Vicinity Of Human Body Research Articles

Wearable near‐field communication bracelet based on highly conductive graphene‐assembled films

Benefiting from the high conductivity and superb flexibility, graphene-based materials are promising to replace metal for near-field communication (NFC) applications. Herein, we report a flexible NFC tag antenna based on high-conductivity graphene-assembled films (HCGAFs) and investigate how the performance of the antenna is affected by antenna design and human body effect. The fabricated prototype via a one-step laser-direct mold engraving method shows a 10 dB bandwidth of 2.5 MHz centering at 13.70 MHz with a quality factor (Q) of 9.19. The maximum read range of the HCGAF NFC tag is measured to be around 7.5 cm, comparable to the commercially available metal NFC tags. Moreover, the flexible nature of HCGAFs guarantees excellent mechanical stability and deformation insensitivity, especially when compared to commercial metal-based counterparts. We further demonstrate the practical applications of the HCGAF tag as key card and electronic business card in the vicinity of human body.

Impacts of exhalation flow on the microenvironment around the human body under different room temperatures

Exhalation flow and room temperature can have a considerable effect on the microenvironment in the vicinity of human body. In this study, impacts of exhalation flow and room temperature on the microenvironment around a human body were investigated using a numerical simulation. For this purpose, a computational fluid dynamic program was applied to study thermal plume around a sitting human body at different room temperatures of a calm indoor room by considering the exhalation flow. The simulation was supported by some experimental measurements. Six different room temperatures (18 to 28 °C) with two nose exhalation modes (exhalation and non-exhalation) were investigated. Overhead and breathing zone velocities and temperatures were simulated in different scenarios. This study finds out that the exhalation through the nose has a significant impact on both quantitative and qualitative features of the human microenvironment in different room temperatures. At a given temperature, the exhalation through the nose can change the location and size of maximum velocity at the top of the head. In the breathing zone, the effect of exhalation through the nose on velocity and temperature distribution was pronounced for the point close to mouth. Also, the exhalation through the nose strongly influences the thermal boundary layer on the breathing zone while it only minimally influences the convective boundary layer on the breathing zone. Overall results demonstrate that it is important to take the exhalation flow into consideration in all areas, especially at a quiescent flow condition with low temperature.

Wearable Antenna Measurements in Vicinity of Human Body

This paper presents measurements techniques of wearable antennas and RF medical systems in vicinity of human body. The antennas radiation characteristics on human body have been measured by using a phantom. The phantom electrical characteristics represent the human body electrical characteristics. The phantom has a cylindrical shape with a 40 cm diameter and a length of 1.5 m. The phantom electrical characteristics are similar to the human body electrical characteristics. The antenna under test was placed on the phantom during the measurements of the antennas radiation characteristics. The phantom was employed to compare the electrical performance of several new wearable antennas. The phantom was also employed to measure the electrical performance of several antenna belts in vicinity of human body. The results of antenna with thinner belt are better than the results of the same antenna array with thicker belt.

Small Antennas Used in the Vicinity of Human Body

Recently, wearable wireless devices or terminals have become hot a topic not only in research but also in business. Implantable wireless devices can temporarily be utilized to monitor a patient’s condition in an emergency situation or to identify people in highly secured places. Unlike conventional wireless devices, wearable or implantable devices are used on or in the human body. In this sense, body-centric wireless communications (BCWCs) have become a very active area of research. Radiofrequency or microwave medical devices used for cancer treatment systems and surgical operation have completely different functions, but they are used on or in the human body. In terms of research techniques, such medical devices have a lot of similarities to BCWCs. The antennas to be used in the vicinity of the human body should be safe, small and robust. Also, their interaction with the human body should be well considered. This review paper describes some of the wearable antennas as well as implantable antennas that have been studied in our laboratory. key words: wearable antenna, implantable antenna, body-centric wireless communications, RFID, hyperthermia, medical device, human body, phantom

Influence of a breathing process on the perception of the thermal environment using personalised ventilation

This paper presents the findings of a study examining the influence of the breathing process on the perception of the thermal environment during the use of personalised ventilation (PV). The measurements were made on a sitting thermal manikin with various options of air terminal device, ambient temperature and PV air supply. The thermal environment was assessed by means of the equivalent temperatures measured for each segment of the thermal manikin. The values of teq were calculated for the variants of the breathing function being switched on or off. Based on the measurement results, the values of equivalent temperature were determined to be lower for a breathing variant than for a non-breathing variant, irrespective of whether the PV system was used to heat or to cool. Therefore, the results confirmed that breathing air jets have the potential to influence the users' thermal sensation. This information is particularly important for the design of the ventilation and air conditioning systems that affect the parameters of the environment in the vicinity of human body.

Near-field radiofrequency electromagnetic exposure assessment

Personal wireless telecommunication devices, such as radiofrequency (RF) electromagnetic field (EMF) sources operated in vicinity of human body, have possible adverse health effects. Therefore, the correct EMF assessment is necessary in their near field. According to international near-field measurement criteria, the specific absorption rate (SAR) is used for absorbed energy distribution assessment in tissue simulating liquid phantoms. The aim of this investigation is to validate the relationship between the H-field of incident EMF and absorbed energy in phantoms. Three typical wireless telecommunication system frequencies are considered (900, 1800 and 2450 MHz). The EMF source at each frequency is an appropriate half-wave dipole antenna and the absorbing medium is a flat phantom filled with the suitable tissue simulating liquid. Two methods for SAR estimation have been used: standard procedure based on E-field measured in tissue simulating medium and a proposed evaluation by measuring the incident H-field. Compared SAR estimations were performed for various distances between sources and phantom. Also, these research data were compared with simulation results, obtained by using finite-difference time-domain method. The acquired data help to determine the source near-field space characterized by the smallest deviation between SAR estimation methods. So, this region near the RF source is suitable for correct RF energy absorption assessment using the magnetic component of the RF fields.

Performance of Electro-Textile Wearable Circular Patch Antennas in the Vicinity of Human Body at 2.45 GHz

Impedance and radiation characteristics of 2.45 GHz wearable antennas in close proximity to human body are discussed in this paper. Three circular microstrip antennas namely Flectron antenna, Zelt antenna and Shieldit antenna are considered in this research work. Each of these three antennas is assumed to be placed in the vicinity of human torso with an air gap of 1 mm between torso and antenna. In this study, the human torso has been modeled as a lossy medium of fluid with permittivity and conductivity close to human torso at a frequency of 2.45 GHz. The results obtained indicate that the wearable antenna can provide required impedance and radiation characteristics even when it is placed in the vicinity of human body.

SAR DISTRIBUTION IN A BIO-MEDIUM IN CLOSE PROXIMITY WITH RECTANGULAR DIELECTRIC RESONATOR ANTENNA

In this paper, the simulation and experimental studies of SAR distribution in a bio-medium situated very close to a rectangular dielectric resonator antenna (RDRA) in C-band of microwave frequencies are reported. The simulation study has been carried out using CST Microwave Studio simulation software. The experimental distribution has been obtained using two 50› L-shaped and straight probes and Agilent make 3Hz{50GHz spectrum analyzer. The experimental results for SAR distribution are compared with simulated results. The use of wireless portable devices is growing at fast rate throughout the world. These devices are often used in the vicinity of human body. The continuous growth of wireless portable devices has forced the worldwide researchers to study the interaction between the electromagnetic waves emanating from the device antenna and the human body. The human body, being lossy, absorbs certain amount of electromagnetic radiation generated from portable wireless device situated in its vicinity. This necessitates the evaluation of the performance of antenna in terms of input VSWR, return loss and bandwidth of antenna in presence of bio-medium on one hand and the estimation of the rate of electromagnetic energy absorption, known as speciflc absorption rate (SAR) in the body tissues on the other (1,2). The electric fleld induced and hence SAR within the human body

Inhalation Exposure and Accessibility of Source in the Vicinity of Human Body

Inhalation Exposure and Accessibility of Source in the Vicinity of Human Body