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  • 1. Guo, Li
    et al.
    Berglin, Lena
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Mattila, Heikki
    Design of a garment-based sensing system for breathing monitoring2013Inngår i: Textile research journal, ISSN 0040-5175, E-ISSN 1746-7748, Vol. 83, nr 5, s. 499-509Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The long-term monitoring of biophysiological signals requires new types of sensor systems that are wearable and at the same time convenient for the users. This paper describes the design of a novel garment-based sensing system for the long-term monitoring of breathing rhythm. The system concept was realized in a prototype garment, integrated with coated piezoresistive sensors. The prototype garment was tested by five subjects, and compared with a standard piezoelectric respiratory belt. Each signal was quantitatively and qualitatively evaluated in the time and frequency domain to make sure that no medical and diagnostic information was lost. The results showed a good agreement between the garment-based sensors and the standard reference, where errors occurred only when the breathing rate was extremely high. The garment-based sensor system could also distinguish the predominance breathing compartment (chest versus abdominal breathing). The system could detect a 10 s pause in breathing, which could be of importance in studies of sleep apnea. A garment-based sensing system maintains the accuracy of the signal quality without reducing the comfort for the user. It makes possible long-term ambulatory monitoring and has home-based healthcare applications.

  • 2.
    Lanz, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sandström, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB, Tvistevägen 47, PO Box 7970, SE-90719 Umeå, Sweden.
    Tang, Shi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB, Tvistevägen 47, PO Box 7970, SE-90719 Umeå, Sweden.
    Chabrecek, Peter
    Sefar AG.
    Sonderegger, Uriel
    Sefar AG.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB, Tvistevägen 47, PO Box 7970, SE-90719 Umeå, Sweden.
    A light–emission textile device: conformal spray-sintering of a woven fabric electrode2016Inngår i: Flexible and Printed Electronics, ISSN 2058-8585, Vol. 1, nr 2, artikkel-id 025004Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on the realization of an ultra-flexible, light-weight and large-area emissive textile device. The anode and active material of a light-emitting electrochemical cell (LEC) were deposited by conformal spray-coating of a transparent fabric-based electrode, comprising a weave of fine Ag-coated Cu wires and poly(ethylene naphthalene) monofilament fibers embedded in a polyurethane matrix. The yellow-emitting textile featured low turn-on voltage (5 V), high maximum brightness (>4000 cd m−2), good efficiency (3.4 cd A−1), and reasonable lifetime (180 h at >100 cd m−2). Uniform emission to the eye was attained from thin and highly flexible textiles featuring a large emission area of 42 cm2, without resorting to planarization of the partially wavy-shaped (valley-to-peak height = 2.7 μm) fabric electrode. The key enabling factors for the functional emissive textile are the characteristic in situ electrochemical doping of LEC devices, the 'dry' spray-sintering deposition of the active material, and the attractive mechanical, electronic and optical properties of the fabric-based electrode.

  • 3.
    Moberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Creating nanopatterned polymer films for use in light-emitting electrochemical cells2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Thermal nanoimprint lithography (T-NIL) is a cheap and fast technique to produce nanopatterns in polymeric materials. It creates these patterns by pressing a stamp down into a polymer film that has been heated above its glass transition temperature. These nanopatterned polymer films can be used in a wide variety of scientific fields, not the least the organic semiconductor industry. There the nanopatterned films have, among else, been used to improve the efficiency of organic light-emitting diodes (OLEDs). The light-emitting electrochemical cell (LEC), which is similar in structure to an OLED, also uses polymer films in their device structure but the light emitting layer also contains an electrolyte. However, it has not been shown if nanopatterns can improve LECs as well or if it is even possible to make an imprint in their polymer films that are mixed with an electrolyte.

    This thesis shows that T-NIL can be used to imprint nanopatterns in films made of poly(ethylene oxide) and the conjugated polymer Super Yellow. The best nanopatterns were produced by setting the imprint parameters to  85 °C, 10 bar, 1800 s for poly(ethylene oxide) and 115 °C, 20 bar, 1800 s for Super Yellow. Imprints were also performed on polystyrene but no nanopatterns could be produced. This was most likely because the stamp could not handle the high temperature that is required to make a nanopattern in polystyrene.

    The best imprint parameters of Super Yellow were then used to produce a pattern in a film made of Super Yellow mixed with the salt tetrahexylammonium tetrafluoroborate (THABF4) in order to be able to produce one imprinted and one reference LEC. The imprinted LEC had a luminosity of 139 cd/m2, an improvement of 20% compared to the reference’s 115 cd/m2 when operated under identical conditions.  The forward direction and the angular dependent electroluminescence spectrum of the imprinted LEC clearly showed an effect not observed in the reference.

    These findings show that the polymer films used in a LEC can be imprinted with a nanopattern by using T-NIL. The imprinted films can be used to create functional LECs that show different behavior and a higher luminosity compared to a non-imprinted reference. If these results can be repeated it might be the starting point of a brighter future.

  • 4.
    Skrypnychuk, Vasyl
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Vertical charge transport in conjugated polymers2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Conjugated polymers are novel organic electronic materials highly important for organic photovoltaic applications. Charge transport is one of the key properties which defines the performance of conjugated polymers in electronic devices.

    This work aims to explore the charge transport anisotropy in thin films of P3HT, one of the most common conjugated polymers. Using X-ray diffraction techniques and charge transport measurements, the relation between vertical charge transport through thin P3HT films and structure of the films was established.

    It was shown that particular orientations of crystalline domains of P3HT, namely face-on and chain-on, are beneficial for vertical charge transport. These orientations provide the efficient pathways for the charges to be transported vertically, either via π-π stacking interaction between the adjacent conjugated chains, or via the conjugated chain backbones. It was also demonstrated that particular orientations of crystallites are favourable for the formation of interconnected percolated pathways providing enhanced vertical charge transport across the film.

    Deposition of P3HT on most commonly used silicon substrates typically results in the formation of mostly edge-on orientation of crystallites which is unfavourable for vertical charge transport. Nanoimprint lithography was demonstrated as a powerful processing method for reorienting the edge-on crystalline domains of P3HT into chain-on (vertical) orientation. It is also shown that thin P3HT films with preferentially face-on orientations of crystallites can be deposited on graphene surface by spin coating.

    Using patterning of thin P3HT films by nanoimprint lithography, unprecedentedly high average vertical mobilities in the range of 3.1-10.6 cm2 V-1 s-1 were achieved in undoped P3HT.

    These results demonstrate that charge transport in thin films of a relatively simple and well-known conjugated polymer P3HT can be significantly improved using optimization of crystallinity,orientation of crystallites, polymer chain orientation and alignment in the films.

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