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- Ahmad, Jawad, 1985-, et al.
(författare)
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A Proposal of Implementation of Sitting Posture Monitoring System for Wheelchair Utilizing Machine Learning Methods
- 2021
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a posture recognition system aimed at detecting sitting postures of a wheelchair user. The main goals of the proposed system are to identify and inform irregular and improper posture to prevent sitting-related health issues such as pressure ulcers, with the potential that it could also be used for individuals without mobility issues. In the proposed monitoring system, an array of 16 screen printed pressure sensor units was employed to obtain pressure data, which are sampled and processed in real-time using read-out electronics. The posture recognition was performed for four sitting positions: right-, left-, forward- and backward leaning based on k-nearest neighbors (k-NN), support vector machines (SVM), random forest (RF), decision tree (DT) and LightGBM machine learning algorithms. As a result, a posture classification accuracy of up to 99.03 percent can be achieved. Experimental studies illustrate that the system can provide real-time pressure distribution value in the form of a pressure map on a standard PC and also on a raspberry pi system equipped with a touchscreen monitor. The stored pressure distribution data can later be shared with healthcare professionals so that abnormalities in sitting patterns can be identified by employing a post-processing unit. The proposed system could be used for risk assessments related to pressure ulcers. It may be served as a benchmark by recording and identifying individuals’ sitting patterns and the possibility of being realized as a lightweight portable health monitoring device.
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| 4. |
- Ahmad, Jawad, 1985-, et al.
(författare)
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Stretchable Pressure Sensor Using Thermoplastic Polyurethane and Conductive Inks
- 2021
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Ingår i: Proceedings of IEEE Sensors. - : IEEE. - 9781728195018
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Konferensbidrag (refereegranskat)abstract
- The development of wearable health devices is an emerging technology, and pressure sensors have been widely used in several of these applications. Plenty of research within pressure sensors is focused on tactile sensing and artificial skin. In this paper, a highly flexible and stretchable pressure sensor is presented. The sensor comprises stretchable thermoplastic polyurethane (TPU) film as substrate and stretchable conductive inks as electrodes and sensing material. Screen printing is used to fabricate electrodes and pressure sensing components on TPU sheets. Electrical and mechanical properties of the fabricated sensors indicate good mechanical and electrical stability while retaining pressure sensing properties and marginal deterioration even after 100 elongation cycles. The findings show that the presented stretchable pressure sensor has a great potential for usage on surfaces where bending and stretching will occur while retaining nearly all of its electrical and mechanical capabilities. The proposed sensor may be employed as a wearable device to detect human movements.
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| 5. |
- Brugés Martelo, Javier Mauricio, et al.
(författare)
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Surface topography characterization of high-quality PE coated paperboard using confocal chromatic microscope and 3D SEM stereo-photogrammetry technique
- 2017
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Konferensbidrag (refereegranskat)abstract
- Coating paperboard enhances printability and optical quality of the product as well as other important properties like packaging performance and shelf-life. To obtain high quality products a quality control of the manufacturing process requires identifying those manufacturing parameters that affect it. Roughness measurement and characterization of coating thickness are examples of these control parameters. Optical instruments measuring these quantities range from laboratory equipment to in-line and on-line sensors. However, the variety of instruments and sometimes misunderstanding of their limitations generate uncorrelated measurements, which are no longer valid to their comparison. The new ISO 25178 standard for surface texture provides guidelines to metrologists to address some this problem. Here, we report a case study for surface characterization of high quality printing polyethylene (PE) coated paperboard for high quality printing, where surface roughness is a key parameter. Two imaging methods to create topographic measurements will be compared, i.e. a confocal chromatic microscope and a scanning electron microscope (SEM). For the latter, stereo photogrammetry is used and 3D topographic profiles are obtained from Alicona MeX software. Leach and Haitjema [Leach, R., & Haitjema, H. (2010). Bandwidth characteristics and comparisons of surface texture measuring instruments. Measurement Science and Technology, 21(3), 032001] addressed the topic on how to design comparisons when using different instruments for areal texture measurement. We use their bandwidth matching concept, since it provides an extension to the ISO 25178 guidelines, ensuring that the instrumentation used to characterize the samples are within its measuring limits and further analysis of the results can be correlated. It is important to adopt a good metrology practice in order to translate these parameters into our future work. We expect to extend these findings into a real-time optical sensor, which later can be implemented in an industrial manufacturing environment for high optical quality paper and paperboard.
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| 6. |
- Li, Xiaotian, et al.
(författare)
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Enabling paper-based flexible circuits with aluminium and copper conductors
- 2019
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Ingår i: IOP Flexible and Printed Electronics. - Temple Way, Bristol BS1 6HG, United Kingdom : IOP Publishing. - 2058-8585. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Implementing electronics systems on paper is an important area of flexible circuit technologies. One of the approaches is to print conductive inks onto paper substrates, on which silicon-based surface mount device components are mounted. However, one of the problems is that the printed conductors have unneglectable resistivity. In this paper, we present paper-based flexible circuits, using copper and aluminium conductors that are laminated onto paper substrates using a high-speed roll-to-roll method. Edge roughness inspections and repeated two-point bending tests are carried out to evaluate the manufactured flexible circuits. Three surface mount techniques are used to assemble standard surface mount device components onto the flexible circuits, including an isotropic conductive adhesive, an anisotropic conductive adhesive, and a low-temperature solder paste. Several characterizations are performed to the surface mount techniques, including contact resistance measurements, component bonding strength tests, assembled circuit bending tests, and scanning electron microscopy. The results of the characterizations suggest that flexible circuits made from Cu with paper substrate achieve satisfactory results for mechanical reliability, all surface mount techniques, and have the potential to be used on automatic component assembly lines. In order to test whether such flexible circuits and surface mount techniques can be used in implementing electronics systems, passive NFC tags with relative humidity sensing functionality are made, which are interrogated by an NFC equipped mobile phone.
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| 7. |
- Li, Xiaotian, et al.
(författare)
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Flexible Circuits Based on Aluminum Conductor and Nonwoven Substrate
- 2019
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Ingår i: 2019 IEEE International Flexible Electronics Technology Conference, IFETC 2019. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728117782
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Konferensbidrag (refereegranskat)abstract
- Electronic textiles, integrating functional electronics circuits into fabric materials, are emerging as an important branch of flexible circuits. In this paper, we introduce a novel material combination for electronic textiles that can be used in implementing hybrid electronics. This type of circuits is fabricated by laminating patterned aluminum foils onto a nonwoven substrate in a high-speed roll-to-roll method. An isotropic conductive adhesive and an anisotropic conductive adhesive are used to assemble standard surface mount device components onto the fabricated circuits. The surface mount techniques are characterized by means of contact resistance measurements, component bonding strength tests, circuit bending tests, and scanning electron microscopy. An NFC tag with relative humidity sensing functionality is fabricated to evaluate the fabricated circuits to an electronic system level.
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| 9. |
- Li, Xiaotian
(författare)
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Towards Large-Area Electronic Systems Using Non-Conventional Substrate and Conductor Materials
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Flexible circuits, also known as flexible printed circuit boards, were originally developed in the 1950s for interconnection between multiple electronic devices when flexibility and movement were required. Nowadays, flexible circuits can be used for implementing electronic systems much more complicated than just interconnections. A commonly seen material combination of flexible circuits is copper foils laminated on polyimide substrates, although these solutions are both expensive and environmentally hazardous. With developments in printed electronics, many non-conventional materials can be used in fabricating flexible circuits that have advantages such as increased flexibility, low cost, a small environmental impact, etc. In addition, fast and efficient manufacturing methods can produce flexible electronics in large volumes. This opens a window of opportunity to create electronic systems over geometrically large areas. This thesis proposes methods and guidelines for how to implement largearea electronic devices using non-conventional flexible materials and technologies. The thesis specifically focuses on electronic systems that integrate both digital and analogue signals. Further, it demonstrates and provides examples of how signals in the microwave frequencies, commonly requiring expensive materials, can be handled with non-conventional materials and technologies. Several conductor-substrate material combinations are used, which are fabricated using industrial processes. The conductor materials include conductive inks, copper foils, and aluminium foils, while the substrate materials comprise papers, a nonwoven fabric, and a polyimide. In particular, methods are investigated in order to achieve a low DC resistance in printed conductiveink-based tracks, which opens the possibilities for them to be used in highcurrent applications. Several surface mounting techniques are developed for incorporating surface mount devices within the fabricated flexible circuits, including the use of low-temperature solder paste, isotropic conductive adhesives, and anisotropic conductive adhesives. Some of the techniques have achieved sufficiently low contact resistance and adequate component bonding strengths, and thus can be used in implementing hybrid electronic systems. In addition, most of the techniques have the potential to be used in automated component assembly lines. As demonstrators, two antenna systems for commercial RFID readers operating at high frequency (13.56 MHz) and ultra-high frequency (867 MHz) iv Abstract bands are implemented, which comprise both digital and analogue signals. The two antenna systems are designed as part of SP4T switching networks using standard antenna elements as the loads of the network. It is shown in the results that both antenna systems have low RF attenuations, the potential to perform passive RFID tag positioning, and the possibility to be expanded to larger areas. Based on the characterisations to the two antenna systems, discussions are made about how large the antenna system areas can be as well as how many antenna elements can be achieved in a single antenna system. This thesis provides a material-to-system approach and demonstrates that non-conventional flexible materials and printed electronic technologies are suitable choices for large-area electronics.
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| 10. |
- Andersson, Anneli, 1992-
(författare)
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How is ADHD associated with comorbidities and health related outcomes? : The role of familial factors and ADHD during pregnancy
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Attention-Deficit/Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder characterized by impaired attention and hyperactivity/impulsivity. ADHD is associated with several comorbidities and health-related outcomes. However, it is uncertain whether ADHD is more strongly associated with certain disorder domains, and whether ADHD-related comorbidities and health-related outcomes is important to consider during pregnancy. Aims: To expand the knowledge regarding the genetic overlap between ADHD and other psychiatric disorder symptoms, and to increase the awareness and understanding related to ADHD in women, with a focus on adverse health behaviors, mental health problems, and pregnancy outcomes. Methods: The present thesis includes one systematic review and metaanalysis (Study I), and three studies based on population-based register data from Sweden (Study II, III, and IV), and Norway (Study II).Results: Individuals with ADHD have an increased liability to meet criteria for externalizing, internalizing and neurodevelopmental disordersymptoms, and these co-occurrences are partly due to shared genetic risks. Further, ADHD is an important risk factor to consider before, during and after pregnancy, as ADHD increases the risk of smoking during pregnancy, mental health problems postpartum, and adverse pregnancy outcomes.Conclusions: The genetic overlaps between ADHD and other psychiatric disorder symptoms were similar across disorder dimensions. Further, results demonstrated that ADHD is an important risk factor to consider in women surrounding pregnancy. These findings point towards the importance of recognizing that women diagnosed with ADHD need to be prioritized and allowed more attention and support by the healthcare system, specifically during their fertile years.
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