Novel Methods for Weak Physiological Parameters Monitoring.

M.S. Thesis. University of Hawaiʻi at Mānoa 2017

Hand-breathe: Non-Contact Monitoring of Breathing Abnormalities from Hand Palm

In post-covid19 world, radio frequency (RF)-based non-contact methods, e.g., software-defined radios (SDR)-based methods have emerged as promising candidates for intelligent remote sensing of human vitals, and could help in containment of contagious viruses like covid19. To this end, this work utilizes the universal software radio peripherals (USRP)-based SDRs along with classical machine learning (ML) methods to design a non-contact method to monitor different breathing abnormalities. Under our proposed method, a subject rests his/her hand on a table in between the transmit and receive antennas, while an orthogonal frequency division multiplexing (OFDM) signal passes through the hand. Subsequently, the receiver extracts the channel frequency response (basically, fine-grained wireless channel state information), and feeds it to various ML algorithms which eventually classify between different breathing abnormalities. Among all classifiers, linear SVM classifier resulted in a maximum accuracy of 88.1\%. To train the ML classifiers in a supervised manner, data was collected by doing real-time experiments on 4 subjects in a lab environment. For label generation purpose, the breathing of the subjects was classified into three classes: normal, fast, and slow breathing. Furthermore, in addition to our proposed method (where only a hand is exposed to RF signals), we also implemented and tested the state-of-the-art method (where full chest is exposed to RF radiation). The performance comparison of the two methods reveals a trade-off, i.e., the accuracy of our proposed method is slightly inferior but our method results in minimal body exposure to RF radiation, compared to the benchmark method

Design and Implementation of a Stepped Frequency Continuous Wave Radar System for Biomedical Applications

There is a need to detect vital signs of human (e.g., the respiration and heart-beat rate) with noncontact method in a number of applications such as search and rescue operation (e.g. earthquakes, fire), health monitoring of the elderly, performance monitoring of athletes Ultra-wideband radar system can be utilized for noncontact vital signs monitoring and tracking of various human activities of more than one subject. Therefore, a stepped-frequency continuous wave radar (SFCW) system with wideband performance is designed and implemented for Vital signs detection and fall events monitoring. The design of the SFCW radar system is firstly developed using off-the-shelf discrete components. Later, the system is implemented using surface mount components to make it portable with low cost. The measurement result is proved to be accurate for both heart rate and respiration rate detection within ±5% when compared with contact measurements. Furthermore, an electromagnetic model has been developed using a multi-layer dielectric model of the human subject to validate the experimental results. The agreement between measured and simulated results is good for distances up to 2 m and at various subjects’ orientations with respect to the radar, even in the presence of more than one subject. The compressive sensing (CS) technique is utilized to reduce the size of the acquired data to levels significantly below the Nyquist threshold. In our demonstration, we use phase information contained in the obtained complex high-resolution range profile (HRRP) to derive the motion characteristics of the human. The obtained data has been successfully utilized for non-contact walk, fall and limping detection and healthcare monitoring. The effectiveness of the proposed method is validated using measured results

Bio-Radar Applications for Remote Vital Signs Monitoring

Nowadays, most vital signs monitoring techniques used in a medical context and/or daily life routines require direct contact with skin, which can become uncomfortable or even impractical to be used regularly. Radar technology has been appointed as one of the most promising contactless tools to overcome these hurdles. However, there is a lack of studies that cover a comprehensive assessment of this technology when applied in real-world environments. This dissertation aims to study radar technology for remote vital signs monitoring, more specifically, in respiratory and heartbeat sensing. Two off-the-shelf radars, based on impulse radio ultra-wideband and frequency modu lated continuous wave technology, were customized to be used in a small proof of concept experiment with 10 healthy participants. Each subject was monitored with both radars at three different distances for two distinct conditions: breathing and voluntary apnea. Signals processing algorithms were developed to detect and estimate respiratory and heartbeat parameters, assessed using qualitative and quantitative methods. Concerning respiration, a minimum error of 1.6% was found when radar respiratory peaks signals were directly compared with their reference, whereas a minimum mean absolute error of 0.3 RPM was obtained for the respiration rate. Concerning heartbeats, their expression in radar signals was not as clear as the respiration ones, however a minimum mean absolute error of 1.8 BPM for heartbeat was achieved after applying a novel selective algorithm developed to validate if heart rate value was estimated with reliability. The results proved the potential for radars to be used in respiratory and heartbeat contactless sensing, showing that the employed methods can be already used in some mo tionless situations. Notwithstanding, further work is required to improve the developed algorithms in order to obtain more robust and accurate systems.Atualmente, a maioria das técnicas usadas para a monitorização de sinais vitais em contexto médicos e/ou diário requer contacto direto com a pele, o que poderá tornar-se incómodo ou até mesmo inviável em certas situações. A tecnologia radar tem vindo a ser apontada como uma das mais promissoras ferramentas para medição de sinais vitais à distância e sem contacto. Todavia, são necessários mais estudos que permitam avaliar esta tecnologia quando aplicada a situações mais reais. Esta dissertação tem como objetivo o estudo da tecnologia radar aplicada no contexto de medição remota de sinais vitais, mais concretamente, na medição de atividade respiratória e cardíaca. Dois aparelhos radar, baseados em tecnologia banda ultra larga por rádio de impulso e em tecnologia de onda continua modulada por frequência, foram configurados e usados numa prova de conceito com 10 participantes. Cada sujeito foi monitorizado com cada um dos radar em duas situações distintas: respirando e em apneia voluntária. Algorit mos de processamento de sinal foram desenvolvidos para detetar e estimar parâmetros respiratórios e cardíacos, avaliados através de métodos qualitativos e quantitativos. Em relação à respiração, o menor erro obtido foi de 1,6% quando os sinais de radar respiratórios foram comparados diretamente com os sinais de referência, enquanto que, um erro médio absoluto mínimo de 0,3 RPM foi obtido para a estimação da frequência respiratória via radar. A expressão cardíaca nos sinais radar não se revelou tão evidente como a respiratória, no entanto, um erro médio absoluto mínimo de 1,8 BPM foi obtido para a estimação da frequência cardíaca após a aplicação de um novo algoritmo seletivo, desenvolvido para validar a confiança dos valores obtidos. Os resultados obtidos provaram o potencial do uso de radares na medição de atividade respiratória e cardíaca sem contacto, sendo esta tecnologia viável de ser implementada em situações onde não existe muito movimento. Não obstante, os algoritmos desenvolvidos devem ser aperfeiçoados no futuro de forma a obter sistemas mais robustos e precisos

Noncontact Vital Signs Detection

Human health condition can be accessed by measurement of vital signs, i.e., respiratory rate (RR), heart rate (HR), blood oxygen level, temperature and blood pressure. Due to drawbacks of contact sensors in measurement, non-contact sensors such as imaging photoplethysmogram (IPPG) and Doppler radar system have been proposed for cardiorespiratory rates detection by researchers.The UWB pulse Doppler radars provide high resolution range-time-frequency information. It is bestowed with advantages of low transmitted power, through-wall capabilities, and high resolution in localization. However, the poor signal to noise ratio (SNR) makes it challenging for UWB radar systems to accurately detect the heartbeat of a subject. To solve the problem, phased-methods have been proposed to extract the phase variations in the reflected pulses modulated by human tiny thorax motions. Advance signal processing method, i.e., state space method, can not only be used to enhance SNR of human vital signs detection, but also enable the micro-Doppler trajectories extraction of walking subject from UWB radar data.Stepped Frequency Continuous Wave (SFCW) radar is an alternative technique useful to remotely monitor human subject activities. Compared with UWB pulse radar, it relieves the stress on requirement of high sampling rate analog-to-digital converter (ADC) and possesses higher signal-to-noise-ratio (SNR) in vital signs detection. However, conventional SFCW radar suffers from long data acquisition time to step over many frequencies. To solve this problem, multi-channel SFCW radar has been proposed to step through different frequency bandwidths simultaneously. Compressed sensing (CS) can further reduce the data acquisition time by randomly stepping through 20% of the original frequency steps.In this work, SFCW system is implemented with low cost, off-the-shelf surface mount components to make the radar sensors portable. Experimental results collected from both pulse and SFCW radar systems have been validated with commercial contact sensors and satisfactory results are shown

Uwb Radar İle Duvar Arkasındaki İnsanın Teneffüsünü Algılama Yöntemlerinin İyileştirilmesi

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Bilişim Enstitüsü, 2013Thesis (M.Sc.) -- İstanbul Technical University, Institute of Informatics, 2013Günümüzde alıcı, verici sistemlerinde iletişimin kaliteli olması için anten tasarımı çok önem taşımaktadır. Antenin bir devrimi sayılan Mikroşerit antenler birçok özelliklere sahip oldukları için kablosuz haberleşme, radar ve uydu haberleşmesinde kullanım alanı bulmuştur. Kolay üretilebilmesi, boyut olarak az yer kaplaması bu özelliklerdendir. Bunların yanı sıra, dar bantlı olması ve yüksek kazanca sahip olmaması bu antenin dezavantajlarındandır. Bu sorunların çözümü olarak, dizi antenler önerilir. Dizi antenler tasarıma bağlı olarak, daha fazla bant genişliğine ve kazanca sahiptirler. Birden fazla antenin yan yana veya farklı kombinasyonlarla bir araya gelmesi birkaç yan etkiye de sebep olacaktır. Antenlerin birbiriyle etkileşimleri ve daha büyük boyuta sahip olmaları, dizilerin dezavantajlarındadır. Tasarım açısından, antenlerin dizilişinin yanısıra, besleme tipleri de önem taşımaktadır. Kaynaktan gelen gücü doğru paylaştırmak ve istenilen zaman ve faz gecikmesini yaratmak besleme şebekesinin görevlerindendir. Dolayısıyla, iyi tasarlanmış besleme şebekesi dizi anteniyle birlikte iyi bir performans doğuracaktır. Dizi antenler yüksek kazanca sahip oldukları için, uydu haberleşmesi, DSB (Direct Broadcasting Service), WLAN (Wireless Local Area Networks) ve uzay haberleşmesi gibi birçok uygulamada kullanılmaktadır. Uydu haberleşmesi, WLAN, DBS, GNSS (Global Navigation Satellite Systems), RFID (Radio Frequency Identification), WPAN (Wireless Personal Area Networks) GNSS, WiMAX (Worldwide Interoperability for Microwave Access) ve kablosuz haberleşme gibi uygulamalarda doğrusal polarizasyon yerine dairesel polarizasyonlu antenler tercih edilir. Bunun sebebi, dairesel polarizasyonunun sağladığı avantajlardır. Bu avantajların birkaç tanesi aşağıdaki gibidir. Alıcı ve verici antenler dairesel polarizasyonlu olduğu takdirde doğrusal polarizasyonlu antenler gibi ilk ayarlara ihtiyaç duymayacaktır. Dairesel polarizasyonlu anten kullanarak polarizasyon uyumsuzluk kayıpları da önlenmiş olur. Dairesel polarizasyonlu antenler kullanarak çok yollu etkileşimler ve kayıplar da önlenebilir. Sağ dairesel polarizasyonlu işaret (Right-Hand Circular Polarization (RHCP)) vericiden gönderiliyorsa, ortamdan alıcıya doğru yansıyan işaret sol polarizasyonlu olduğu için (left-hand circular polarization (LHCP)) girişim önlenecektir. Ayrıca uydu haberleşmesinde karşılaştığımız Faraday rotasyonu kaybını da giderme kabiliyetine sahiptir. Uydu haberleşmesi, mikrodalga radyo haberleşmesi ve radar gibi uygulamalar C bandında çalıştıkları için tasarlamak istediğimiz antenin C bandında olması planlanmaktadır. C bandı IEEE tarafından 4 GHz'den den 8 GHz aralığına kadar tanımlanmıştır. Bu bantta çalışmanın avantajları, birçok alana uygun olmasıdır. Örneğin hava tahmini uydularında Ku bandı yerine C bandı kullandığımız da yağmur zayıflatması (Rain Fade) denilen kayıpları oldukça azaltabiliriz. Bu çalışmada C bandı için uygun dairesel polarizasyonlu dizi antenler tasarlanıp performansını artırmak için yöntemler sunulacaktır. Tasarım esnasında ilk olarak, dizi antenin bant genişliği ve kazancı üzerinde çalışılacaktır. Bunun için önce dairesel anten elamanının tasarım metotları tartışılıp performansı artırılacaktır. Uygun bir anten tasarlandıktan sonra, antenin dizilişi ve besleme şebekesi üzerinde çalışılıp Butler matrisi gibi yeni besleme şebekeleri sunulacaktır. Bu amaçlara ulaşma yolunda, izlnilenecek adımlar aşağıdaki gibidir. CPSSA tasarımının 3 dB axial-ratio, 2 GHz e kadar yükseltilmiştir. CPSSA 3 le 11.1 GHz aralığında çalışacak şekilde tasarlanıp empedans bant genişliği 115 % e ulaşmıştır. Simülasyon ve gerçek model sonuçları yeterince uyumlu olduğu tespit edilmiştir (2.1 bölüm). 2.2. bölümdeyse, anten elemanının boyutu 20×20 mm2 olarak tasarlanmıştır. Bu anten için ölçülen empedans bant genişliği 11050 MHz (2950–14000 MHz) 3-dB AR iğse 3373 MHz (35.7%) 3729 den 7102 MHz ve ortalama kazanç 3.5 dBi elde edilmiştir. 2.3 ve 2.4 bölümlerinde dizi antenler için yeni besleme şebekeleri tasarlanmıştır. 2.3 de olan dizi antenin 3 dB axial-ratio bant genişliği 1.3 GHz e ulaşmıştır. 2.4 te ise, dizi antenin besleme şebekesi geliştirilmiştir. 2×2 dizi anteninin empedans bant genişliği 78.5% ve 3dB axial-ratio bant genişliği 35.7% e ulaşmıştır. Ortalama 14.2 dBic kazanç sağlanmıştır. Son bölümlerde (2.5 – 2.7) geniş bantlı performans almak üzere, iki yeni dizi anten tasarlanmıştır. Bu yapılar, polarizasyon çevir me özelliklerine de sahiptir. 2.5 de bu özellik bir Vivaldi anteni kullanarak sağlanmıştır. 2.6. bölümle özgün Butler matrisiyle dizi anten tasrlanmıştır.Çalışmaların tüm detayları ve sonuçları sunulacaktır.The C band is a name given to certain portions of the electromagnetic spectrum, including wavelengths of microwaves that are used for long-distance radio telecommunications. The IEEE C-band (4 to 8 GHz) and its slight variations contain frequency ranges that are used for many satellite communications transmissions, some Wi-Fi devices, some cordless telephones, and some weather radar systems. For satellite communications, the microwave frequencies of the C-band perform better under adverse weather conditions in comparison with the Ku band (11.2 GHz to 14.5 GHz) microwave frequencies used by other communication satellites. The increasing demands for more capacity and higher data rate in wireless systems have led to the development of broadband CP antennas. During recent decades, a variety of broadband CP antennas have been proposed for applications in mobile satellite communications, WLAN, DBS, RFID, GNSS, space communications and wireless power transmission systems. The CP antenna is very effective in combating multi-path interferences or fading . The reflected radio signal from the ground or other objects will result in a reversal of polarization, that is, right-hand circular polarization (RHCP) reflections show left-hand circular polarization (LHCP). A RHCP antenna will have a rejection of a reflected signal which is LHCP, thus reducing the multi-path interferences from the reflected signals. The second advantage is that CP antenna is able to reduce the 'Faraday rotation' effect due to the ionosphere. The Faraday rotation effect causes a significant signal loss (about 3 dB or more) if linearly polarized signals are employed. The CP antenna is immune to this problem, thus the CP antenna is widely used for space telemetry applications of satellites, space probes and ballistic missiles to transmit or receive signals that have undergone Faraday rotation by travelling through the ionosphere. Another advantage of using CP antennas is that no strict orientation between transmitting and receiving antennas is required. This is different from linearly polarized antennas which are subject to polarization mismatch losses if arbitrary polarization misalignment occurs between transmitting and receiving antennas. This is useful for mobile satellite communications where it is difficult to maintain a constant antenna orientation. With CP, the strength of the received signals is fairly constant regardless of the antenna orientation. These advantages make CP antennas very attractive for many wireless systems. For a circularly polarized microstrip antenna, both axial ratio and impedance bandwidths need considerations. Use the array antenna is a recognized methods to increase axial ratio bandwidth and gain of circularly polarized antenna. for better result in increase the impedance bandwidth and decrease the array mutual coupling prepare feed network have to design too. In this thesis, with attention to advantage of CP antenna and C-band application as mentioned above, will be tried to generate a CP array antenna by broadband feed network and antenna element. In order to achieve mentioned CP array antenna, three aspects will be considered. In first step (aspect 1), will be focused on feed network. For this purpose, will be employed broadband microwave components such as broadband power divider, broadband hybrid coupler and broadband phase shifter instead of equal narrowband component that hitherto, have been utilized. Use of broadband CP antenna element with high gain will be the second priority. To achieve broadband CP element, use of slot antenna and in order to attain high gain element, use of cavity back structure are recommended. In this case, the single element must be changed polarization diversity because the feed network will be able to change polarization diversity and for this purpose, polarization of element and feed network should be coordinated. In third step (aspect 3), method of location element in array such as distance between element, mutual coupling between them and feed network will be significant. Also, communicate between feeding in array feed network and antenna elements, in order to impedance matching and power transfer, have important role. Thus, In order to achieve the above mentioned goals antennas were created as follows:a 3 dB axial-ratio of the CPSSA extends to approximately 2 GHz. The CPSSA was designed to operate over the frequency range between 3 and 11.1 GHz corresponding to an impedance bandwidth of 115% for VSWR<2. Acceptable agreement between the simulation and measured results validates the proposed design (section 2.1). And then a compact size of 20×20 mm2 CPSSA in section 2.2 is reported. The measured impedance bandwidth is as large as 11050 MHz (2950–14000 MHz) or about 130.38% with respect to the center frequency. The measured 3-dB AR is 3373 MHz (35.7%) from 3729 to 7102 MHz and the average measured gain of CPSSA is almost 3.5 dBi in the operating band.In oder to attain array antenna by broadband CP antenna elements in section 2.3 and 2.4 two type of antenna with novel methodes in designing feed network are reported. In first case a array antenna which feed by sequentially rotated feed network is mentioned. the 3 dB axial-ratio bandwidth of the this array antenna extends to approximately 1.3 GHz and was designed to operate over the frequency range between 4.5 and 6.4 GHz corresponding to an impedance bandwidth of 34.86% for VSWR<2 (section 2.3). in section 2.4 by modified feed network and array elements the characteristics of array was improved. The reported array consists of 2×2 CPSSA elements and is fed by a novel feeding network consisting of the circuit strip-line couplers and delay lines. The feeding technique is applied to the 2×2 antenna array to increasing the axial ratio (AR) bandwidth. The measured impedance bandwidth for VSWR < 2 is around 78.5% (3.4 – 7.8 GHz) and 3dB axial-ratio bandwidth is about 35.7% (4.6–6.6 GHz) and average 14.2 dBic gain over the 3 dB ARBW. In final, in order to investigate of broadband feeding network and elements on array antenna, two type of array with capable to change polarization and pattern diversity are reported (sections 2.5-2.7). for example in sectin 2.5, a array antenna by changing to polarization diversity by broadband vivaldi antenna is reported and in section 2.6, a beam steering array antenna composed of a broadband circularly polarized square slot antenna and a novel Butler matrix feed network designed with a broadband branch line coupler is introduced. The Results show that a compact and its improvements are discussed. In this work a broadband double box coupler with impedance bandwidth over 5 - 7.4 GHz frequency and the phase error less than 3 degree is employed. Also the measured impedance bandwidth of the proposed beam steering array antenna is 39% (from 4.7GHz to 7 GHz). The minimum 3dB axial ratio (AR) bandwidth between ports, support 4.55 - 6.7 GHz frequency range. The measured peak gain of proposed array antenna is 10.1 dBic that could scan solid angle approximately 25 steradian.Yüksek LisansM.Sc

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 145

This bibliography lists 301 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1975

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 127, April 1974

This special bibliography lists 279 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1974

Antennas And Wave Propagation In Wireless Body Area Networks: Design And Evaluation Techniques

Recently, fabrication of miniature electronic devices that can be used for wireless connectivity becomes of great interest in many applications. This has resulted in many small and compact wireless devices that are either implantable or wearable. As these devices are small, the space for the antenna is limited. An antenna is the part of the wireless device that receives and transmits a wireless signal. Implantable and wearable antennas are very susceptible to harmful performance degradation caused by the human body and very difficult to integrate, if not designed properly. A designer need to minimize unwanted radiation absorption by the human body to avoid potential health issues. Moreover, a wearable antenna will be inevitably exposed to user movements and has to deal with influences such as crumpling and bending. These deformations can cause degraded performance or a shifted frequency response, which might render the antenna less effective. The existing wearable and implantable antennas’ topologies and designs under discussion still suffer from many challenges such as unstable antenna behavior, low bandwidth, considerable power generation, less biocompatibility, and comparatively bigger size. The work presented in this thesis focused on two main aspects. Part one of the work presents the design, realization, and performance evaluation of two wearable antennas based on flexible and textile materials. In order to achieve high body-antenna isolation, hence, minimal coupling between human body and antenna and to achieve performance enhancement artificial magnetic conductor is integrated with the antenna. The proposed wearable antennas feature a small footprint and low profile characteristics and achieved a wider -10 dB input impedance bandwidth compared to wearable antennas reported in literature. In addition, using new materials in wearable antenna design such as flexible magneto-dielectric and dielectric/magnetic layered substrates is investigated. Effectiveness of using such materials revealed to achieve further improvements in antenna radiation characteristics and bandwidth and to stabilize antenna performance under bending and on body conditions compared to artificial magnetic conductor based antenna. The design of a wideband biocompatible implantable antenna is presented. The antenna features small size (i.e., the antenna size in planar form is 2.52 mm3), wide -10 dB input impedance bandwidth of 7.31 GHz, and low coupling to human tissues. In part two, an overview of investigations done for two wireless body area network applications is presented. The applications are: (a) respiratory rate measurement using ultra-wide band radar system and (b) an accurate phase-based localization method of radio frequency identification tag. The ultimate goal is to study how the antenna design can affect the overall system performance and define its limitations and capabilities. In the first studied application, results indicate that the proposed sensing system is less affected and shows less error when an antenna with directive radiation pattern, low cross-polarization, and stable phase center is used. In the second studied application, results indicate that effects of mutual coupling between the array elements on the phase values are negligible. Thus, the phase of the reflected waves from the tag is mainly determined by the distance between the tag and each antenna element, and is not affected by the induced currents on the other elements