adjusted by the excess of OH − ions, initial temperature, and iron precursor nature. The results are discussed concerning concepts of the classical and nonclassical nucleation theories, indicating an optimum pH of 9.5–10.5 for SPIONs formation. The SPIONs present an average size of 11 nm, narrow size distribution, and magnetite phase with about 34 mol% of maghemite due to structural defects. Nanoparticles are superparamagnetic, have a hydrodynamic diameter of 130 nm with a surface potential of ~ −40 mV (pH ≥ 7), and suitable magneto-hyperthermic properties fro cancer treatment. Specific Absorption Rate values were evaluated concerning the SPIONs physical-chemical properties, indicating a strong dependence on the average crystallite size and the magnetization at 250 Oe. Cell viability tests showed that SPIONs did not provide any significant change in cellular growth at used concentrations.

Internal Electric Field Reconstruction and SAR Estimation of In-Body Antenna Using Inverse Equivalent Current Method

In this article, we reconstruct the internal electric field due to a dipole antenna embedded in a dielectric phantom for developing a noninvasive specific absorption rate (SAR) measurement system. The reconstruction method is based on the surface equivalent theorem and boundary conditions, which relate the external field radiated from the embedded antenna to equivalent electromagnetic surface currents on the human body. The electric field data sampled at spatial points on a surface enclosing the phantom are used in the inverse calculation. All field integrals are discretized and numerically solved to obtain the electromagnetic currents on the phantom's surface. The internal electric field distribution and SAR value in a phantom can be calculated from the reconstructed surface currents if the electric properties of the phantom are known. The validity of the method was demonstrated numerically and experimentally using a dipole antenna embedded in the lossy rectangular phantom, which has a dielectric constant close to human skin tissue at 2.5 GHz. Comparison with forward numerical simulations has shown that the surface current and electric field distribution can be predicted with great precision. Carefully performing the experiments using a self-made phantom validated our numerical demonstration and provided satisfactory reconstruction results.

A Symmetrical Closed-Loop Conformal Antenna With Wideband for Capsule Endoscope

A symmetrical closed-loop conformal antenna is designed for capsule endoscope at wireless medical telemetry service (608–614 MHz) band and industrial, scientific, and medical (902–918 MHz and 2.4–2.4835 GHz) band. The antenna is compartmentalized into two loops with an inverted-Ω loop and a hollow-T loop by the differential feeding. The antenna has a wideband (| <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | < −10 dB) covering 0.47–1.14 GHz and 1.38–3 GHz. The omnidirectional radiation pattern of the antenna is verified by measurement, and the peak gains are (−15.5, −16.8, and −23.1) dBi for the (611, 915, and 2400) MHz designs, respectively. The antenna possesses excellent environmental tolerance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> environment test. Moreover, the specific absorption rate value of the antenna can satisfy the IEEE regulations under the limit of 2.42 mW net-input power.

Machine Learning-Based Prediction of MRI-Induced Power Absorption in the Tissue in Patients With Simplified Deep Brain Stimulation Lead Models

Interaction of an active electronic implant such as a deep brain stimulation (DBS) system and MRI RF fields can induce excessive tissue heating, limiting MRI accessibility. Efforts to quantify RF heating mostly rely on electromagnetic (EM) simulations to assess individualized specific absorption rate (SAR), but such simulations require extensive computational resources. Here, we investigate if a predictive model using machine learning (ML) can predict the local SAR in the tissue around tips of implanted leads from the distribution of the tangential component of the MRI incident electric field, Etan. A dataset of 260 unique patient-derived and artificial DBS lead trajectories was constructed, and the 1 g-averaged SAR, 1gSARmax, at the lead-tip during 1.5 T MRI was determined by EM simulations. Etan values along each lead's trajectory and the simulated SAR values were used to train and test the ML algorithm. The resulting predictions of the ML algorithm indicated that the distribution of Etan could effectively predict 1gSARmax at the DBS lead-tip (R = 0.82). Our results indicate that ML has the potential to provide a fast method for predicting MR-induced power absorption in the tissue around tips of implanted leads such as those in active electronic medical devices.

Maghemite (γ-Fe2O3) and γ-Fe2O3-TiO2 Nanoparticles for Magnetic Hyperthermia Applications: Synthesis, Characterization and Heating Efficiency.

In this report, the heating efficiencies of γ-Fe2O3 and hybrid γ-Fe2O3-TiO2 nanoparticles NPs under an alternating magnetic field (AMF) have been investigated to evaluate their feasible use in magnetic hyperthermia. The NPs were synthesized by a modified sol-gel method and characterized by different techniques. X-ray diffraction (XRD), Mössbauer spectroscopy and electron microscopy analyses confirmed the maghemite (γ-Fe2O3) phase, crystallinity, good uniformity and 10 nm core sizes of the as-synthesized composites. SQUID hysteresis loops showed a non-negligible coercive field and remanence suggesting the ferromagnetic behavior of the particles. Heating efficiency measurements showed that both samples display high heating potentials and reached magnetic hyperthermia (42 °C) in relatively short times with shorter time (~3 min) observed for γ-Fe2O3 compared to γ-Fe2O3-TiO2. The specific absorption rate (SAR) values calculated for γ-Fe2O3 (up to 90 W/g) are higher than that for γ-Fe2O3-TiO2 (~40 W/g), confirming better heating efficiency for γ-Fe2O3 NPs. The intrinsic loss power (ILP) values of 1.57 nHm2/kg and 0.64 nHm2/kg obtained for both nanocomposites are in the range reported for commercial ferrofluids (0.2–3.1 nHm2/kg). Finally, the heating mechanism responsible for NP heat dissipation is explained concluding that both Neel and Brownian relaxations are contributing to heat production. Overall, the obtained high heating efficiencies suggest that the fabricated nanocomposites hold a great potential to be utilized in a wide spectrum of applications, particularly in magnetic photothermal hyperthermia treatments.

Compact Power-Symbol Shaped Microstrip Antenna for Healthcare Monitoring Systems

In this study, a microstrip patch antenna is presented to be used in biomedical systems and applications, that has an operating frequency covering the Industrial Scientific and Medical (ISM) band (2.4-2.5 GHz). The size of the proposed implantable medical antenna is 28 mm×28 mm×0.62 mm3, where Rogers RO3210 material with a thickness of 0.62 mm has been used as a substrate. The antenna is analyzed under planar and bent conditions inside a three-layer of human tissue (skin, fat and muscle); where the simulations are carried out with the help of CST MWS software program. Finally, the Specific Absorption Rate (SAR) values are assessed to check the amount of harmful electromagnetic fields emitted by the human body. Therefore, the proposed antenna design is convenient to be used in healthcare applications.

PEG Coated Fe3O4/RGO Nano-Cube-Like Structures for Cancer Therapy via Magnetic Hyperthermia.

Superparamagnetic iron oxide nanoparticles (SPIONs) have high saturation magnetization and are promising candidates for hyperthermia. They may act as magnetic heating agents when subjected to magnetic field in nano-based hyperthermia. In this work, cube-like Fe3O4 nanoparticles (labelled as cubic SPIONs) with reduced graphene oxide (RGO) nanocomposites were prepared by a microwave hydrothermal method. The shape and size of magnetic nanoparticles were controlled by varying synthesis parameters, including reaction time, pressure and microwave power. This study successfully synthesized cubic SPIONs nanocomposites with an average particle size between 24–34 nm. Poly-(ethylene) glycol (PEG) was used as a coating material on SPIONs to enhance biocompatibility. The RGO sheets provided a high surface area-to-volume ratio for SPIONs to be dispersed on their surface, and hence, they prevented aggregation of the SPIONs in the nanocomposites. Magnetically induced heating studies on the optimized nanocomposite (Fe3O4/RGO/PEG) demonstrated heating capabilities for magnetic hyperthermia application with a promising specific absorption rate (SAR) value of 58.33 W/g in acidic solution. Cytotoxicity tests were also performed to ensure low nanoparticle toxicity before incorporation into the human body. The results of the standard assay for the toxicity determination of the nanocomposites revealed over 70% cell survival after 48 h, suggesting the feasibility of using the synthesized nanocomposites for magnetic hyperthermia.

A Review on State of Art Techniques of Antennas for Body Area Networks

In this paper, we explore some of the notable research works that will open a new dimension in the field of antenna research applicable to body area networks. Different types of antennas for body area networks include implantable antenna, ingestible pill antenna, and wearable antennas. The antennas for body area networks gained the attention of the researchers after the demands of the compact as well as efficient wearable devices increased. The design of antennas for body area network applications is very interesting and challenging, as a researcher has to ensure that the antenna should have a small footprint, and be flexible. Simultaneously, the radiation must be in a particular direction with a workable gain, and low Specific Absorption Rate (SAR) to avoid damage. These antennas require performing well in proximity to the living bodies that tend to degrade the performance. The antennas that are in demand include implantable antennas, ingestible antennas, on-body antennas, and antennas for off-body communications. In this paper, the earlier works have been analyzed well and verified with a compact CPW-fed circular patch antenna design, backed by a metal conductor. This antenna exhibits the perfect matching at two frequency bands. These are S11 (below -10 dB) bandwidth of 3.4 GHz ranging from 2.45 – 5.89 GHz and an S11 bandwidth of 0.99 GHz ranging from 9.10 – 10.09 GHz. While in contact with the human body, the antenna exhibits a bandwidth of 2.54 GHz between 3.02-5.56 GHz and a bandwidth of 3.01 GHz between 9.8-12.81 GHz. The SAR values are 0.82 W/kg and 0.56 W/kg. The antenna is a suitable candidate for off-body communication in wearable applications.

Preparation and characterization of new nanoparticles compounds based on iron and iodine as prospective materials for medical applications

Developed compounds of magnetic iron iodide nanoparticles (MIINPs) were simply and cheaply prepared for their potential use in the bioapplications through magnetic hyperthermia therapy, using a co-precipitation method based on the study of various factors such as temperature, molar ratio and pH. Two samples of MIINPs were chosen based on the proportions of iron and iodide in the sample, respectively 45 and 55% in MIINPs-1 and 52 and 48% in MIINPs-2. Fourier transforms infrared spectroscopy (FTIR), thermal analysis (TA), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) were used to characterize the prepared compounds. The chemical composition of MIINPs-1 and MIINPs-2 was determined by means of an elemental analysis using EDX technique and confirmed using structural modeling by Visual Minteq 3.0, Match 1.9 and Endeavour 1.7 software. The magnetic properties of both samples were measured and found to be superparamagnetic materials. Both MIINPs-1 and MIINPs-2 samples have approximately the same magnetization (nearly 36.1 emu/g) in the 500 Oe coercive field as safe operating limits for MHT achieving 94% and 86.4% of their saturation values respectively. Specific absorption rates (SARs) were practically and theoretically determined as well as it was found that the practical SAR value of MIINPs-1 is much closer to the theoretical value than in the case of MIINPs-2.

In Vitro Evaluation of Hyperthermia Magnetic Technique Indicating the Best Strategy for Internalization of Magnetic Nanoparticles Applied in Glioblastoma Tumor Cells

This in vitro study aims to evaluate the magnetic hyperthermia (MHT) technique and the best strategy for internalization of magnetic nanoparticles coated with aminosilane (SPIONAmine) in glioblastoma tumor cells. SPIONAmine of 50 and 100 nm were used for specific absorption rate (SAR) analysis, performing the MHT with intensities of 50, 150, and 300 Gauss and frequencies varying between 305 and 557 kHz. The internalization strategy was performed using 100, 200, and 300 µgFe/mL of SPIONAmine, with or without Poly-L-Lysine (PLL) and filter, and with or without static or dynamic magnet field. The cell viability was evaluated after determination of MHT best condition of SPIONAmine internalization. The maximum SAR values of SPIONAmine (50 nm) and SPIONAmine (100 nm) identified were 184.41 W/g and 337.83 W/g, respectively, using a frequency of 557 kHz and intensity of 300 Gauss (≈23.93 kA/m). The best internalization strategy was 100 µgFe/mL of SPIONAmine (100 nm) using PLL with filter and dynamic magnet field, submitted to MHT for 40 min at 44 °C. This condition displayed 70.0% decreased in cell viability by flow cytometry and 68.1% by BLI. We can conclude that our study is promising as an antitumor treatment, based on intra- and extracellular MHT effects. The optimization of the nanoparticles internalization process associated with their magnetic characteristics potentiates the extracellular acute and late intracellular effect of MHT achieving greater efficiency in the therapeutic process.

Nanomaterials for magnetic hyperthermia

Abstract Background Cancer remains as one of the major causes of mortality worldwide. Recent advances in nanoparticles based therapy mark a new era on cancer treatment. Many groups have investigated biological/physical effects of nanoparticles on tumour cells and how these vary with physical parameters such as particle size, shape, concentration and distribution. Magnetic hyperthermia (MHT) can be an alternative or an add-value therapy with demonstrated effectiveness. MHT uses magnetic nanoparticles, which can be directly applied to the tumour, where, by applying an external ac magnetic field, will promote a localized temperature increment that can be controlled. Methods LiFe5O8 nanocrystallites were synthesized by a novel and eco-friendly sol-gel process, using powder coconut water (PCW) has a mediated reaction medium. The dried powders were heat-treated between 400 and 1000 °C, being analysed their structure, morphology and magnetic properties; cytotoxicity and magnetic hyperthermia assays were performed. Results The heat-treated LiFe5O8 powder led to crystallite sizes from 50 nm to 200 nm. Increasing the temperature of the heat treatment, secondary phases tend to disappear. The cytotoxicity results revealed a non-cytotoxicity property, for concentrations below 5 mg/mL. The sample HT at 1000 °C, revealed hysteresis and magnetic saturation of 73 emu.g−1 at 300 K and a specific absorption rate(SAR) of about 80 W/g. Conclusions It was possible to synthesize LiFe5O8 by a novel, eco-friendly and sustainable route. The nanoparticles have a high heat efficiency, especially the sample heat-treated at 1000 °C, with SAR values similar to Fe3O4, showing potential to be used in the treatment of cancer, by MHT.

Analysis of a Compact Multi-Band Textile Antenna for WBAN and WLAN Applications

A dual-band wearable antenna is designed on a textile material. The design operates at ISM bands available for Wireless Body Area Network and Wireless Local Area Network with an input match better than -15 dB. The antenna is designed by using Computational Electromagnetic Software (CEMS) based on finite-difference time-domain (FDTD) method. A three-layer phantom model including skin, fat and muscle has been considered to compute the specific absorption rate (SAR). The maximum value of SAR averaged over 1g and 10g of tissue is less than 1.6 W/Kg and 2 W/Kg, respectively, when the maximum incident power of the antenna is 63 mW. These values are incompliance with the international electromagnetic safety standards.

A pattern‐reconfigurable antenna design for body area networks communications

This article presents a novel pattern-reconfigurable antenna based on theory of characteristic mode for body area networks (BAN) communication. The radiation pattern of the antenna is able to switch between the omnidirectional pattern and broadside pattern, which can satisfy on-body and off-body communication links simultaneously. An array of 4 × 2 rectangular plates with the off-body communication mode at BAN frequency band is used as the main radiator, and four copper posts between the radiator and the ground are introduced to generate the on-body mode. A simple feeding network is designed to selectively excite the two modes. The footprint of the proposed antenna is 0.43 λ0 × 0.43 λ0 × 0.05 λ0. For demonstration, the proposed antenna has been fabricated and measured both in the free space and on the phantom. The measured results agree well with the simulated ones. Furthermore, the issue of the specific absorption rate (SAR) is studied. The peak SAR values of the proposed antenna in two communication modes are far below the Federal Communication Commission standard. In addition, for practical application, the link budget of the on-body link is investigated. The stable impedance and radiation properties, the low SAR values and the reliable communication ability make the proposed antenna be a suitable candidate for BAN communications.

Design of a wide bandwidth and high gain wearable antenna based on nonuniform metasurface

AbstractA metasurface (MS) antenna for the 5 GHz wireless local area network (WLAN) band is presented in this paper. The antenna is feed by a modified aperture‐coupled structure with an optimized rectangular nonuniform MS to widen the bandwidth and improve the gain. The proposed antenna has a thickness of 4 mm and occupies an area of 50 mm × 50 mm. The operating frequency range of the antenna is 4.72–6.19 GHz, covering the 5.15–5.825 GHz band used by the 5 GHz WLAN. The measured average gain is 7.23 dBi. The simulated specific absorption rate values under 1 g and 10 g standard are lower than the limitation of U.S. and European. Due to its simple structure, wide bandwidth and small size, the proposed MS antenna has great potential in the wearable applications.

Influence of Ca doping on ZnFe2O4 nanoparticles magnetic hyperthermia and cytotoxicity study

The biocompatibility nature of the synthesized nanoparticles (NPs) has exposed a superparamagnetic (SP) behavior with best saturation mass magnetization (Ms) values and monodispersed behavior. All these characteristics are essential, for their importance as nanomedicine in the magnetic hyperthermia (MH) treatment of cancer. The prepared powder samples were validated as capable MH mediators by their heating efficiency as measured by specific absorption rate (SAR) in calorimetric measurements. Three Ca2+ - substituted ZnFe2O4 NPs with different Ca2+ contents, the particle size, and crystallite size of the samples have been prepared. These ideal premises have permitted the investigation of the induction heating aptitudes wholly on the origin of the various chemical compositions. Enhanced magnetic features of prepared NPs initiated us to investigate these systems as capable MH agents. FT-IR spectra confirm that the presence of functional groups and vibrational modes of spinel structure. Composition information of the prepared NPs has been studied by X-ray photoelectron spectroscopy (XPS). The prepared samples have significant Ms values at 15 K (< 80 emu/g). The enhance in the Ca2+ concentration up to x = 0.5 in the structure (sample) has resulted in an enhancement of the Ms at 15 K. The SAR value for the x = 0.5 sample (1 mg/mL) is nearly 6 times greater than that of the x = 0.1 (1 mg/mL) sample. Induction heating profile measurements reveal that the heating efficiency enhances with the enhancing of the ferrofluid concentration. The outcomes obtained in this current work deliver a deep and expressive understanding of the use of prepared NPs for MH cure and pave the route for using such kinds of NPs for upcoming clinical and biomedical applications. In vitro, Prestoblue® assay test analysis from skin fibroblast confirmed the synthesized NPs were biocompatible over 0–1000 μg/mL concentrations. Based on these characterizations suggested that the prepared NPs may be significant potential agents for MH application.