Specific Absorption Rate Values Research Articles

Biocompatible Tb doped Fe3O4 nanoparticles with enhanced heating efficiency for magnetic hyperthermia application

Magnetic hyperthermia has a specific limitation in treating localized and relatively accessible malignant tumors regardless of its promising therapeutic regime. In this present work, Tb doped Fe3O4 magnetic nanoparticles (MNPs) prepared via coprecipitation root and confirmed the structural conformation and phase purity by XRD, FTIR, TEM, and SEM analysis. TGA analysis was carried out for thermal stabilization and to verify the formation of a stable phase. The occupancy of Tb ions at the octahedral sites and cationic distribution can be calculated from Rietveld refinement analysis. The relaxation mechanism, dipolar- dipolar interactions among the particles, and randomly directed magnetic anisotropy axes were investigated by ESR spectroscopy. The magnetic results enumerate that increasing Tb doping concentration leads to increased saturation magnetization and decreased coercivity and retentivity. The self-heating properties of the doped nanoparticles were characterized by measuring specific absorption rate (SAR). The improved saturation magnetization and enriched SAR value enable the doped MNPs for magnetic hyperthermia application with excellent efficacy.

Functionalized SPION immobilized on graphene-oxide: Anticancer and antiviral study

The progressive and fatal outbreak of some diseases such as cancer and coronavirus necessitates using advanced materials to bring such devastating illnesses under control. In this study, graphene oxide (GO) is decorated by superparamagnetic iron oxide nanoparticles (SPION) (GO/SPION) as well as polyethylene glycol functionalized SPION (GO/SPION@PEG), and chitosan functionalized SPION (GO/SPION@CS). Field emission scanning electron microscopic (FESEM) images show the formation of high density uniformly distributed SPION nanoparticles on the surface of GO sheets. The structural and chemical composition of nanostructures is confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. The saturation magnetization of GO/SPION, GO/SPION@PEG and GO- SPION@CS are found to be 20, 19 and 8 emu/g using vibrating sample magnetometer. Specific absorption rate (SAR) values of 305, 283, and 199 W/g and corresponding intrinsic loss power (ILP) values of 9.4, 8.7, and 6.2 nHm2kg−1 are achieved for GO/SPION, GO/SPION@PEG and GO/SPION@CS, respectively. The In vitro cytotoxicity assay indicates higher than 70% cell viability for all nanostructures at 100, 300, and 500 ppm after 24 and 72 h. Additionally, cancerous cell (EJ138 human bladder carcinoma) ablation is observed using functionalized GO/SPION under applied magnetic field. More than 50% cancerous cell death has been achieved for GO/SPION@PEG at 300 ppm concentration. Furthermore, Surrogate virus neutralization test is applied to investigate neutralizing property of the synthesized nanostructures through analysis of SARS-CoV-2 receptor-binding domain and human angiotensin-converting enzyme 2 binding. The highest level of SARS-CoV-2 virus inhibition is related to GO/SPION@CS (86%) due to the synergistic exploitation of GO and chitosan. Thus, GO/SPION and GO/SPION@PEG with higher SAR and ILP values could be beneficial for cancer treatment, while GO/SPION@CS with higher virus suppression has potential to use against coronaviruses. Thus, the developed nanocomposites have a potential in the efficient treatment of cancer and coronavirus.

Safety Analysis of Medical Implants in the Human Head Exposed to a Wireless Power Transfer System

The interactions of medical implants in the human body with electromagnetic fields from newly introduced high-field technologies such as near-field wireless power transfer (WPT) are of great concern. In this study, the effects of implants on the specific absorption rate (SAR) in a head model were computationally evaluated in the immediate vicinity of a WPT system operating at 6.78 MHz with a transferred power of 50 W. The SAR in the head model located 30 mm above the WPT system was evaluated with a skull plate, bone plates (different shapes), miniplate, fixtures, and a deep brain stimulator. The results indicated that even small implants had notable effects on the SAR distribution and corresponding local peak and mass-averaged SAR values. Apart from the size and shape of the implant, the crucial factor influencing the SAR was the implant’s position with respect to the WPT system. Therefore, various position configurations were simulated for the WPT system to determine the worst case scenario for each specific implant. Although the local peak SAR value was increased by a factor of 600 in the worst-case scenario (for the skull plate), the SAR <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{\text{1}g}$</tex-math></inline-formula> and SAR <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{\text{10}g}$</tex-math></inline-formula> were only increased by factors of seven and four, respectively. Compliance with international safety limits was studied, followed by computing the maximum allowable transmit power (MATP). It was found that, without the implant, the MATP satisfying SAR <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{\text{1}g}$</tex-math></inline-formula> was 43 W for the designed WPT system, and was reduced to 6.9 W in the presence of the skull plate.

Compact triple-band implantable antenna for multitasking medical devices

Abstract This paper presents a compact implantable antenna’s design, fabrication, and measurement for biotelemetry applications. The proposed design with the size of 255 mm3 provides a triple-band operation that covers all the Medical Implant Communication Service (MICS: 402 MHz), Medical Device Radiocommunications Service (MedRadio: 405 MHz), and Industrial, Scientific, and Medical (ISM: 433, 915 and 2450 MHz) bands simultaneously. The compact structure with triple- band performance is essentially achieved by using a spiral-like radiator loaded with meandered and internal gear-shaped elements excited by a vertical coaxial probe feed. Also, the slots-loaded partial ground plane is utilized to improve impedance matching at the desired frequency bands. The design and analysis of the antenna were carried out using the Ansoft HFSS software in a homogenous skin model and the CST Microwave Studio in a realistic human model. The proposed antenna was fabricated to validate the simulated results, and characteristics of its return loss and radiation patterns were measured in minced pork meat. Moreover, realized gains and specific absorption rate (SAR) values of the antenna were numerically computed using the simulators. Based on the simulated and measured results, the proposed antenna performance was found to be comparable to the limited number of multiband implantable antenna designs reported in the recent literature.

Functionalized iron oxide nanoparticles: synthesis through ultrasonic-assisted co-precipitation and performance as hyperthermic agents for biomedical applications

Dual-functional iron oxide nanoparticles (IONPs), displaying self-heating and antibacterial effects are highly desired for biomedical application. This study involved the synthesis of functionalized IONPs coated with 3-aminopropyltriethoxysilane and polyethylene glycol via ultrasonic-assisted co-precipitation technique. The synthesized IONPs were then characterized by using Fourier-transform infrared spectroscopy, X-ray diffraction, dynamic light scattering, scanning electron microscopy, zeta potential, vibrating sample magnetometer and thermogravimetric analysis techniques. In addition, the effect of the synthesized IONPs on bacterial growth (S. aureus and E. coli) was studied. The influence of magnetic field power, as well as the viscous carriers on the heating efficiency of the synthesized IONPs was investigated. The specific absorption rate values increased as the power increased and decreased with the increase in the carrier viscosity. These characteristics render the synthesized iron oxide nanoparticles synthesized in the present study suitable for biomedical application as hyperthermic agents.

Numerical analogy of bioheat transfer and microwave cancer therapy for liver tissue

AbstractA numerical study of microwave cancer therapy for cylindrical‐shaped liver tissue with an elliptical‐shaped liver tumor has been carried out by this study. The time‐dependent electromagnetic wave and the bio‐heat transfer equations have been used as the governing equations and solved with appropriate boundary conditions using Galerkin's weighted residual scheme built‐in finite element method‐based COMSOL Multiphysics software. The coaxial applicator as well as the effects of different microwave input power levels (from 5 to 25 W), frequencies (from 0.7 to 5 GHz), and treatment time (from 0 to 1000 s) on hepatocellular carcinoma have been examined by this simulation and displayed graphically in terms of the microwave power dissipation, isothermal lines inside liver tissue, time‐dependent profiles of temperature at different locations inside the tumor, specific absorption rate (SAR), and surface average transient temperature distribution of tumor tissue. The results demonstrate that microwave input antenna power and frequency have significant impacts on the temperature distribution and SAR values of liver tissue. When the microwave input power, as well as frequency, is increased, SAR and tissue temperature values also increase but the high temperature is harmful to healthy tissue. It is observed from the performed analysis that the mean temperature of the tumor cell is about 56.86°C at a time of 180 s using 10 W microwave input power and 2.45 GHz frequency.

Wearable Blood Pressure Sensing Based on Transmission Coefficient Scattering for Microstrip Patch Antennas.

Painless, cuffless and continuous blood pressure monitoring sensors provide a more dynamic measure of blood pressure for critical diagnosis or continuous monitoring of hypertensive patients compared to current cuff-based options. To this end, a novel flexible, wearable and miniaturized microstrip patch antenna topology is proposed to measure dynamic blood pressure (BP). The methodology was implemented on a simulated five-layer human tissue arm model created and designed in High-Frequency Simulation Software “HFSS”. The electrical properties of the five-layer human tissue were set at the frequency range (2–3) GHz to comply with clinical/engineering standards. The fabricated patch incorporated on a 0.4 mm epoxy substrate achieved consistency between the simulated and measured reflection coefficient results at flat and bent conditions over the frequency range of 2.3–2.6 GHz. Simulations for a 10 g average specific absorption rate (SAR) based on IEEE-Standard for a human arm at different input powers were also carried out. The safest input power was 50 mW with an acceptable SAR value of 3.89 W/Kg < 4W/Kg. This study also explored a novel method to obtain the pulse transit time (PTT) as an option to measure BP. Pulse transmit time is based on obtaining the time difference between the transmission coefficient scattering waveforms measured between the two pairs of metallic sensors underlying the assumption that brachial arterial geometries are dynamic. Consequently, the proposed model is validated by comparing it to the standard nonlinear Moens and Korteweg model over different artery thickness-radius ratios, showing excellent correlation between 0.76 ± 0.03 and 0.81 ± 0.03 with the systolic and diastolic BP results. The absolute risk of arterial blood pressure increased with the increase in brachial artery thickness-radius ratio. The results of both methods successfully demonstrate how the radius estimates, PTT and pulse wave velocity (PWV), along with electromagnetic (EM) antenna transmission propagation characteristics, can be used to estimate continuous BP non-invasively.

Investigation on the physico-chemical properties, hyperthermia and cytotoxicity study of magnesium doped manganese ferrite nanoparticles

The superparamagnetic nanoparticles (SPNPs) should be chemically stable and biocompatibility for magnetic hyperthermia (MHT) application. Cubic spinel structured MgFe2O4 and MnFe2O4 NPs were well studied for catalytic and sensor applications by employing their semiconducting property. Here we explore the biocompatible and soft magnetic properties of these ferrites for MHT application. Narrow size distributed Mn1-xMgxFe2O4 (x = 0.1, 0.3, 0.4 & 0.5) NPs with average crystallite size of 12 nm were synthesized by solvothermal reflux method. All compounds were crystallined in cubic spinel structure and were confirmed by X-ray diffraction, electron diffraction, high-resolution lattice fringe profiles, and infrared spectrum. Energy dispersive, photoelectron spectroscopy, and elemental mapping studies revealed that the compounds have chemical stoichiometry close to the target composition. Thermal analysis shows that the spinel compounds are thermally stable even above 800 °C. All compounds show superparamagnetic (SP) nature at room temperature and show a decrease of saturation magnetization (Ms) after substituting x = 0.3 concentration with increases of substituent Mg2+ concentration in the MnFe2O4. The x = 0.1, 0.3, 0.4 & 0.5 samples show MHT specific absorption rate (SAR) of 63.67, 108.37, 97.58, & 45.08 Wg-1 at 1 mg/mL, respectively. The decrease in SAR values is attributed to reduced magnetic moments and spin relaxation. Furthermore, monosize characteristics of Mn1-xMgxFe2O4 (x = 0.1, 0.3, 0.4, & 0.5) NPs at 0–950 g/mL concentrations were reported to be non-toxic in human breast cancer (MDA-MB-23) and human prostate cancer (PC-3) cells.

Design and modeling of a multiband electrically coupled loop antenna for biomedical applications

A triple-band Electrically Coupled Loop Antenna (ECLA) is designed to operate in the three standard bands for biomedical implantation purposes: Medical Implant Communications Services (MICS) (402–405 MHz), Wireless Medical Telecommunication Services (WMTS) (1395–1405 MHz) and Industrial, Scientific, and Medical (ISM) (2400–2480 MHz). An equivalent circuit is derived for the multiband ECLA based on simple equations relate the dimensions with the circuit parameters to get a good understanding of antenna operation as well as saving time in simulations. The proposed antenna size is 15 × 13.8 × 13 mm3 and simulated in a muscle phantom with size 100 × 100 × 100 mm3. The calculated peak realized gain values are − 18, − 30 and − 33.3 dBi and the peak 10 g averaged Specific Absorption Rate (SAR) values are 11.59, 43.07 and 49.75 W/Kg for the three bands, respectively. A detuning study is carried out to ensure that the proposed antenna is robust against electrical properties variation thus it can be implanted in different tissues of different people in various health circumstances. Two antenna prototypes have been fabricated and tested in a solution that mimics human tissue.

Specific absorption rate assessment of fifth generation mobile phones with specific anthropomorphic mannequin model and high‐resolution anatomical head model

With the spread and application of the fifth generation (5G) of mobile communication technology, the number of 5G mobile phone users increase rapidly. The traditional safety standard of electromagnetic radiation of mobile phones was set two decades ago, in which a homogeneous specific anthropomorphic mannequin (SAM) head model with standardized size and shape is utilized for specific absorption rate (SAR) evaluation. The SAM model has been proved conservative for SAR evaluation of 2G, 3G and 4G mobile phone antennas. However, it needs to be validated whether it is still suitable for SAR evaluation of 5G mobile phone antennas. A high-resolution anatomical head model with tissues including muscle, skull, cerebrospinal fluid and brain is developed in this paper. The SAR values of three different generation mobile phone antennas are simulated by utilizing both the SAM model and the high-resolution anatomical head model to assess their applicability. Numerical simulations show that the anatomical model may produce a higher SAR value than the SAM model for a 5G mobile phone antenna. So new head model may need to be developed for the SAR evaluation of 5G mobile phone antennas.

All-Textile On-Body Antenna for Military Applications

An all-textile cavity-backed substrate integrated waveguide (SIW) antenna is proposed for military applications. The antenna matches standard military badge size. The aircraft-shape badge antenna that operates in X-band is designed for air force. SIW cavity and meandered slots that form the body and wing of the figure provide resonance at 8 GHz with 26&#x0025; bandwidth. Symmetrical boresight patterns with very low sidelobes are observed. The measured gain and efficiency of the structure are 5.2 dBi and 79.2&#x0025; at 8 GHz, respectively. This efficiency value is the highest among other SIW cavity textile-antennas. The antenna is investigated on conformal surfaces, as well. Bending of the antenna to follow body movements does not deteriorate performance of the textile antenna sensor. The peak specific absorption rate value over 10 g of tissue was 0.53 and 0.69 W&#x002F;kg for 30 dBm input power for female and male breasts, which makes it suitable as an on-body antenna. The badge antenna is fabricated with standard textile fabrication techniques and its simulation performance is confirmed successfully by measurements. Usage of standard off-the-shelf parts for the assembly and fabrication with standard textile fabrication techniques enables simple and cost-effective mass production of the proposed badge antenna.

Design of a wideband patch antenna and performance enhancement using an AMC reflector surface for on-body communication at 2.45 GHz

ABSTRACT Wireless biotelemetry enables the formation of communication link from living body to an external monitoring device. Isolation of near field electromagnetic (EM) waves from body tissue, and wide bandwidth to avoid frequency detuning in different biological environments are the important parameters of on-body antennas. In this paper, a conformal defected ground patch antenna with artificial magnetic conductor (AMC) is introduced for on-body communication. Initially, a quarter wave wide band antenna with a shorting pin is designed to operate at 2.45 GHz. It resonates effectively on body tissue but most of the near field EM radiations are absorbed by tissue. Poor radiation efficiency of 10% and high specific absorption rate (SAR) value of 7.73 W/Kg were obtained. Thus, to reduce the effect of tissue loading on antenna performance an AMC-based structure is added. Better impedance matching, high efficiency (65%) and directivity (7.3 dBi) is achieved with AMC structure. Furthermore, unidirectional radiation pattern with SAR value of 1.43W/Kg is attained. Wide bandwidth of 600 MHz on phantom enables the antenna to withstand frequency detuning effect due to body postures and movements. Antenna robustness is analysed by bending the structure at different radii along X-axis and Y-axis.

Design and performance analysis of wearable antenna for ISM band applications

ABSTRACT The paper proposes a wearable multiband antenna applicable for ISM (Industrial, Scientific and Medical) band, bluetooth, WiMAX, upper WLAN, fifth-generation (5G) smartphone applications, INSAT and radio altimeter, X-band, point-to-point hi-speed wireless, satellite TV, and C-band applications. This antenna is designed to function at resonance frequencies of 2.45 GHz, 4.6 GHz, 6.6 GHz and 8.2 GHz. The proposed textile antenna design dimensions are 50x80x0.56mm3.The antenna presented 47% impedance bandwidth covering the ISM band. The simulated value of the gain provided by the proposed wearable textile antenna is 5.59 dBi, 3.67 dBi, 3.99 dBi, 4.42 dBi at 2.45 GHz, 4.6 GHz, 6.6 GHz and 8.2 GHz resonant frequencies respectively.Simulations are therefore carried out using the human tissue model to show the specific absorption rate (SAR) value of the proposed antenna at different resonant frequencies. The antenna is fabricated and the simulated reflection coefficient validation is done with the measured results. The Antenna in off space provides 45% (2.1-3.32 GHz) impedance bandwidth. The antenna measured on the back of the human body provides percentage impedance bandwidth of 145% covering 1.4 to 8.8 GHz frequency band applicable for ISM band and other wireless applications.

Substrate integrated waveguide‐based simultaneous transmit and receive antenna for full‐duplex wearable devices

In this paper, a low-size and compact substrate integrated waveguide (SIW)-based simultaneous transmit and receive antenna is developed for full-duplex wearable telemetry applications. The antenna operates at 4.9 GHz (Wireless Local Area Network [WLAN]) and 5.8 GHz (Industrial, Scientific and Medical [ISM]) bands with acceptable gains. Keeping a proper gap between the two ports achieves an isolation of better than 29.8 dB. This antenna is kept compact (0.20 λg2, where λg is the wavelength at 4.9 GHz) by additional arc-shaped slot in each radiator, which adds additional capacitance. The suggested antenna is simulated inside a 52 × 63 × 17 mm3 dummy wearable telemetry device and is worn on the subject's chest. Thanks to SIW technology, it has unidirectional radiation patterns, allowing a minimum beam towards the human body, and thus, offers lower specific absorption rate (SAR) at both frequency bands. The unique advantage is its capacity to receive and transmit the telemetry signals simultaneously. Its low profile, flexibility in the resonant bands, simultaneous transmission and reception, and lower SAR values make this antenna suitable for full-duplex wearable telemetry devices.

Ultra-Wideband Circular Microstrip Antenna with Hybrid EBG for reduced SAR

This article presents a basic ultra-wideband circular microstrip antenna (UWB-CMSA) with partial ground resonating from 2.38 GHz to 12 GHz for handheld devices. The designed antenna covers bands for Bluetooth (2.4 GHz), LTE (2.5/2.69 GHz), WLAN (2.4/3.5/5 GHz), and WiMAX (2.5/3.5/5.5) GHz applications. Specific Absorption Rate (SAR) values of certain bands exceed a limit for UWB-CMSA. The uniplanar spiral unit cell is designed and exhibits phase reversal for 2.4 GHz, 3.5 GHz, and 5.5 GHz. EBG unit cells are placed near the feed for surface wave minimization so as to achieve a reduction in SAR. Furthermore, the EBG structure is placed on the ground plane to analyze the impact, also designs are fabricated and results are compared. Mushroom type M-shaped unit cell is designed which offers phase reversal at 2.3 GHz which is placed near feed in a similar fashion to the earlier spiral one to suppress surface waves also the structure is investigated by arranging it on the ground plane. It is evident that SAR is reduced for all the cases being inspected but for certain bands it exceeds the limit of 1.6 W/kg. A combination of two different unit cells to form a hybrid EBG structure is proposed and evaluated by placing it near the feed. SAR is curtailed by 87.05% at 5.5 GHz.

A novel and effective technique to reduce electromagnetic radiation absorption on biotic components at 2.45 GHz

ABSTRACT A strong evidence of the effects of radiation absorption on the living community together with a better solution to reduce the radiation intensity without compromising the usage of wireless communication systems is presented. This study analyses the radiation effects on living things and validates the proposed techniques for specific absorption rate (SAR) value reduction at 2.45 GHz. To reduce these radiation impacts on the living community, proper shielding from the radiation and effectively reorienting antenna radiation patterns are the solutions suggested. An analogous antenna configuration in wireless communication systems – a coplanar waveguide fed loop antenna is considered and an open loop resonator (OLR) optimized in ANSYS HFSS at 2.45 GHz is incorporated on the back side of the proposed antenna for achieving SAR value reduction. Theoretical and experimental validation is carried out by measuring the variation in absorption power on each vegetable sample using vector network analyzer E5080A. The existence of OLR on the back side of the antenna reduces the absorption power upto 2 dB. From experimental validation, the proposed technique provides 88% to 98% reduction in SAR value when tested in each sample. Along with this OLR exhibits the capability to enhance the shielding characteristics to the controlled environment of experimental setup for analyzing the stages of seed germination, which helps in reducing the reported radiation effects and growth retardation. The proposed method of EMR reduction with miniaturized planar resonator can be effectively used in the communication systems operating at 2.45 GHz for creating a reduced radiation environment.

CTAB assisted synthesis of MnFe2O4@ SiO2 nanoparticles for magnetic hyperthermia and MRI application

Magnetic fluid hyperthermia (MFH) has been proven as a promising cancer therapeutic approach in conjunction with chemotherapy or physiotherapy in patients. The research to find innovative materials with a higher specific absorption rate (SAR) to reduce the dose of magnetic nanoparticles in tumor treatment through MFH while being also adequate for Magnetic Resonance Imaging (MRI) is important. Herein, MnFe2O4 NPs were synthesized with different sizes, using NaOH or NH4OH as a reducing agent, via a green-assisted hydrothermal route. A tetraethyl orthosilicate with the assist of cetrimonium bromide was used to fabricate SiO2 @MnFe2O4 NPs. Based on the Mössbauer and XRD results an undesired amount of α-Fe2O3 was found in the samples synthesized with NH4OH. Concentration-dependent cellular toxicity values were evaluated by invitro 3-(4,5 dimethylthiazol-2-yl)−2,5-diphenyltetrazolium bromide (MTT) assay on A549 cells, where bare and silica coated nanoparticles exhibited non-toxicity below 691 µg/mL and 566 µg/mL, respectively. The ability of bare MnFe2O4 as the MRI contrast agent was higher compared to the silica-coated sample. The heating efficiency of the ferrofluids was recorded at 128 kHz and 10 kA/m and the highest SAR value was 39 W/g for the pristine MnFe2O4 NPs, making them promising potential materials in MRI and cancer treatment.

Awareness of Mobile Phone Radiation and Its Potential Health Hazards Among Students and Working-class Population During the COVID-19 Pandemic

COVID-19 pandemic has caused an increased dependence on mobile phones by students and working professionals. Mobile phones are indispensable gadgets with a wide range of applications. However, there are potential risks associated with its usage in terms of radiofrequency radiation. The objective of this study was to evaluate the knowledge of radiation and its biological adverse effects caused due to the usage of mobile phones among students and working professionals. An online awareness survey was conducted during the COVID-19 pandemic among 351 participants using Google forms. The questionnaire was disseminated to the WhatsApp groups of students and working professionals and the data was statistically analysed. Among the 351 subjects, 72% of the respondents used their mobile phones for more than 4 hours per day. However, less than 20% were fully aware of mobile phone radiation being listed in the possible carcinogen list by the World Health Organization (WHO). In addition, only half of the respondents considered the Specific Absorption Rate (SAR) value and information on radiation emission while purchasing a new phone. To conclude, the need for awareness of potential hazards associated with the mobile phone radiation seems crucial, especially during this time when everyone in the world and especially school and college students are highly dependent on mobile phones.

Design and Evaluation of a Button Sensor Antenna for On-Body Monitoring Activity in Healthcare Applications.

A button sensor antenna for on-body monitoring in wireless body area network (WBAN) systems is presented. Due to the close coupling between the sensor antenna and the human body, it is highly challenging to design sensor antenna devices. In this paper, a mechanically robust system is proposed that integrates a dual-band button antenna with a wireless sensor module designed on a printed circuit board (PCB). The system features a small footprint and has good radiation characteristics and efficiency. This was fabricated, and the measured and simulated results are in good agreement. The design offers a wide range of omnidirectional radiation patterns in free space, with a reflection coefficient (S11) of dB, a maximum gain of dBi, and radiation efficiency of % in the lower and upper bands, respectively. S11 reaches dB and ) dB, respectively, with a gain of dBi and dBi, and radiation efficiency of and , when located on the body for the lower and upper bands, respectively. The performance is minimally affected by bending, movement, and fabrication tolerances. The specific absorption rate (SAR) values are below the regulatory limitations for the spatial average over 1 g (1.6 W/Kg) and 10 g of tissues (2.0 W/Kg). For both indoor and outdoor conditions, experimental results of the range tests confirm the coverage of up to 40 m.

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

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