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Undersökning av lämpligt tryck att tillämpa i medicinska sensoriska plagg : Vilket tryck mot huden krävs för tillförlitliga signaler från textila sensorerLacson, Carmina, Johansson, Alice January 2021 (has links)
För att kunna underlätta för sjukvården, både med avseende att belastning och för att underlätta för patienter med allergier mot t.ex. limmet som används för att fästa elektroder mot kroppen, arbetas det med att ta fram sensoriska plagg. Ett sensoriskt plagg kan användas för att kontrollera olika mätvärden i vardagen så som hjärtsignaler eller liknande och ska vara lätt för patienten att använda själv hemma. Eller som ett alternativ för någon som är allergisk mot det lim som vanligtvis används för att fästa sensorer mot kroppen. För att sensorerna i plagget ska kunna ge tydliga och användbara mätningar behöver de sitta stilla med ett jämt tryck på sensorerna mot kroppen. För att användaren av det sensoriska plagget ska vilja använda plagget och finna det bekvämt kan inte trycket mot kroppen vara för högt. Därför är det viktigt att ta reda på vilket tryck som uppfattas som bekvämt och vara funktionellt, men också är tillräckligt högt för att få en tydlig och användbar mätning. I denna rapport undersöks därför vilket tryck som uppfattas som gångbart ur användarsynpunkt. Undersökningen genomfördes med hjälp av elva deltagare som testat olika tryck och hur dessa tryck förändras under rörelse. Detta för att hitta vilket tryck deltagarna uppfattade som användbart och tillräckligt bekvämt för att använda i vardagen. Denna undersökning visa stora skillnader på vilket tryck som uppfattas som bekvämt och hur mycket trycket förändras under rörelse. Samt att statisk position inte påverkar signalerna från hjärtat anmärkningsvärt vid de undersökta trycken. / To relieve and ease a small part of the healthcare from work overload and help patients with allergies to glue used to attach the standard sensors, a sensor-equipped wearable garment could be used. The wearable garment could be used to monitor a patient´s values during the day and should be easy for the patient to use themselves at home and comfortable to use every day, or for a patient who is allergic to the glue usually used to attach the sensors. To make the sensors on the sensor-equipped garment work the sensors must sit with pressure against the body to get readable and useful measurement. The pressure from the sensors around the body can not be too tight if it gets too uncomfortable. Therefore it is important to find what pressure that is comfortable enough for the patient to use everyday but still get good enough readings from the measuring devise to be used to monitor the patient´s values. This study looks into what pressure that the participants perceive as comfortable to use on an everyday basis. In this study the pressure is measured on eleven different participants, the pressure was measured at different times and when the participants performed different movements too document the changes in the pressure at movement to find what pressure the participants perceive as comfortable enough for everyday use. This study shows that the pressure perceived as comfortable varies between participants and that the pressure change during movement. It also shows that static position do not affect the quality of the signals from the heart at the used pressures.
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Multiscale Modeling and Analysis of X-ray Windows, Microcantilevers, and Bioimpedance MicroelectrodesLarsen, Kyle Grant 09 August 2022 (has links)
X-ray detector windows must be thin enough to transmit sufficient low-energy x-rays, yet strong enough to withstand up to an atmosphere of differential pressure. Traditional low-energy x-ray windows consist of a support layer and pressure membrane spanning that support. Numerical modeling of several x-ray windows was used to show that both low- and high-energy x-ray transmission can be improved by adding a secondary support structure. Finite element analysis of the x-ray window models showed that the stress from a typical applied load does not exceed the ultimate strength or yield strength of the respective materials. The specific x-ray window models developed in this work may serve as a foundation for improving commercial windows, especially those geared toward low-energy transmission. For local mechanical film testing, microcantilevers were cut in suspended many-layer graphene using a focused ion beam. Multipoint force-deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers. These data were used to estimate the elastic modulus of the film by fitting the compliance at multiple locations along the cantilever to a fixed-free Euler-Bernoulli beam model. This method resulted in a lower uncertainty than is possible from analyzing only a single force-deflection. The breaking strength of the film was also found by deflecting cantilevers until fracture. The average modulus and strength of the many-layer graphene films are 300 GPa and 12 GPa, respectively. The multipoint force-deflection method is well suited to analyze films that are heterogeneous in thickness or wrinkled. Bioimpedance can be measured by applying a known current to the tissue through two (current carrying) electrodes and recording the resulting voltage on two different (pickup) electrodes. Bioimpedance has been used to detect heart rate, respiration rate, blood pressure, and blood glucose. A wrist-based wearable bioimpedance device can measure heart rate by detecting the minute impedance changes caused by the modulation of blood volume in the radial artery. Using finite element analysis, I modeled how electrode position affects sensitivity to pulsatile changes. The highest sensitivity was found to occur when the pickup electrodes were centered over the artery. In this work, we used microfabricated carbon infiltrated-carbon nanotube electrodes to measure the change in contact bioimpedance for dry electrodes, and identical electrodes with a wet electrolyte, on five human subjects in the range of 1 kHz to 100 kHz. We found that the acclimated skin-electrode impedance of the dry electrodes approached that of the wet electrodes, especially for electrodes with larger areas. We also found that the acclimation time does not appear to depend on electrode area or frequency. The skin-electrode impedance after acclimation does depend on electrode area and frequency, decreasing with both. This work shows that if care is taken during the acclimation period, then dry carbon composite electrodes can be used in bioimpedance wearable applications.
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