56 research outputs found
Development of Textile Antennas for Energy Harvesting
The current socio-economic developments and lifestyle trends indicate an increasing
consumption of technological products and processes, powered by emergent concepts, such as
Internet of Things (IoT) and smart environments, where everything is connected in a single
network. For this reason, wearable technology has been addressed to make the person, mainly
through his clothes, able to communicate with and be part of this technological network.
Wireless communication systems are made up of several electronic components, which over
the years have been miniaturized and made more flexible, such as batteries, sensors, actuators,
data processing units, interconnectors and antennas. Turning these systems into wearable
systems is a demanding research subject. Specifically, the development of wearable antennas
has been challenging, because they are conventionally built on rigid substrates, hindering their
integration into the garment. That is why, considering the flexibility and the dielectric
properties of textile materials, making antennas in textile materials will allow expanding the
interaction of the user with some electronic devices, by interacting through the clothes. The
electronic devices may thus become less invasive and more discrete.
Textile antennas combine the traditional textile materials with new technologies. They emerge
as a potential interface of the human-technology-environment relationship. They are becoming
an active part in the wireless communication systems, aiming applications such as tracking and
navigation, mobile computing, health monitoring and others. Moreover, wearable antennas
have to be thin, lightweight, of easy maintenance, robust, and of low cost for mass production
and commercialization.
In this way, planar antennas, the microstrip patch type, have been proposed for garment
applications, because this type of antenna presents all these characteristics, and are also
adaptable to any surface. Such antennas are usually formed by assembling conductive (patch
and ground plane) and dielectric (substrate) layers. Furthermore, the microstrip patch
antennas, radiate perpendicularly to a ground plane, which shields the antenna radiation,
ensuring that the human body is exposed only to a very small fraction of the radiation.
To develop this type of antenna, the knowledge of the properties of textile materials is crucial
as well as the knowledge of the manufacturing techniques for connecting the layers with glue,
seam, adhesive sheets and others. Several properties of the materials influence the behaviour
of the antenna. For instance, the bandwidth and the efficiency of a planar antenna are mainly
determined by the permittivity and the thickness of the substrate. The use of textiles in
wearable antennas requires thus 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. In general, textiles present a very low dielectric constant, εr, 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.
To explain some influences of the textile material on the performance of the wearable
antennas, this PhD Thesis starts presenting 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. Further,
manufacturing techniques of the textile antennas are described.
The accurate characterization of textile materials to use as a dielectric substrate in wearable
systems is fundamental. However, little information can be found on the electromagnetic
properties of the regular textiles. Woven, knits and nonwovens are inhomogeneous, highly
porous, compressible and easily influenced by the environmental hygrometric conditions,
making their electromagnetic characterization difficult. Despite there are no standard
methods, several authors have been adapting techniques for the dielectric characterization of
textiles. This PhD Thesis focuses on the dielectric characterization of the textile materials,
surveying the resonant and non-resonant methods that have been proposed to characterize the
textile and leather materials. Also, this PhD Thesis summarizes the characterization of textile
materials made through these methods, which were validated by testing antennas that
performed well.
Further a Resonant-Based Experimental Technique is presented. This new method is based on
the theory of resonance-perturbation, extracting the permittivity and loss tangent values based
on the shifts caused by the introduction of a superstrate on the patch of a microstrip antenna.
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 value is lower than the one extracted with this face positioned upside-down. Based
on this observation, superficial properties of textiles were investigated and their influence on
the performance of antennas was analysed.
Thus, this PhD Thesis relates the results of the dielectric characterization to some structural
parameters of textiles, such as surface roughness, superficial and bulk porosities. The results
show that both roughness and superficial 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 analysed. For this, twelve
prototypes of microstrip patch antennas were developed and tested. The results show that,
despite the differences obtained on the characterization when placing the face or reverse-sides of the MUT in contact with the resonator board, the obtained average result of εr is well suited
to design antennas ensuring a good performance.
According to the European Commission Report in 2009, “Internet of Things — An action plan for
Europe”, in the next years, the IoT will be able to improve the quality of life, especially in the
health monitoring field. In the Wireless Body Sensor Network (WBSN) context, the integration
of textile antennas for energy harvesting into smart clothing is a particularly interesting
solution for a continuous wirelessly feed of the devices. Indeed, in the context of wearable
devices the replacement of batteries is not easy to practice. A specific goal of this PhD Thesis
is thus to describe the concept of the energy harvesting and then presents a survey of textile
antennas for RF energy harvesting. Further, a dual-band printed monopole textile antenna for
electromagnetic energy harvesting, operating at GSM 900 and DCS 1800 bands, is also proposed.
The antenna aims to harvest energy to feed sensor nodes of a wearable health monitoring
system. The gains of the antenna are around 1.8 dBi and 2.06 dBi allied with a radiation
efficiency of 82% and 77.6% for the lowest and highest frequency bands, respectively.
To understand and improve the performance of the proposed printed monopole textile antenna,
several manufacturing techniques are tested through preliminary tests, to identify promising
techniques and to discard inefficient ones, such as the gluing technique. Then, the influence
of several parameters of the manufacturing techniques on the performance of the antenna are
analysed, such as the use of steam during lamination, the type of adhesive sheet, the
orientation of the conductive elements and others. For this, seven prototypes of the printed
monopole textile antenna were manufactured by laminating and embroidering techniques.
The measurement of the electrical surface resistance, Rs, has shown that the presence of the
adhesive sheet used on the laminating process may reduce the conductivity of the conductive
materials. Despite that, when measuring the return loss of printed monopole antennas
produced by lamination, the results show the antennas have a good performance. The results
also show that the orientation of the conductive fabric does not influence the performance of
the antennas. However, when testing embroidered antennas, the results show that the
direction and number of the stitches in the embroidery may influence the performance of the
antenna and should thus be considered during manufacturing.
The textile antennas perform well and their results support and give rise to the new concept
of a continuous substrate to improve the integration of textile antennas into clothing, in a more
comfortable and pleasure way. A demonstrating prototype, the E-Caption: Smart and
Sustainable Coat, is thus presented. In this prototype of smart coat, the 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. The results obtained testing the antenna before and after its integration into cloth,
show that the integration does not affect the behaviour of the antenna. Even on the presence
of the human body the antenna is able to cover the proposed resonance frequencies (GSM 900
and DCS 1800 bands) with the radiation pattern still being omnidirectional. At last, the exponential growth in the wearable market boost the industrialization process of
manufacturing textile antennas. As this research shows, the patch of the antennas can be easily
and efficiently cut, embroidered or screen printed by industrial machines. However, the
conception of a good industrial substrate that meets all the mechanical and electromagnetic
requirements of textile antennas is still a challenge. Following the continuous substrate
concept presented and demonstrated through the E-Caption, a new concept is proposed: the
continuous Substrate Integrating the Ground Plane (SIGP). The SIGP is a novel textile material
that integrates the dielectric substrate and the conductive ground plane in a single material,
eliminating one laminating process. Three SIGP, that are weft knitted spacer fabrics having one
conductive face, were developed in partnership with the Borgstena Textile Portugal Lda,
creating synergy between research in the academy and industry. The results of testing the
performance of the SIGP materials show that the integration of the ground plane on the
substrate changes the dielectric constant of the material, as a consequence of varying the
thickness. Despite this, after the accurate dielectric and electrical characterization, the SIGP
I material has shown a good performance as dielectric substrate of a microstrip patch antenna
for RF energy harvesting. This result is very promising for boosting the industrial fabrication of
microstrip patch textile antennas and their mass production and dissemination into the IoT
network, guiding future developments of smart clothing and wearables.Os atuais desenvolvimentos socioeconómicos e tendências de estilo de vida apontam para um
crescimento do consumo de produtos e processos tecnológicos, impulsionado por conceitos
emergentes como a Internet das Coisas, onde tudo tudo está conectado em uma única rede.
Por esta razão, as tecnologias usáveis (wearable) estão a afirmar-se propondo soluções que
tornam o utilizador possivelmente através das suas roupas, capaz de comunicar com e fazer
parte desta rede.
Os sistemas de comunicações sem fios são constituídos por diversos componentes eletrónicos,
que com o passar dos anos foram sendo miniaturizados e fabricados em materiais flexíveis, tais
como as baterias, os sensores, as unidades de processamento de dados, as interconexões e as
antenas. Tornar os sistemas de comunicações sem fios em sistemas usáveis requer trabalho de
investigação exigente. Nomeadamente, o desenvolvimento de antenas usáveis tem sido um
desafio, devido às antenas serem tradicionalmente desenvolvidas em substratos rígidos, que
dificultam a sua integração no vestuário. Dessa forma, considerando a flexibilidade e as
propriedades dielétricas dos materiais têxteis, as antenas têxteis trazem a promessa de
permitir a interacção dos utilizadores com os dispositivos eletrónicos através da roupa,
tornando os dispositivos menos invasivos e mais discretos.
As antenas têxteis combinam os materiais têxteis tradicionais com novas tecnologias e emergem
assim como uma potencial interface de fronteira entre seres humanos-tecnologias-ambientes.
Expandindo assim a interação entre o utilizador e os dispositivos eletrónicos ao recurso do
vestuário. Assim, através das antenas têxteis, o vestuário torna-se uma parte ativa nos sistemas
de comunicação sem fios, visando aplicações como rastreamento e navegação, computação
móvel, monitorização de saúde, entre outros. Para isto, as antenas para vestir devem ser finas,
leves, de fácil manutenção, robustas e de baixo custo para produção em massa e
comercialização.
Desta forma, as antenas planares do tipo patch microstrip têm sido propostas para aplicações
em vestuário, pois apresentam todas estas características e também são adaptáveis a qualquer
superfície. Estas antenas são geralmente formadas pela sobreposição de camadas condutoras
(elemento radiante e plano de massa) e dielétricas (substrato). Além disso, as antenas patch
microstrip irradiam perpendicularmente ao plano de massa, que bloqueia a radiação da antena,
garantindo que o corpo humano é exposto apenas a uma fração muito pequena da radiação.
Para desenvolver este tipo de antena, é crucial conhecer as propriedades dos materiais têxteis,
bem como as técnicas de fabricação para conectar as camadas, com cola, costuras, folhas
adesivas, entre outros. Diversas propriedades dos materiais influenciam o comportamento da
antena. Por exemplo, a permitividade e a espessura do substrato determinam a largura de banda e a eficiência de uma antena planar. O uso de têxteis em antenas usáveis requer assim
uma caracterização precisa das suas propriedades. Os têxteis condutores elétricos são materiais
específicos que estão disponíveis comercialmente em diversas formas e têm sido utilizados com
sucesso para fabricar o elemento radiante e o plano de massa das antenas. Para fabricar o
substrato dielétrico têm sido utilizados materiais têxteis convencionais.
Geralmente, os materiais têxteis apresentam uma constante dielétrica (εr) muito baixa, o que
reduz as perdas de ondas superficiais e aumenta a largura de banda da antena. No entanto, os
materiais têxteis estão constantemente a trocar moléculas de água com o ambiente em que
estão inseridos, o que afeta as suas propriedades eletromagnéticas. Além disso, os tecidos e os
outros materiais têxteis planares são materiais porosos, anisotrópicos e compressíveis, cuja
espessura e densidade variam sob muito baixas pressões. Portanto, é importante saber como
estas grandezas e características estruturais influenciam o comportamento da antena, de forma
a minimizar os efeitos indesejáveis.
Para explicar algumas das influências do material têxtil no desempenho das antenas usáveis,
esta Tese de Doutoramento começa por fazer o estado da arte sobre os pontos-chave para o
desenvolvimento de antenas têxteis, desde a escolha dos materiais têxteis até ao processo de
fabrico da antena. Além disso, a tese identifica e apresenta uma análise dos materiais têxteis
e técnicas de fabricação que têm sido utilizados e referidos na literatura.
A caracterização rigorosa dos materiais têxteis para usar como substrato dielétrico em sistemas
usáveis é fundamental. No entanto, pouca informação existe sobre a caracterização das
propriedades eletromagnéticas dos têxteis vulgares. Como já referido, os tecidos, malhas e
não-tecidos são materiais heterogéneos, altamente porosos, compressíveis e facilmente
influenciados pelas condições higrométricas ambientais, dificultando a sua caracterização
eletromagnética. Não havendo nenhum método padrão, vários autores têm vindo a adaptar
algumas técnicas para a caracterização dielétrica dos materiais têxteis. Esta Tese de
Doutoramento foca a caracterização dielétrica dos materiais têxteis, revendo os métodos
ressonantes e não ressonantes que foram propostos para caracterizar os materiais têxteis e o
couro. Além disso, esta Tese de Doutoramento resume a caracterização de dieléctricos têxteis
feita através dos métodos revistos e que foi validada testando antenas que apresentaram um
bom desempenho.
No seguimento da revisão, apresenta-se uma Técnica Experimental Baseada em Ressonância.
Esta nova técnica baseia-se na teoria da perturbação de ressonância, sendo a permitividade e
tangente de perda extraídas com base nas mudanças de frequência causadas pela introdução
de um superstrato no elemento radiante de uma antena patch microstrip. Os resultados de
caracterização obtidos através deste método revelam que, ao posicionar a face mais rugosa do
material em teste em contato com a placa de ressonância, o valor da constante dielétrica
extraída é inferior ao valor extraído quando esta face é colocada ao contrário. Com base nesta
observação, as propriedades estruturais da superfície dos materiais têxteis foram investigadas
e a sua influência no desempenho das antenas foi analisada. Assim, esta Tese de Doutoramento relaciona os resultados da caracterização dielétrica com
alguns parâmetros estruturais dos materiais, como rugosidade da superfície, porosidades
superficial e total. Os resultados mostram que tanto a rugosidade como a porosidade superficial
das amostras influenciam os resultados, que dependem assim do posicionamento do material
que está a ser testado. Também foi analisada a influência do posicionamento do material
dielétrico na performance das antenas têxteis tipo patch microstrip. Para isso, foram
desenvolvidos e testados doze protótipos de antenas patch microstrip. Os resultados mostram
que, apesar das diferenças observadas durante o processo de caracterização, o valor médio da
permitividade é adequado para a modelação das antenas, garantindo um bom desempenho.
De acordo com o relatório da Comissão Europeia, “Internet das Coisas - Um plano de ação para
a Europa”, emitido em 2009, nos próximos anos a Internet das Coisas poderá melhorar a
qualidade de vida das pessoas, nomeadamente pela monitorização da saúde. No contexto das
Redes de Sensores Sem Fios do Corpo Humano, a integração de antenas têxteis para recolha de
energia em roupas inteligentes é uma solução particularmente interessante, pois permite uma
alimentação sem fios e contínua dos dispositivos. De fato, nos dispositivos usáveis a substituição
de baterias não é fácil de praticar. Um dos objetivos específicos desta Tese de Doutoramento
é, portanto, descrever o conceito de recolha de energia e apresentar o estado da arte sobre
antenas têxteis para recolha de energia proveniente da Rádio Frequência (RF). Nesta tese, é
também proposta uma antena impressa do tipo monopolo de dupla banda, fabricada em
substrato têxtil, para recolha de energia eletromagnética, operando nas bandas GSM 900 e DCS
1800. A antena visa recolher energia para alimentar os nós de sensores de um sistema usável
para monitorização da saúde. Os ganhos da antena apresentada foram cerca de 1.8 dBi e 2.06
dBi, aliados a uma eficiência de radiação de 82% e 77.6% para as faixas de frequência mais
baixa e alta, respetivamente.
Para entender e melhorar o desempenho da antena impressa tipo monopolo de dupla banda em
substrato têxtil, várias técnicas de fabrico foram testadas através de testes preliminares, de
forma a identificar as técnicas promissoras e a descartar as ineficientes, como é o caso da
técnica de colagem. De seguida, analisou-se a influência de vários parâmetros das técnicas de
fabrico sobre o desempenho da antena, como o uso de vapor durante a laminação, o tipo de
folha adesiva, a orientação dos elementos irradiantes e outros. Para isto, sete protótipos da
antena têxtil monopolar impressa foram fabricados por técnicas de laminação e bordado.
As medições da resistência elétrica superficial, Rs, mostrou que a presença da folha adesiva
usada no processo de laminagem pode reduzir a condutividade dos materiais condutores. Apesar
disso, ao medir o S11 das antenas impressas tipo monopolo produzidas por laminagem, os
resultados mostram que as antenas têm uma boa adaptação da impedância. Os resultados
também mostram que a orientação do tecido condutor, neste caso um tafetá, não influencia o
desempenho das antenas. No entanto, ao testar antenas bordadas, os resultados mostram que
a direção e o número de pontos no bordado podem influenciar o desempenho da antena e,
portanto, estas são características que devem ser consideradas durante a fabricação. De um modo geral, as antenas têxteis funcionam bem e seus resultados suportam e dão origem
ao um novo conceito de substrato contínuo para melhorar a integração de antenas têxteis no
vestuário, de maneira mais confortável e elegante. A tese apresenta um protótipo
demonstrador deste conceito, o E-Caption: A Smart and Sustainable Coat. Neste protótipo de
casaco inteligente, a antena impressa está totalmente integrada, pois o seu substrato dielétrico
é o próprio mat
System design and performance analysis of wireless body area networks
One key solution to provide affordable and proactive healthcare facilities to overcome the fast world population growth and a shortage of medical professionals is through health monitoring systems capable of early disease detection and real-time data transmission leading to considerable improvements in the quality of human life. Wireless body area networks (WBANs) are proposed as promising approaches to providing better mobility and flexibility experience than traditional wired medical systems by using low-power, miniaturised sensors inside, around, or off the human body and are employed to monitor physiological signals. However, the design of reliable and energy efficient in-body communication systems is still a major research challenge since implant devices are characterised by strict requirements on size, energy consumption and safety. Moreover, there is still no agreement regarding QoS support in WBANs.
The first part of this work concentrates on the design and performance evaluation of WBAN communication systems involving the ‘in-body to in-body’ and ‘in-body to on-body’ scenarios. The essential step is to derive the statistical WBAN path loss (PL) models, which characterise the signal propagation energy loss transmitting via intra-body region. Moreover, from the point of view of human body safety evaluation, the obtained specific absorption rate (SAR) values are compared with the latest Institute of Electrical and Electronics Engineers (IEEE) 802.15.6 Task Group technical standard and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) safety guidelines. Link budget analysis is then presented using a range of energy-efficient modulation schemes, and the results are given including the transmission distance, data rate and transmitting power in individual sections. On the other hand, major quality of service (QoS) support challenges in WBANs are discussed and investigated. To achieve higher lifetime and lower network energy consumption, different data routing protocol methods, including incremental relaying and the two-relay based routing technique are taken into account. A set of key QoS metrics for linear mathematical models is given along with the related subjective functions. The incremental relaying routing protocol promises significant enhancements in in-body WBAN network lifetime by minimising the overall communication distance while the two-relay based routing method achieves better performance in terms of emergency data transmission and high traffic condition, QoS-aware WBANs design. Moreover, to handle real-time high data transmission applications such as capsule endoscope image transmission, a flexible QoS-aware wireless body area sensor networks (WBASNs) model is proposed and evaluated that can bring novel solutions for a realistic multi-user hospital environment regarding information packet collision probability, manageable numbers of sensor nodes and a wide range of data rates
Innovative energy-efficient wireless sensor network applications and MAC sub-layer protocols employing RTS-CTS with packet concatenation
of energy-efficiency as well as the number of available applications. As a consequence there
are challenges that need to be tackled for the future generation of WSNs. The research work
from this Ph.D. thesis has involved the actual development of innovative WSN applications contributing
to different research projects. In the Smart-Clothing project contributions have been
given in the development of a Wireless Body Area Network (WBAN) to monitor the foetal movements
of a pregnant woman in the last four weeks of pregnancy. The creation of an automatic
wireless measurement system for remotely monitoring concrete structures was an contribution
for the INSYSM project. This was accomplished by using an IEEE 802.15.4 network enabling for
remotely monitoring the temperature and humidity within civil engineering structures. In the
framework of the PROENEGY-WSN project contributions have been given in the identification
the spectrum opportunities for Radio Frequency (RF) energy harvesting through power density
measurements from 350 MHz to 3 GHz. The design of the circuits to harvest RF energy
and the requirements needed for creating a WBAN with electromagnetic energy harvesting and
Cognitive Radio (CR) capabilities have also been addressed. A performance evaluation of the
state-of-the art of the hardware WSN platforms has also been addressed. This is explained by
the fact that, even by using optimized Medium Access Control (MAC) protocols, if the WSNs
platforms do not allow for minimizing the energy consumption in the idle and sleeping states,
energy efficiency and long network lifetime will not be achieved.
The research also involved the development of new innovative mechanisms that tries and solves
overhead, one of the fundamental reasons for the IEEE 802.15.4 standard MAC inefficiency. In
particular, this Ph.D. thesis proposes an IEEE 802.15.4 MAC layer performance enhancement by
employing RTS/CTS combined with packet concatenation. The results have shown that the use
of the RTS/CTS mechanism improves channel efficiency by decreasing the deferral time before
transmitting a data packet. In addition, the Sensor Block Acknowledgment MAC (SBACK-MAC)
protocol has been proposed that allows the aggregation of several acknowledgment responses
in one special Block Acknowledgment (BACK) Response packet. Two different solutions are
considered. The first one considers the SBACK-MAC protocol in the presence of BACK Request
(concatenation) while the second one considers the SBACK-MAC in the absence of BACK Request
(piggyback). The proposed solutions address a distributed scenario with single-destination and
single-rate frame aggregation. The throughput and delay performance is mathematically derived
under both ideal conditions (a channel environment with no transmission errors) and non
ideal conditions (a channel environment with transmission errors). An analytical model is proposed,
capable of taking into account the retransmission delays and the maximum number of
backoff stages. The simulation results successfully validate our analytical model. For more
than 7 TX (aggregated packets) all the MAC sub-layer protocols employing RTS/CTS with packet
concatenation allows for the optimization of channel use in WSNs, v8-48 % improvement in the
maximum average throughput and minimum average delay, and decrease energy consumption
A Sum-Utility Maximization Approach for Fairness Resource Allocation in Wireless Powered Body Area Networks
Wireless body area networks (WBANs) are essential for monitoring physiological signals of the human body, but the lifetime of WBANs is limited by battery longevity and it is not convenient or feasible for replacing the batteries of the sensors. The newly emerged energy-harvesting technology provides the potential to break the battery limitation of WBANs. However, the radio resource of a WBAN should be carefully scheduled for the wireless power transfer links and wireless information transmission links; otherwise, severely unfair resource allocation could be incurred due to the difference of channel qualities of the sensors. In this paper, we propose a marginal utility theoretic method to allocate the radio resource to the on-/in-body sensors in a fair and efficient manner. Especially, we consider that the sensors are wireless powered by multiple pre-installed radio-frequency energy sources. First, the utility function for a sensor node is proposed, which can map the achievable throughput to a satisfaction level of network QoS. Then, the fairness resource allocation among the sensor nodes is modeled as a sum-utility maximization problem. By using the dual decomposition method, the optimal solution to the proposed problem can finally be solved in the closed form. In comparison with the sum-throughput maximization and common-throughput maximization methods, the simulation results show that the proposed sum-utility maximization method can bring a fair throughput allocation for the sensors with different channel conditions, and the performance loss to the sum-throughput maximization method is small, while the sum-throughput maximization method is extremely unfair
The 3rd International Conference on the Challenges, Opportunities, Innovations and Applications in Electronic Textiles
This reprint is a collection of papers from the E-Textiles 2021 Conference and represents the state-of-the-art from both academia and industry in the development of smart fabrics that incorporate electronic and sensing functionality. The reprint presents a wide range of applications of the technology including wearable textile devices for healthcare applications such as respiratory monitoring and functional electrical stimulation. Manufacturing approaches include printed smart materials, knitted e-textiles and flexible electronic circuit assembly within fabrics and garments. E-textile sustainability, a key future requirement for the technology, is also considered. Supplying power is a constant challenge for all wireless wearable technologies and the collection includes papers on triboelectric energy harvesting and textile-based water-activated batteries. Finally, the application of textiles antennas in both sensing and 5G wireless communications is demonstrated, where different antenna designs and their response to stimuli are presented
Assessment of worn textile antennas’ exposure on the physiological parameters and well-being of adults
This paper presents the assessment of short-term wireless body area network (WBAN) exposure, which is operated at the industrial, scientific, and medical (ISM) band (2.45 GHz) in the vicinity of the human body. The experiment utilizes two popular textile antenna topologies, a planar monopole and a patch antenna as the radiating sources. The objective of this experiment is to investigate whether the exposure from WBAN may influence the physiological parameters (body temperature, blood pressure, and heart rate) and the well-being of the wearer. Counter-balanced, crossover, and the single-blind method was applied in the experimental setup. P-value is the probability value, under the assumption of no effect or no difference (the null hypothesis) of obtaining a result equal to or more extreme than what was actually observed. If P<; 0.05, it indicates that P-value will be less than the level of significance. Thus, the null hypothesis (no effect or no difference) can be rejected, and it can be concluded that there exist effects to the respondents. The results showed that there is statistically no significant difference between the active exposure and the Sham (no exposure) which may affect the physiological parameters and well-being of the wearers, with P>0.05, which failed to reject the null hypothesis (no effect)
A survey on wireless body area networks for eHealthcare systems in residential environments
The progress in wearable and implanted health monitoring technologies has strong potential to alter the future of healthcare services by enabling ubiquitous monitoring of patients. A typical health monitoring system consists of a network of wearable or implanted sensors that constantly monitor physiological parameters. Collected data are relayed using existing wireless communication protocols to the base station for additional processing. This article provides researchers with information to compare the existing low-power communication technologies that can potentially support the rapid development and deployment of WBAN systems, and mainly focuses on remote monitoring of elderly or chronically ill patients in residential environments
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