7 research outputs found

    Characterization of Polydimethylsiloxane Dielectric Films for Capacitive ECG Bioelectrodes

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    Capacitive ECG bioelectrodes are potentials for wearable and long-term physiological monitoring applications. In non-contact ECG recordings, the dielectric material sets limit to smooth bioelectric signal acquisition. Previously used dielectrics are rigid, unconformable on the skin, induce artefact and triboelectric noise, and becomes unstable when they absorb skin exudates. Recently, polymeric materials such as PDMS have gained different biomedical applications because it is biocompatible, flexible, and easy to fabricate. However, its use as a dielectric for capacitive ECG sensing is poorly reported. In this study, 15 samples of thin PDMS films of various thicknesses were fabricated by varying the proportion of the Sylgard 184TM silicone elastomer to the crosslinker from Dow Corning Corporation and manually deposited on acrylic glass substrates. The composition ratio and thickness were used to tune the structure and dielectric properties of the films. The effects on the capacitance generated by each dielectric film were measured using the parallel plate method, and their corresponding values of relative permittivity was also estimated. The results obtained reveal that PDMS films made from a composition ratio of 10:2 yielded the maximum capacitance and relative permittivity. In contrast, the film with 0.14mm thickness revealed the highest value of capacitance (31pF). The recorded values of capacitance demonstrate the feasibility of PDMS dielectrics for capacitive ECG bioelectrodes

    A Hybrid-Powered Wireless System for Multiple Biopotential Monitoring

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    Chronic diseases are the top cause of human death in the United States and worldwide. A huge amount of healthcare costs is spent on chronic diseases every year. The high medical cost on these chronic diseases facilitates the transformation from in-hospital to out-of-hospital healthcare. The out-of-hospital scenarios require comfortability and mobility along with quality healthcare. Wearable electronics for well-being management provide good solutions for out-of-hospital healthcare. Long-term health monitoring is a practical and effective way in healthcare to prevent and diagnose chronic diseases. Wearable devices for long-term biopotential monitoring are impressive trends for out-of-hospital health monitoring. The biopotential signals in long-term monitoring provide essential information for various human physiological conditions and are usually used for chronic diseases diagnosis. This study aims to develop a hybrid-powered wireless wearable system for long-term monitoring of multiple biopotentials. For the biopotential monitoring, the non-contact electrodes are deployed in the wireless wearable system to provide high-level comfortability and flexibility for daily use. For providing the hybrid power, an alternative mechanism to harvest human motion energy, triboelectric energy harvesting, has been applied along with the battery to supply energy for long-term monitoring. For power management, an SSHI rectifying strategy associated with triboelectric energy harvester design has been proposed to provide a new perspective on designing TEHs by considering their capacitance concurrently. Multiple biopotentials, including ECG, EMG, and EEG, have been monitored to validate the performance of the wireless wearable system. With the investigations and studies in this project, the wearable system for biopotential monitoring will be more practical and can be applied in the real-life scenarios to increase the economic benefits for the health-related wearable devices

    Electrostatic Sensors – Their Principles and Applications

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    Over the past three decades electrostatic sensors have been proposed, developed and utilised for the continuous monitoring and measurement of a range of industrial processes, mechanical systems and clinical environments. Electrostatic sensors enjoy simplicity in structure, cost-effectiveness and suitability for a wide range of installation conditions. They either provide unique solutions to some measurement challenges or offer more cost-effective options to the more established sensors such as those based on acoustic, capacitive, optical and electromagnetic principles. The established or potential applications of electrostatic sensors appear wide ranging, but the underlining sensing principle and resultant system characteristics are very similar. This paper presents a comprehensive review of the electrostatic sensors and sensing systems that have been developed for the measurement and monitoring of a range of process variables and conditions. These include the flow measurement of pneumatically conveyed solids, measurement of particulate emissions, monitoring of fluidised beds, on-line particle sizing, burner flame monitoring, speed and radial vibration measurement of mechanical systems, and condition monitoring of power transmission belts, mechanical wear, and human activities. The fundamental sensing principles together with the advantages and limitations of electrostatic sensors for a given area of applications are also introduced. The technology readiness level for each area of applications is identified and commented. Trends and future development of electrostatic sensors, their signal conditioning electronics, signal processing methods as well as possible new applications are also discussed

    Blind Source Separation for the Processing of Contact-Less Biosignals

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    (Spatio-temporale) Blind Source Separation (BSS) eignet sich für die Verarbeitung von Multikanal-Messungen im Bereich der kontaktlosen Biosignalerfassung. Ziel der BSS ist dabei die Trennung von (z.B. kardialen) Nutzsignalen und Störsignalen typisch für die kontaktlosen Messtechniken. Das Potential der BSS kann praktisch nur ausgeschöpft werden, wenn (1) ein geeignetes BSS-Modell verwendet wird, welches der Komplexität der Multikanal-Messung gerecht wird und (2) die unbestimmte Permutation unter den BSS-Ausgangssignalen gelöst wird, d.h. das Nutzsignal praktisch automatisiert identifiziert werden kann. Die vorliegende Arbeit entwirft ein Framework, mit dessen Hilfe die Effizienz von BSS-Algorithmen im Kontext des kamera-basierten Photoplethysmogramms bewertet werden kann. Empfehlungen zur Auswahl bestimmter Algorithmen im Zusammenhang mit spezifischen Signal-Charakteristiken werden abgeleitet. Außerdem werden im Rahmen der Arbeit Konzepte für die automatisierte Kanalauswahl nach BSS im Bereich der kontaktlosen Messung des Elektrokardiogramms entwickelt und bewertet. Neuartige Algorithmen basierend auf Sparse Coding erwiesen sich dabei als besonders effizient im Vergleich zu Standard-Methoden.(Spatio-temporal) Blind Source Separation (BSS) provides a large potential to process distorted multichannel biosignal measurements in the context of novel contact-less recording techniques for separating distortions from the cardiac signal of interest. This potential can only be practically utilized (1) if a BSS model is applied that matches the complexity of the measurement, i.e. the signal mixture and (2) if permutation indeterminacy is solved among the BSS output components, i.e the component of interest can be practically selected. The present work, first, designs a framework to assess the efficacy of BSS algorithms in the context of the camera-based photoplethysmogram (cbPPG) and characterizes multiple BSS algorithms, accordingly. Algorithm selection recommendations for certain mixture characteristics are derived. Second, the present work develops and evaluates concepts to solve permutation indeterminacy for BSS outputs of contact-less electrocardiogram (ECG) recordings. The novel approach based on sparse coding is shown to outperform the existing concepts of higher order moments and frequency-domain features

    Single-Unit Leadless EEG Sensor

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    Non-convulsive seizure (NCS) and non-convulsive status epilepticus (NCSE) are severe neurological disorders within intensive care units (ICUs) and emergency departments (EDs). Traditionally, physiological monitoring in ICUs and EDs focuses on cardiopulmonary variables, including blood pressure and heart rate. The neurological conditions, on the other hand, are often assessed by bedside observations from physicians. Without proper monitoring tools, the NCS and NCSE that lack observable clinical manifestations are easily overlooked or misdiagnosed. The problem can be amplified among patients with impaired consciousness who cannot respond to environmental stimuli. The delayed detection and treatment lead to substantial morbidity, mortality, and healthcare costs. Currently, electroencephalography (EEG) is the most effective diagnostic tool for NCS and NCSE in ICUs and EDs. Meanwhile, less than two percent of the critically ill patients in ICUs and EDs are undergoing EEG. The under-adoption or decreased utilization of EEG originates from challenges to accommodate EEG into established practice protocols. Therefore, the timely acquisition of EEG has been one of the paramount needs in today’s emergency care. This dissertation presents a novel EEG sensor that is leadless, self-contained, and the size of a U.S. Penny. The sensor enables rapid EEG setup and efficient EEG acquisition. The dissertation first investigated into a novel EEG electrode-structure enclosing four unique arc-shaped electrodes. We demonstrated the feasibility of such electrode configuration by experimental investigations on both a physical model and a healthy human subject. The dissertation then presented Monte Carlo simulations to predict the statistical performance of the single-unit sensor on the whole brain. A forward computation algorithm was implemented to compute the scalp potential in response to dipolar sources within an analytically modeled brain. The data-informed findings indicated that the whole-brain quantitative performance of this electrode configuration is comparable to the cup electrode currently used as the gold standard. The results are presented in a multi-variant probability density function. Taken a step further, a deterministic solution to such probability model was derived. These results provide insights into the workings of the single-unit sensor. Furthermore, a single-unit sensor prototype was constructed with a specially designed electronic system. The performance of the prototype was validated through experiments on a healthy human subject. Lastly, the efficacy of the prototype is demonstrated indirectly using pre-recorded EEG data from epilepsy patients. It has been observed that seizure signal can be detected via a neighboring bipolar recording configuration, which closely simulates the case of single-unit sensors for the detection of NCS and NCSE. The results of series of investigations conclude the feasibility and single-unit sensors in detecting epileptic EEG signals

    Vital Sign Monitoring in Automotive Environments

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    Diplomová práce je věnována problematice monitorování vitálních funkcí v automobilním prostředí. Teoretická část je popsána formou ucelené rešerše, která shrnuje aktuálně dostupné monitorovací metody pro neinvazivní snímání životně důležitých parametrů v automobilním zařízení. Experimentální část práce popisuje návrh a realizaci pneumatického systému, který bude následně integrován do autosedačky nebo bezpečnostního pásu. Součástí praktické části je také návrh a realizace experimentálních měření pro stanovení přesnosti navržených senzorů v reálném prostředí automobilu. Obsah práce je doplněn o testování vlivu typu materiálu, tvaru, velikosti, zapouzdření a umístění senzoru, způsobu zpracování naměřených signálů a různých podmínek jízdy v automobilu. Závěr práce patří statistickému vyhodnocení dosaženích výsledků. Hodnocení využívá srovnání zpracované průměrné variability srdečného tepu extrahovaného z balistokardiografického signálu vůči referenci (elektrokardiografický signál). Kompletní program včetně zpracování dat je zpracován v programovém prostředí Matlab.The scope of this thesis is vital sign monitoring in automotive enviroments. The theoretical part is written in a form of a comprehensive research, which summarizes the currently available monitoring methods for non-invasive sensing of vital parameters in automobiles. The aim of the experimental part is to design and implement a pneumatic system that will be integrated into a car seat or seat belt. Experimental part also includes the design and implementation of experimental measurements that determine the accuracy of the designed sensors in a real car application. The content of this thesis is complemented by testing the impact of the type of material, shape, size, encapsulation and location of the sensors, the type of the processing method and various driving conditions in the car. The conclusion of the thesis is dedicated to the statistical evaluation of the results. The comparison of the reference with the processed average heart rate variability extracted from the ballistocardiography (electrocardiography) is used for the statistical evaluation. The complete program including the data processing is written in Matlab.450 - Katedra kybernetiky a biomedicínského inženýrstvídobř

    E-textile technology review - from materials to application

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    Wearable devices are ideal for personalized electronic applications in several domains such as healthcare, entertainment, sports and military. Although wearable technology is a growing market, current wearable devices are predominantly battery powered accessory devices, whose form factors also preclude them from utilizing the large area of the human body for spatiotemporal sensing or energy harvesting from body movements. E-textiles provide an opportunity to expand on current wearables to enable such applications via the larger surface area offered by garments, but consumer devices have been few and far between because of the inherent challenges in replicating traditional manufacturing technologies (that have enabled these wearable accessories) on textiles. Also, the powering of e-textile devices with battery energy like in wearable accessories, has proven incompatible with textile requirements for flexibility and washing. Although current e-textile research has shown advances in materials, new processing techniques, and one-off e-textile prototype devices, the pathway to industry scale commercialization is still uncertain. This paper reports the progress on the current technologies enabling the fabrication of e-textile devices and their power supplies including textile-based energy harvesters, energy storage mechanisms, and wireless power transfer solutions. It identifies factors that limit the adoption of current reported fabrication processes and devices in the industry for mass-market commercialization
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