Proetex: protective e-textiles to enhance the safety of emergency/disaster operators: current state of the projects' achievements

Proetex is a European Integrated Project dedicated to the realization of a micro- and nano-technology-based wearable equipment for emergency operators. During the first 3 years of work, two different and progressively improved versions of a complete “smart” uniform for fire-fighters and emergency rescuers have been realized. These garments aim at monitoring both physiological parameters, position and posture of the operators and the presence of external potential sources of danger and to send these data to a remote coordinating unit. In the following, the main issues of the design and realization will be described and discussed

Electrocardiogram and Impedance Pneumography Measurement Module Design for Textile-Integrated Solution

A wearable electronics is a quickly broadening category in sport, wellbeing and entertainment products. Also a fully textile-integrated electronics is used increasingly to improve the user experience. The medical industry is interested to exploit especially the latter technology for a supported long-term home care. The problem is, there are only wellbeing promoting textile-integrated electronics at the moment. These products recommend for example how to prevent an injury, but do not provide the actual diagnostic value. Purpose of this master´s thesis was to increase knowledge of the biomedical instrumentation about diagnostics textile-integrated electronics – especially designed for long-term home monitoring of the elderly. For achieving this matter, into shirt integrated an electrocardiography (ECG) and impedance pneumography (IP) measurement module will be developed as a part of the Disappearing Sensors (DISSE) project. Preparation, like technical designing and functionality testing, have been made during this thesis for fulfilling described target. The functionality testing was implemented from three point of views: electrodes, measurement position, and measuring techniques for the ECG and IP. As electrodes were used commercial disposable electrodes, textile electrodes, and printed electrodes. Different measurement positions were laying, sitting, standing and walking slow and fast. As measurement techniques, 2- and 4-electrode measuring methods were compared by using commercial evaluation board. The work also considered a choose of the shirt and its final form in the prototype, which textile-integrated version will be completed during Autumn 2016. From electrodes the most stable results were gathered with disposal ones. However, the skin irritation caused by these electrodes is not suitable for a long-term monitoring. For the textile and printed electrodes skin irritation did not seem to be a problem. Random instabilities of the textile electrodes were reason why the printed electrodes were chosen to be the best alternative. Measuring positions, excluding walking, fulfilled the minimum goal to detect pulse and breathing. In walking tests heart and respiration rates can be detected, despite occasional errors, only with disposal electrodes. In order to achieve the this with printed electrodes, the skin-electrode-contact should be improved. From two measuring techniques the 4-electrode measuring method had worse signal quality, but pulse and breathing were detected with more accuracy compared to 2-electrode measuring method

Impedance pneumography in respiration monitoring

Respiration monitoring provides health care professionals essential information about patients’ condition and can help diagnosing pulmonary diseases. The most reliable methods for assessment are obtrusive and include masks and can require performing manoeuvres that limit the usability with uncooperative patients like children or unconscious. In contrast, in hospital wards respiration rate and effort are intermittently assessed only visually during rounds at patient rooms leading to poor frequency of recording. Hence, early signs of deterioration in condition are often missed. Bioimpedance have been studied as a continuous and unobtrusive method for respiration monitoring. The technique is based on differences in electrical properties of tissues. A small current is fed through the body and voltage across is measured. Respiration and cardiac functions affect current flow and thus change the total impedance. Frequency of the applied current and geometry of the thorax cause also variation in the signal. When using bioimpedance to assess respiratory functions the method is called impedance pneumography. Despite of being an established and widely used method, there is ongoing research to improve its performance. One major challenge is its susceptibility to movement. However, signal processing algorithms advance all the time making development of wearable applications also possible. In this study, respiration is measured with bioimpedance and compared to signal from pneumotachometer. Two different electrode configurations were used to evaluate their performance in different positions, in supine, sitting and walking stationary. The study protocol included alternation between thoracic and diaphragmatic breathing at different depths. Respiration rates were determined with peak detection, advanced counting and Fast Fourier Transform (FFT) algorithms and their performances were compared. The results show that respiration rates were most accurately measured during supine position with Mason-Likar arm electrodes. No significant differences between thoracic and diaphragmatic breathing were seen whereas shallow breathing was occasionally hard to detect. The peak detection algorithm performed best having mean absolute error (MAE) of 0.47, 1.12 and 1.23 breaths per minute (bpm) for lying, sitting and walking, respectively. However, MAE values of FFT method were not comparable to other methods in most of the cases. Comparison between electrode configurations is not straightforward, as the measurements were not made simultaneously. Also, the study involved only relatively young and healthy subjects which are not the most abundant age group needing monitoring at hospitals. When considering patient monitoring applications, future studies should involve subjects with wider range of characteristics to obtain more definitive results about the performance of the impedance pneumography.Hengitystä monitoroimalla saadaan tärkeää informaatiota potilaan terveydentilasta sekä apua keuhkosairauksien diagnosointiin. Tällä hetkellä luotettavimmat menetelmät häiritsevät luonnollista hengitystä ja saattavat vaatia erityisiä hengityskuvioita, jotka eivät onnistu yhteistyökyvyttömiltä potilailta kuten lapsilta tai vakavasti sairailta. Toisaalta sairaaloiden osastoilla hengitystaajuutta ja hengityksen vaikeutta saatetaan ajoittain arvioida ainoastaan visuaalisesti tarkastuskierrosten aikana, jolloin tuloksien väli saattaa venyä pitkäksi eikä muutoksia huomata ajoissa. Bioimpedanssimenetelmä tarjoaa keinon jatkuvaan hengityksen monitorointiin häiritsemättä sitä. Tekniikka perustuu kudosten erilaiseen kykyyn vastustaa sähkövirran kulkua, ja sen avulla voidaan saada monesta kehontoiminnosta tietoa. Hengityksen analysoinnissa menetelmästä käytetään nimitystä impedanssipneumografia. Käytännössä kehoon syötetään pieniamplitudista virtaa ja mitataan jännitettä mittapisteiden välillä. Hengityksen aiheuttamat muutokset vaikuttavat sähkövirran kulkuun ja näin ollen muuttavat impedanssisignaalia. Myös syötetyn virran taajuus sekä rintakehän muoto vaikuttavat havaittuun impedanssiin. Vaikka menetelmä on jo vakiintunut ja laajalti käytössä, tutkijat pyrkivät jatkuvasti parantamaan bioimpedanssin mittaustekniikkaa. Yksi menetelmän heikkouksista on sen alttius liikkeestä aiheutuville häiriöille. Signaalinkäsittelymenetelmät kehittyvät kuitenkin jatkuvasti mahdollistaen myös tutkimuksen bioimpedanssin käytöstä puettavissa laitteissa. Tässä tutkimuksessa mitattiin hengitystä bioimpedanssin avulla ja verrattiin saatua signaalia pneumotakometrillä kerättyyn referenssiin. Mittauksissa käytettiin kahta eri elektrodien sijoittelua ja arvioitiin niiden toimivuutta eri asennoissa: selinmakuulta, istualtaan sekä paikallaan kävellessä. Mittausten aikana tutkittavat hengittivät eri syvyyksillä ja vaihtelivat pallea- ja rintahengityksen välillä. Saadusta datasta arvioitiin hengitystaajuutta peak detection, advanced counting ja Fast Fourier Transform -algoritmeilla ja vertailtiin niiden toimivuutta. Tutkimuksessa havaittiin, että luotettavin arvio hengitystaajuudesta saatiin makuuasennossa Mason-Likar käsielektrodeilta mitattaessa. Pallea- ja rintahengityksen välillä ei havaittu merkittäviä eroja, kun taas pinnallista hengitystä oli ajoittain vaikea havaita impedanssisignaalista. Peak detection -algoritmin suoriutui parhaiten käytetyistä metodeista. Tällä menetelmällä keskimääräinen absoluuttinen virhe oli 0.47 hengitystä minuutissa (bpm) makuulta, 1.12 bpm istualtaan ja 1.23 bpm kävellessä. FFT-algoritmilla ei saatu vertailukelpoisia arvoja hengitystiheydestä johtuen todennäköisesti liian suuresta ikkunan pituudesta. Elektrodipaikkojen vaikutusta on hankala arvioida suoraviivaisesti, sillä mittauksia ei tehty samanaikaisesti. Tutkimuksessa oli mukana ainoastaan suhteellisen nuoria ja hyväkuntoisia henkilöitä. Tällaisilta tutkittavilta mahdollisesti saadaan parempia tuloksia kuin ikääntyneiltä tai ylipainoisilta. Potilasmonitorisovelluksia ajatellen seuraaviin tutkimuksiin kannattaisi ottaa mukaan ominaisuuksiltaan laajempi joukko tutkittavia, jotta saataisiin kattavampi näyttö impedanssipneumografian suorituskyvyst

Wearable contactless respiration sensor based on multi-material fibers integrated into textile

In this paper, we report on a novel sensor for the contactless monitoring of the respiration rate, made from multi-material fibers arranged in the form of spiral antenna (2.45 GHz central frequency). High flexibility of the used composite metal-glass-polymer fibers permits their integration into a cotton t-shirt without compromising comfort or restricting movement of the user. At the same time, change of the antenna geometry, due to the chest expansion and the displacement of the air volume in the lungs, is found to cause a significant shift of the antenna operational frequency, thus allowing respiration detection. In contrast with many current solutions, respiration is detected without attachment of the electrodes of any kind to the user’s body, neither direct contact of the fiber with the skin is required. Respiration patterns for two male volunteers were recorded with the help of a sensor prototype integrated into standard cotton t-shirt in sitting, standing, and lying scenarios. The typical measured frequency shift for the deep and shallow breathing was found to be in the range 120–200 MHz and 10–15 MHz, respectively. The same spiral fiber antenna is also shown to be suitable for short-range wireless communication, thus allowing respiration data transmission, for example, via the Bluetooth protocol, to mobile handheld devices

Continuous monitoring of vital parameters for clinically valid assessment of human health status

Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Sinais e Imagens Médicas) Universidade de Lisboa, Faculdade de Ciências, 2019The lack of devices suitable for acquiring accurate and reliable measures of patients' physiolog-ical signals in a remote and continuous manner together with the advances in data acquisition technol-ogies during the last decades, have led to the emergence of wearable devices for healthcare. Wearable devices enable remote, continuous and long-term health monitoring in unattended setting. In this con-text, the Swiss Federal Laboratories for Material Science and Technology (Empa) developed a wearable system for long-term electrocardiogram measurements, referred to as textile belt. It consists of a chest strap with two embroidered textile electrodes. The validity of Empa’s system for electrocardiogram monitoring has been proven in a clinical setting. This work aimed to assess the validity of the textile belt for electrocardiogram monitoring in a home setting and to supplement the existing system with sensors for respiratory monitoring. Another objective was to evaluate the suitability of the same weara-ble, as a multi-sensor system, for activity monitoring. A study involving 12 patients (10 males and 2 females, interquartile range for age of 48–59 years and for body mass indexes of 28.0–35.5 kg.m-2) with suspected sleep apnoea was carried out. Overnight electrocardiogram was measured in a total of 28 nights. The quality of recorded signals was assessed using signal-to-noise ratio, artefacts detection and Poincaré plots. Study data were compared to data from the same subjects, acquired in the clinical setting. For respiratory monitoring, optical fibre-based sensors of different geometries were integrated into the textile belt. Signal processing algorithms for breathing rate and tidal volume estimation based on respiratory signals acquired by the sensors were developed. Pilot studies were conducted to compare the different approaches for respiratory monitoring. The quality of respiratory signals was determined based on signal segments “sinusoidality”, evaluated through the calculation of the cross-correlation between signal segments and segment-specific reference waves. A method for accelerometry-based lying position recognition was proposed, and the proof of concept of activity intensity classification through the combination of subjects’ inertial acceleration, heart rate and breathing rate data, was presented. Finally, a study with three participants (1 male and 2 females, aged 21 ± 2 years, body mass index of 20.3 ± 1.5 kg.m-2) was conducted to assess the validity of the textile belt for respiratory and activity monitoring. Electrocardiogram signals acquired by the textile belt in the home setting were found to have better quality than the data acquired by the same device in the clinical setting. Although a higher artefact percentage was found for the textile belt, signal-to-noise ratio of electrocardiogram signals recorded by the textile belt in the home setting was similar to that of signals acquired by the gel electrodes in the clinical setting. A good agreement was found between the RR-intervals derived from signals recorded in home and clinical settings. Besides, for artefact percentages greater than 3%, visual assessment of Poincaré plots proved to be effective for the determination of the primary source of artefacts (noise or ectopic beats). Acceleration data allowed posture recognition (i.e. lying or standing/sitting, lying position) with an accuracy of 91% and positive predictive value of 80%. Lastly, preliminary results of physical activity intensity classification yielded high accuracy, showing the potential of the proposed method. The textile belt proved to be appropriate for long-term, remote and continuous monitoring of subjects’ physical and physiological parameters. It can monitor not only electrocardiogram, but also breathing rate, body posture and physical activity intensity, having the potential to be used as tool for disease prediction and diagnose support.Contexto: A falta de dispositivos adequados para a monitorização de sinais fisiológicos de um modo remoto e contínuo, juntamente com avanços tecnológicos na área de aquisição de dados nas últimas décadas, levaram ao surgimento de wearable devices, i.e. dispositivos vestíveis, no sector da saúde. Wearable devices possibilitam a monitorização do estado de saúde, de uma forma remota, contínua e de longa duração. Quando feito em ambiente domiciliar, este tipo de monitorização (i.e. contínua, remota e de longa duração) tem várias vantagens: diminui a pressão posta sobre o sistema de saúde, reduz despesas associadas ao internamento e acelera a resposta a emergências, permitindo deteção precoce e prevenção de condições crónicas. Neste contexto, a Empa, Laboratórios Federais Suíços de Ciência e Tecnologia de Materiais, desenvolveu um sistema vestível para a monitorização de eletrocardiograma de longa duração. Este sistema consiste num cinto peitoral com dois elétrodos têxteis integrados. Os elétrodos têxteis são feitos de fio de polietileno tereftalato revestido com prata e uma ultrafina camada de titânio no topo. De modo a garantir a aquisição de sinais de alta qualidade, o cinto tem nele integrado um reservatório de água que liberta vapor de água para humidificar os elétrodos. Este reservatório per-mite a monitorização contínua de eletrocardiograma por 5 a 10 dias, sem necessitar de recarga. A vali-dade do cinto para a monitorização de eletrocardiograma em ambiente clínico já foi provada. Objetivo: Este trabalho teve por objetivo avaliar a validade do cinto para a monitorização de eletrocar-diograma em ambiente domiciliar e complementar o sistema existente com sensores para monitorização respiratória. Um outro objetivo foi analisar a adequação do cinto, como um sistema multisensor, para monitorização da atividade física. Métodos: Um estudo com 12 pacientes com suspeita de apneia do sono (10 homens e 2 mulheres, am-plitude interquartil de 48–59 anos para a idade e de 28.0–35.5 kg.m-2 para o índice de massa corporal) foi conduzido para avaliar a qualidade do sinal de eletrocardiograma medido em ambiente domiciliar. O sinal de eletrocardiograma dos pacientes foi monitorizado continuamente, num total de 28 noites. A qualidade dos sinais adquiridos foi analisada através do cálculo da razão sinal-ruído; da deteção de ar-tefactos, i.e., intervalos RR com um valor inviável de um ponto de vista fisiológico; e de gráficos de Poincaré, um método de análise não linear da distribuição dos intervalos RR registados. Os dados ad-quiridos neste estudo foram comparados com dados dos mesmos pacientes, adquiridos em ambiente hospitalar. Para a monitorização respiratória, sensores feitos de fibra óptica foram integrados no cinto. Al-gorítmicos para a estimar a frequência respiratória e o volume corrente dos sujeitos tendo por base o sinal medido pelas fibras ópticas foram desenvolvidos neste trabalho. As diferentes abordagens foram comparadas através de estudos piloto. Diferentes métodos para avaliação da qualidade do sinal adquirido foram sugeridos. Um método de reconhecimento da postura corporal através do cálculo de ângulos de orientação com base na aceleração medida foi proposto. A prova de conceito da determinação da intensidade da atividade física pela combinação de informações relativas á aceleração inercial e frequências cardíaca e respiratória dos sujeitos, é também apresentada neste trabalho. Um estudo foi conduzido para avaliar a validade do cinto para monitorização da respiração e da atividade física. O estudo contou com 10 parti-cipantes, dos quais 3 vestiram o cinto para monitorização da respiração (1 homem e 2 mulheres, idade 21 ± 2 anos, índice de massa corporal 20.3 ± 1.5 kg.m-2). Resultados: O estudo feito com pacientes com suspeita de apneia do sono revelou que os sinais eletro-cardiográficos adquiridos pelo cinto em ambiente domiciliar foram de melhor qualidade que os sinais adquiridos pelo mesmo dispositivo em ambiente hospitalar. Uma percentagem de artefacto de 2.87% ±4.14% foi observada para os dados adquiridos pelos elétrodos comummente usados em ambiente hospi-talar, 7.49% ± 10.76% para os dados adquiridos pelo cinto em ambiente domiciliar e 9.66% ± 14.65% para os dados adquiridos pelo cinto em ambiente hospitalar. Embora tenham tido uma maior percenta-gem de artefacto, a razão sinal-ruído dos sinais eletrocardiográficos adquiridos pelo cinto em ambiente domiciliar foi semelhante á dos sinais adquiridos pelos elétrodos de gel em ambiente hospitalar. Resul-tados sugerem uma boa concordância entre os intervalos RR calculados com base nos eletrocardiogra-mas registados em ambientes hospitalar e domiciliar. Além disso, para sinais com percentagem de arte-facto superior a 3%, a avaliação visual dos gráficos de Poincaré provou ser um bom método para a determinação da fonte primária de artefactos (batimentos irregulares ou ruído). A monitorização da aceleração dos sujeitos permitiu o reconhecimento da postura corporal (isto é, deitado ou sentado/em pé) com uma exatidão de 91% e valor preditivo positivo de 80%. Por fim, a classificação da intensidade da atividade física baseado na aceleração inercial e frequências cardíaca e respiratória revelou elevada exatidão, mostrando o potencial desta técnica. Conclusão: O cinto desenvolvido pela Empa provou ser apropriado para monitorização de longa-dura-ção de variáveis físicas e fisiológicos, de uma forma remota e contínua. O cinto permite não só monito-rizar eletrocardiograma, mas também frequência respiratória, postura corporal e intensidade da atividade física. Outros estudos devem ser conduzidos para corroborar os resultados e conclusões deste trabalho. Outros sensores poderão ser integrados no cinto de modo a possibilitar a monitorização de outras vari-áveis fisiológicas de relevância clínica. Este sistema tem o potencial de ser usado como uma ferramenta para predição de doenças e apoio ao diagnóstico

Wearable technology: role in respiratory health and disease

In the future, diagnostic devices will be able to monitor a patient's physiological or biochemical parameters continuously, under natural physiological conditions and in any environment through wearable biomedical sensors. Together with apps that capture and interpret data, and integrated enterprise and cloud data repositories, the networks of wearable devices and body area networks will constitute the healthcare's Internet of Things. In this review, four main areas of interest for respiratory healthcare are described: pulse oximetry, pulmonary ventilation, activity tracking and air quality assessment. Although several issues still need to be solved, smart wearable technologies will provide unique opportunities for the future or personalised respiratory medicine

Analysis of Consistency of Transthoracic Bioimpedance Measurements Acquired with Dry Carbon Black PDMS Electrodes, Adhesive Electrodes, and Wet Textile Electrodes

The detection of intrathoracic volume retention could be crucial to the early detection of decompensated heart failure (HF). Transthoracic Bioimpedance (TBI) measurement is an indirect, promising approach to assessing intrathoracic fluid volume. Gel-based adhesive electrodes can produce skin irritation, as the patient needs to place them daily in the same spots. Textile electrodes can reduce skin irritation; however, they inconveniently require wetting before each use and provide poor adherence to the skin. Previously, we developed waterproof reusable dry carbon black polydimethylsiloxane (CB/PDMS) electrodes that exhibited a good response to motion artifacts. We examined whether these CB/PDMS electrodes were suitable sensing components to be embedded into a monitoring vest for measuring TBI and the electrocardiogram (ECG). We recruited N = 20 subjects to collect TBI and ECG data. The TBI parameters were different between the various types of electrodes. Inter-subject variability for copper-mesh CB/PDMS electrodes and Ag/AgCl electrodes was lower compared to textile electrodes, and the intra-subject variability was similar between the copper-mesh CB/PDMS and Ag/AgCl. We concluded that the copper mesh CB/PDMS (CM/CB/PDMS) electrodes are a suitable alternative for textile electrodes for TBI measurements, but with the benefit of better skin adherence and without the requirement of wetting the electrodes, which can often be forgotten by the stressed HF subjects

Detecting Vital Signs with Wearable Wireless Sensors

The emergence of wireless technologies and advancements in on-body sensor design can enable change in the conventional health-care system, replacing it with wearable health-care systems, centred on the individual. Wearable monitoring systems can provide continuous physiological data, as well as better information regarding the general health of individuals. Thus, such vital-sign monitoring systems will reduce health-care costs by disease prevention and enhance the quality of life with disease management. In this paper, recent progress in non-invasive monitoring technologies for chronic disease management is reviewed. In particular, devices and techniques for monitoring blood pressure, blood glucose levels, cardiac activity and respiratory activity are discussed; in addition, on-body propagation issues for multiple sensors are presented

Wearable sensors for respiration monitoring: a review

This paper provides an overview of flexible and wearable respiration sensors with emphasis on their significance in healthcare applications. The paper classifies these sensors based on their operating frequency distinguishing between high-frequency sensors, which operate above 10 MHz, and low-frequency sensors, which operate below this level. The operating principles of breathing sensors as well as the materials and fabrication techniques employed in their design are addressed. The existing research highlights the need for robust and flexible materials to enable the development of reliable and comfortable sensors. Finally, the paper presents potential research directions and proposes research challenges in the field of flexible and wearable respiration sensors. By identifying emerging trends and gaps in knowledge, this review can encourage further advancements and innovation in the rapidly evolving domain of flexible and wearable sensors.This work was supported by the Spanish Government (MICINN) under Projects TED2021-131209B-I00 and PID2021-124288OB-I00.Peer ReviewedPostprint (published version