In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and ...energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction materials. Several properties of the materials influence the behaviour of the antenna. For instance, the bandwidth and the efficiency of a planar microstrip antenna are mainly determined by the permittivity and the thickness of the substrate. The use of textiles in wearable antennas requires the characterization of their properties. Specific electrical conductive textiles are available on the market and have been successfully used. Ordinary textile fabrics have been used as substrates. However, little information can be found on the electromagnetic properties of regular textiles. Therefore this paper is mainly focused on the analysis of the dielectric properties of normal fabrics. In general, textiles present a very low dielectric constant that reduces the surface wave losses and increases the impedance bandwidth of the antenna. However, textile materials are constantly exchanging water molecules with the surroundings, which affects their electromagnetic properties. In addition, textile fabrics are porous, anisotropic and compressible materials whose thickness and density might change with low pressures. Therefore it is important to know how these characteristics influence the behaviour of the antenna in order to minimize unwanted effects. This paper presents a survey of the key points for the design and development of textile antennas, from the choice of the textile materials to the framing of the antenna. An analysis of the textile materials that have been used is also presented.
The Internet of Things (IoT) scenario is strongly related with the advance of the development of wireless sensor networks (WSN) and radio frequency identification (RFID) systems. Additionally, in the ...WSN context, for a continuous feed, the integration of textile antennas for energy harvesting into smart clothing is a particularly interesting solution when the replacement of batteries is not easy to practice, such as in wearable devices. This paper presents the E-Caption: Smart and Sustainable Coat. It has an embedded dual-band textile antenna for electromagnetic energy harvesting, operating at global system for mobile communication (GSM) 900 and digital cellular system (DCS) 1800 bands. This printed antenna is fully integrated, as its dielectric is the textile material composing the coat itself. The E-Caption illustrates the innovative concept of textile antennas that can be manipulated as simple emblems. Seven prototypes of these "emblem" antennas, manufactured by lamination and embroidering techniques are also presented. It is shown that the orientation of the conductive fabric does not influence the performance of the antenna. It is also shown that the direction and number of the stitches in the embroidery may influence the performance of the antenna. Moreover, the comparison of results obtained before and after the integration of the antenna into cloth shows the integration does not affect the behavior of the antenna.
A bio-radar system is presented for vital signs acquisition, using textile antennas manufactured with a continuous substrate that integrates the ground plane. Textile antennas were selected to be ...used in the RF (Radio Frequency) front-end, rather than those made of conventional materials, to further integrate the system in a car seat cover and thus streamline the industrial manufacturing process. The development of the novel substrate material is described in detail, as well as its characterization process. Then, the antenna design considerations are presented. The experiments to validate the textile antennas operation by acquiring the respiratory signal of six subjects with different body structures while seated in a car seat are presented. In conclusion, it was possible to prove that bio-radar systems can operate with textile-based antennas, providing accurate results of the extraction of vital signs.
This paper presents a study of the electrical and mechanical behavior of several continuous carbon fibers epoxy composites for both strengthening and monitoring of structures. In these composites, ...the arrangement of fibers was deliberately diversified to test and understand the ability of the composites for self-sensing low strains. Composites with different arrangements of fibers and textile weaves, mainly unidirectional continuous carbon reinforced composites, were tested at the dynamometer. A two-probe method was considered to measure the relative electrical resistance of these composites during loading. The measured relative electrical resistance includes volume and contact electrical resistances. For all tested specimens, it increases with an increase in tensile strain, at low strain values. This is explained by the improved alignment of fibers and resulting reduction of the number of possible contacts between fibers during loading, increasing as a consequence the contact electrical resistance of the composite. Laboratory tests on strengthening of structural elements were also performed, making hand-made composites by the "wet process", which is commonly used in civil engineering for the strengthening of all types of structures in-situ. Results show that the woven epoxy composite, used for strengthening of concrete elements is also able to sense low deformations, below 1%. Moreover, results clearly show that this textile sensor also improves the mechanical work of the strengthened structural elements, increasing their bearing capacity. Finally, the set of obtained results supports the concept of a textile fabric capable of both structural upgrade and self-monitoring of structures, especially large structures of difficult access and needing constant, sometimes very expensive, health monitoring.
IntroductionIntestinal microbiota is arising as a new element in the physiopathology of cardiovascular diseases. A healthy microbiota includes a balanced representation of bacteria with health ...promotion functions (symbiotes). The aim of this study is to analyse the relationship between intestinal microbiota composition and arterial stiffness.Methods and analysisAn observational case—control study will be developed. Cases will be defined by the presence of at least one of the following: carotid-femoral pulse wave velocity (cf-PWV), Cardio-Ankle Vascular Index (CAVI), brachial ankle pulse wave velocity (ba or ba-PWV) above the 90th percentile, for age and sex, of the reference population. Controls will be selected from the same population as cases. The study will be developed in Primary Healthcare Centres. We will select 500 subjects (250 cases and 250 controls), between 45 and 74 years of age. Cases will be selected from a database that combines data from EVA study (Spain) and Guimarães/Vizela study (Portugal). Measurements: cf-PWV will be measured using the SphygmoCor system, CAVI, ba-PWV and Ankle-Brachial Index will be determined using VaSera device. Gut microbiome composition in faecal samples will be determined by 16S ribosomal RNA sequencing. Lifestyle will be assessed by food frequency questionnaire, adherence to the Mediterranean diet and IPAQ (International Physical Activity Questionnaire). Body composition will be evaluated by bioimpedance.Ethics and disseminationThe study has been approved by ‘Committee of ethics of research with medicines of the health area of Salamanca’ on 14 December 2018 (cod. 2018-11-136) and the ’Ethics committee for health of Guimaraes’ (Portugal) on 15 October 2019 (ref: 67/2019). All study participants will sign an informed consent form agreeing to participate in the study, in compliance with the Declaration of Helsinki and the WHO standards for observational studies. The results of this study will allow a better description of gut microbiota in patients with arterial stiffness.Trial registration detailsClinicalTrials.gov, identifier NCT03900338
Externally bonded composites reinforced with high-strength fibers are increasingly popular in construction, especially in structures’ strengthening, where the best possible mechanical properties are ...required. At the same time the ability to autodetect threats is one of the most desirable features of contemporary structures. The authors of the paper have developed an intelligent fabric, wherein the carbon fibers play the role of not only tensile reinforcement but also strain sensor. The idea is based on the construction of the strain gauge, where the thread of carbon fibers arranged in zig-zag pattern works as electrical conductor and is insulated by parallel thread of glass or acrylic fibers. Preliminary laboratory tests were designed to create effective measurement techniques and assess the effectiveness of the strengthening of selected building structures, as reinforced concrete and timber beams. Presented in the paper, selected results of these studies are very promising, although there were some noted problems to be considered in next steps. The main problem here is the control of the cross section of the fibers tow, affecting the total resistance of the fabric. One of the main deficiencies of the proposed solution is also sensitivity to moisture.
Objective
To analyze the reliability and validity of Pulse Wave Analysis determined with the new wrist-worn tonometry.
Methods
Cross sectional study including 254 subjects. Aged 51.9 ± 13.4, being ...women 53%. Main measurements: Peripheral AIx (PAIx) and Central AIx (CAIx) by wrist-worn tonometry and Sphygmocor. Carotid femoral (cf) pulse wave velocity (PWV) by Sphygmocor, Cardio Anckle Vascular index (CAVI), anckle brachial index (ABI) and brachial anckle (ba) PWV by Vasera device. Carotid intima media thickness (IMT) by ultrasonography.
Results
Intra-class correlation coefficient (ICC) intraobserver for the PAIx was 0.886 (95% CI 0.803 to 0.934) and for the CAIx 0.943 (0.901 to 0.968) with a Bland Almant agreement limit of −0.75 (−23.8 to 21.8) and 0.08 (−15.7 to 15.9) respectively. ICC interobserver for PAIx was 0.952 (95% CI 0.915 to 0.972) and CAIx 0.893 (0.811 to 0.939) with an agreement limit of −0.45 (−13.7 to 12.8) and 0.43 (−17.7 to 1835) respectively. We found, compared with Sphygmocor, an ICC of 0.849 (0.798 to 0.887) for PAIx, and 0.783 (0.711 to 0.838) for CAIx. The agreement limit for PAIx was −1.03 (−22.73 to 20.67) and CAIx 2.14 (−20.50 to 24.79). We found positive correlation with PAIx, CAIx and CAIx HR75 by Aurora with age, CAVI, ABI, baPWV, cfPWV, IMT and cardiovascular risk and negative with glomerular filtration rate.
Conclusions
The wrist-worn tonometry shows an adequate reliability intra and interobserver, and interdevice when compared to Sphygmocor, and an adequate validity when compared with other measures that evaluate arterial stiffness, target organ damage and cardiovascular risk.
This paper presents results of mechanical tests
on a prototype of an innovative structural strengthening
in form of self-monitoring fabric. Smart textile employs
carbon fibers conductivity for ...measuring strains while
monitoring changes of electric resistance under increasing
load. A general solution was tested in a series of calibrating
tests on strengthening of small size concrete slabs.
Promising results of simple specimen, has encouraged the
research team to perform the next tests using mastered carbon
fibre reinforced fabric. Main tests were performed on
natural scale RC beam. Smart textile proved its efficiency
in both: strengthening and monitoring of strains during
load increase. New strengthening proposal was given 10%
increase of loading capacity and the readings of strain
changes were similar to those obtained in classical methods.
In order to calibrate the prototype and to define range
limits of solution usability, textile sensor was tested in areas
of large deformations (timber beam) and aswell as very
small strains (bridge bearing block). In both cases, the prototype
demonstrated excellent performance in the range
of importance for structural engineering. This paper also
presents an example of use of the smart strengthening in
situ, in a real life conditions.
Knowledge of the electromagnetic properties of textile materials is crucial in order to design wearable antennas. Despite the growth of research studies on textile antennas, the accurate ...characterization of the dielectric properties of the materials is still a challenge due to the intrinsic inhomogeneity and deformability of textiles. In this work, 11 textile materials were characterized using the resonator-based experimental technique. The results obtained using this method have shown that when positioning the roughest face of the Material Under Test (MUT) in contact with the resonator board, the extracted dielectric constant (ɛ
r
) value is lower than the one extracted with this face positioned upside-down. Based on this observation, superficial properties of textiles were investigated. Thus, this paper relates the results of the dielectric characterization to some structural parameters of textiles, such as surface roughness and surface and bulk porosity. The results show that both surface roughness and surface porosity of the samples influence the measurements, through the positioning of the probes. Further, the influence of the positioning of the dielectric material on the performance of textile microstrip antennas was analyzed. For this, 12 prototypes of microstrip patch antennas were developed and tested. The results show that, despite the differences obtained in the characterization when placing the face or reverse-sides of the MUT in contact with the resonator board, the obtained average result of ɛ
r
is well suited to design antennas, ensuring a good performance.
A wideband half-mode substrate-integrated-waveguide cavity-backed slot antenna covering all Unlicensed National Information Infrastructure (U-NII) radio bands (5.15-5.85 GHz) is designed, fabricated, ...and validated. By a half-mode implementation of a multimoded cavity with nonresonant slot, a compact ultrawideband antenna is obtained with very stable radiation characteristics, owing to the excellent antenna/platform isolation. Cork material is applied as antenna substrate, making the proposed antenna suitable for integration into floors or walls. In free-space conditions, an impedance bandwidth of 1.30 GHz (23.7%), a radiation efficiency of 85%, a front-to-back ratio of 15.0 dB, and a maximum gain of 4.3 dBi at 5.50 GHz are measured. Performance is also validated when the antenna is deployed on various dielectric or conducting platforms and underneath different dielectric superstrates. Only the latter slightly detunes the antenna's impedance bandwidth. Yet, the complete frequency band of interest remains covered, owing to additional design margins incorporated in the requirements. Its compactness, unobtrusive integration potential, and stable high performance in different environments make this antenna topology an ideal candidate for Internet of Things applications.
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