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  • 1.
    Abdipour, Morteza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för industridesign.
    Lorentzen, Lena
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för industridesign.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    A Design Research Lab—An Integrated Model to Identify Conscious and Unconscious Behavior in the Design Process2016Inngår i: Advances in Intelligent Systems and Computing: Design for Inclusion, Springer International Publishing Switzerland , 2016, Vol. 500, s. 553-563Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To understand how different design solutions affect users, designers traditionally use different evaluation methods that mainly rely on conscious feedback from the users. However, the complexity of human behaviour, where a large part is unconscious, point to a need for an extended tool box addressing the part not accessible to human conscious knowledge. Here, we describe a design research lab where traditional methods are complemented with tools to measure physiological signals influenced by emotional and sympathetic responses. These tools include galvanic skin response (GSR), electrocardiograph (ECG), and electroencephalograph (EEG). Typical sessions with acquired data of conscious and unconscious user reactions are described. The large body of data collected, which also require non-design expertise for interpretation, suggest that a further development towards simplified output data of the unconscious reactions is needed to allow wider use within industrial design work.

  • 2. Alarco, J A
    et al.
    Brorsson, G
    Olin, Håkan
    Department of Physics, Chalmers University of Technology/University of Göteborg.
    Olsson, E
    Early stages of growth of YBa2Cu3O7− high Tc superconducting films on (001) Y-ZrO2 substrates1994Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 75, s. 3202-3204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Theearly stages of growth of high quality YBa2Cu3O7− (YBCO) filmsgrown on (001) Y-ZrO2 (YSZ) substrates by pulsed laser depositionhave been studied using a combination of atomic force microscopyand transmission electron microscopy. A one unit cell thick YBCOlayer and relatively large CuO particles formed in the initialstages. Additional YBCO grew on top of the first layerin the form of one or a few unit cellhigh c-axis oriented islands about 30 nm in diameter. Therounded islands subsequently coalesced into faceted domains. Elongated Y2BaCuO5 particlesnucleated after the first layer of YBCO. A highly texturedBaZrO3 layer formed between the YSZ and the YBCO witha cube-on-cube dominant orientation relationship with respect to the YBCOfilm. Journal of Applied Physics is copyrighted by The American Institute of Physics.

  • 3.
    Alecrim, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Shimizu, Kenichi
    Umeå University.
    Andersson, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Exfoliation of MoS2 for paper based applications2014Konferansepaper (Annet vitenskapelig)
  • 4.
    Alecrim, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Shimizu, Kenichi
    Umeå University.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andersson, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Exfoliated MoS2 for paper based supercapacitors and photodetectors2014Inngår i: Collection of Extent Abstracts, 2014, s. 437-438Konferansepaper (Annet vitenskapelig)
  • 5.
    Alecrim, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andersson, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Hakan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Photoconductivity of bulk and liquid processed MoS22014Konferansepaper (Annet vitenskapelig)
  • 6.
    Alecrim, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andersson, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Exfoliated Layered Materials for Digital Fabrication2015Inngår i: NIP & Digital Fabrication Conference, 2015, Vol. 1, s. 192-194Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We introduced an exfoliation method of MoS2 in a 3% solution of sodium dodecyl surfactant at high concentration (i.e. 2 g/L). The bulk MoS2 was thinned by mechanical exfoliation between sand papers and the resulting powder was used to prepare dispersions by liquid exfoliation through probe sonication. The resulting dispersion consisted of very thin MoS2 nanosheets in surfactant solution with average lateral size around 126 nm. This may be interesting for applications in inkjet printed electronics.

  • 7.
    Andersson, Henrik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Manuilskiy, Anatoliy
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Contacting paper-based supercapacitors to printed electronics on paper substrates2012Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, nr 2, s. 476-480Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hybrid printed electronics, in which printed structures and silicon-based components co-exist will likely be among the first commercial solutions. In this case the paper substrate acts much in the same way as circuit boards, containing conductive tracks and acting as a carrier for the electrical components. It is important to consider the contacting of the components to be able to produce low resistance electrical contacts to the conductive tracks. Supercapacitors are able to deliver a large amount of current in a short time and are a good option for short term energy storage and if the printed product is to be used only one, or a few times, it can be the only power source needed. When manufacturing printed electronics, the overall resistance of the printed tracks as well as the contact resistance of the mounted components will add up to the total resistance of the system. A high resistance will cause a voltage drop from the power source to the component. This will waste power that goes to Joule heating and also the voltage and current available to components may be too low to drive them. If the intention is to use a power supply such as batteries or solar cells this becomes a limitation. In this article have been tested several conductive adhesives used to contact paper based supercapacitors to ink jet printed silver tracks on paper. The best adhesive gives about 0.3 Ω per contact, a factor 17 better compared to the worst which gave 5 Ω. The peak power that is possible to take out from a printed system with a flexible battery and super capacitors is about 10 times higher than compared with the same system with only the battery.

  • 8.
    Andersson, Henrik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Manuilskiy, Anatoliy
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Haller, Stefan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Sidén, Johan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Hummelgård, Christine
    Acreo Swedish ICT AB.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Nilsson, Hans-Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Assembling surface mounted components on ink-jet printed double sided paper circuit board2014Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 25, s. Art. no. 094002-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Printed electronics is a rapidly developing field where many components can already be manufactured on flexible substrates by printing or by other high speed manufacturing methods. However, the functionality of even the most inexpensive microcontroller or other integrated circuit is, at the present time and for the foreseeable future, out of reach by means of fully printed components. Therefore, it is of interest to investigate hybrid printed electronics, where regular electrical components are mounted on flexible substrates to achieve high functionality at a low cost. Moreover, the use of paper as a substrate for printed electronics is of growing interest because it is an environmentally friendly and renewable material and is, additionally, the main material used for many packages in which electronics functionalities could be integrated. One of the challenges for such hybrid printed electronics is the mounting of the components and the interconnection between layers on flexible substrates with printed conductive tracks that should provide as low a resistance as possible while still being able to be used in a high speed manufacturing process. In this article, several conductive adhesives are evaluated as well as soldering for mounting surface mounted components on a paper circuit board with inkjet printed tracks and, in addition, a double sided Arduino compatible circuit board is manufactured and programmed.

  • 9.
    Andersson, Henrik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Šuly, Pavol
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion. Tomas Bata University in Zlin, Zlin, Czech Republic.
    Thungström, Göran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Engholm, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Mašlík, Jan
    Tomas Bata University in Zlin, Zlin, Czech Republic.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    PEDOT: PSS thermoelectric generators printed on paper substrates2019Inngår i: Journal of Low Power Electronics and Applications, ISSN 2079-9268, Vol. 9, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Flexible electronics is a field gathering a growing interest among researchers and companies with widely varying applications, such as organic light emitting diodes, transistors as well as many different sensors. If the circuit should be portable or off-grid, the power sources available are batteries, supercapacitors or some type of power generator. Thermoelectric generators produce electrical energy by the diffusion of charge carriers in response to heat flux caused by a temperature gradient between junctions of dissimilar materials. As wearables, flexible electronics and intelligent packaging applications increase, there is a need for low-cost, recyclable and printable power sources. For such applications, printed thermoelectric generators (TEGs) are an interesting power source, which can also be combined with printable energy storage, such as supercapacitors. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), or PEDOT:PSS, is a conductive polymer that has gathered interest as a thermoelectric material. Plastic substrates are commonly used for printed electronics, but an interesting and emerging alternative is to use paper. In this article, a printed thermoelectric generator consisting of PEDOT:PSS and silver inks was printed on two common types of paper substrates, which could be used to power electronic circuits on paper. 

  • 10.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Characterization of nanographite and graphene produced in a high-pressure homogenizer2014Inngår i: Graphene Week 2014, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Supercapacitor electrodes are often made of porous carbon materials such as activated carbon, but also graphene was frequently used as active electrode material. Graphene can be produced by mechanical exfoliation, chemical exfoliation, chemical vapor deposition or other elaborate methods. These techniques are relatively expensive and produce small quantities only. Recently we presented a method to produce nanographite and graphene by mechanical exfoliation of graphite in a high-pressure homogenizer. In our contribution “Large-scale production of graphene” by Nicklas Blomquist we suggest to optimize the geometry of the shear zone and increase the feeding pressure to obtain a higher yield.

    In this study we evaluated the influence of these process optimizations on the structural and electrical properties of the nanographite-graphene mixture. The produced dispersions were characterized in terms of particle size and shape by using a particle size analyzer, a transmission electron microscope (TEM) and an atomic force microscope (AFM). In order to analyze the performance of the produced material as electrodes for supercapacitors, electrodes were produced by vacuum filtration. The electrodes were studied by sheet-resistance and capacitance measurements. Furthermore, the structure of the electrode surface and the cross section of the electrode were visualized by using a scanning electron microscope (SEM).

    Comparisons with previously produced nanographite-graphene dispersions showed an increase in yield of the exfoliated nanomaterials. The optimized shear zone increased the production of nanosized particles and flakes and enhanced the material quality.

  • 11.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Inexpensive production of graphene by mechanical treatment of graphite2014Inngår i: Graphene Study 2014, 2014Konferansepaper (Annet vitenskapelig)
  • 12.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Cellulose binders for electric double-layer capacitor electrodes: The influence of cellulose quality on electrical properties2018Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 141, s. 342-349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose derivatives are widely used as binders and dispersing agents in different applications. Binders composed of cellulose are an environmentally friendly alternative to oil-based polymer binding agents. Previously, we reported the use of cellulose nanofibers (CNFs) as binders in electrodes for electric double-layer capacitors (EDLCs). In addition to good mechanical stability, we demonstrated that CNFs enhanced the electrical performance of the electrodes. However, cellulose fibers can cover a broad range of length scales, and the quality requirements from an electrode perspective have not been thoroughly investigated. To evaluate the influence of fiber quality on electrode properties, we tested seven samples with different fiber dimensions that are based on the same kraft pulp. To capture the length scale from fibers to nanofibrils, we evaluated the performance of the untreated kraft pulp, refined fibers, microfibrillated cellulose (MFC) and CNFs. Electrodes with kraft pulp or refined fibers showed the lowest electrical resistivity. The specific capacitances of all EDLCs were surprisingly similar, but slightly lower for the EDLC with CNFs. The same electrode sample with CNFs also showed a slightly higher equivalent series resistance (ESR), compared to those of the other EDLCs. Graphite dispersions with MFC showed the best dispersion stability. 

  • 13.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Cellulose-based binder systems for electrochemical electrodes2015Konferansepaper (Annet vitenskapelig)
  • 14.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors2016Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 9, s. 1-12, artikkel-id e0163146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Symmetric electric double-layer capacitors (EDLCs) have equal masses of the same active material in both electrodes. However, having equal electrode masses may prevent the EDLC to have the largest possible specific capacitance if the sizes of the hydrated anions and cations in the electrolyte differ because the electrodes and the electrolyte may not be completely utilized. Here we demonstrate how this issue can be resolved by mass balancing. If the electrode masses are adjusted according to the size of the ions, one can easily increase an EDLC's specific capacitance. To that end, we performed galvanostatic cycling to measure the capacitances of symmetric EDLCs with different electrode mass ratios using four aqueous electrolytes-Na2SO4, H2SO4, NaOH, and KOH (all with a concentration of 1 M)-and compared these to the theoretical optimal electrode mass ratio that we calculated using the sizes of the hydrated ions. Both the theoretical and experimental values revealed lower-than-1 optimal electrode ratios for all electrolytes except KOH. The largest increase in capacitance was obtained for EDLCs with NaOH as electrolyte. Specifically, we demonstrate an increase of the specific capacitance by 8.6% by adjusting the electrode mass ratio from 1 to 0.86. Our findings demonstrate that electrode mass balancing is a simple and inexpensive method to increase the capacitance of EDLCs. Furthermore, our results imply that one can reduce the amount of unused material in EDLCs and thus decrease their weight, volume and cost.

  • 15.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Enhanced electrical and mechanical properties of nanographite electrodes for supercapacitors by addition of nanofibrillated cellulose2014Inngår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 251, nr 12, s. 2581-2586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Graphene and porous carbon materials are widely used as electrodes in supercapacitors. In order to form mechanically stable electrodes, binders can be added to the conducting electrode material. However, most bindersdegrade the electrical performance of the electrodes. Here we show that by using nanofibrillated cellulose(NFC) as binder the electrical properties, such as capacitance, were enhanced. The highest capacitance was measured at a NFC content of approximately 10% in ratio to the total amount of active material. NFC is a good ionconductor and improves the access of ions in the electrodes. Thus, electrodes made of a mixture of nanographite and NFC achieved larger capacitances in supercapacitors than electrodes with nanographite only. In addition to electrical properties, NFC enhanced the mechanical stability and wet strength of the electrodes significantly. Furthermore, NFC stabilized the aqueous nanographite dispersions, which improved the processability. Galvanostatic cycling was performed and an initial transient behaviour of the supercapacitors during the first cycles was observed. However, stabilized supercapacitors showed efficiencies of 98–100 %.

  • 16.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Enhanced electrical and mechanical properties of nanographite electrodes for supercapacitors by addition of nanobrillated cellulose2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Graphene and other porous carbon materials are widely used as electrodes in supercapacitors. In order to form mechanically stable electrodes, binders can be added to the conducting electrode material. However, most binders degrade the electrical performance of the electrodes. Here we show that by using nanobrillated cellulose (NFC) as binder the electrical properties, such as sheet-resistance, were enhanced. NFC is a good ion conductor and improves the access of ions to the electrodes. Thus electrodes made of a mixture of nanographite and NFC achieved larger capacitances in supercapacitors than electrodes with nanographite only. The lowest sheet-resistance and the highest capacitance were measured at NFC contents of 10{15% in ratio to the total amount of active material. Furthermore, NFC formed a network that improved the mechanical stability of the electrodes signicantly. Beside the mechanical stability, NFC stabilized the aqueous nanographite dispersion that was used to prepare the electrodes. NFC avoids the restacking of the delaminated graphene akes by forming a ber network between the graphene layers.

  • 17.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Influence of Electrode Mass Ratio on Capacitance of Supercapacitors2015Inngår i: Abstract Book, ISEECap 2015, 2015, s. 132-Konferansepaper (Fagfellevurdert)
  • 18.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Vilches, Ana Paola
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Supercapacitors with graphene coated paper electrodes2012Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, nr 2, s. 481-485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Paper based supercapacitors are prepared by stacking a paper between two graphene electrodes and soaking these in an aqueous electrolyte. We demonstrate that supercapacitors can easily be manufactured by using proven paper technologies. Several different electrode materials were compared and two types of contacting material, silver and graphite foil were tested. The influence of the paper used as separator was also investigated. The supercapacitors with a graphene-gold nanoparticle composite as electrodes showed a specific capacitance of up to 100 F/g and an energy density of 1.27 Wh/kg. The energy density can further be increased by using other electrolytes. The silver contacts showed a pseudo capacitance, which the graphite contacts did not. The papers tested had a minor effect on the capacitance, but they have an influence on the weight and the volume of the supercapacitor.

  • 19. Andzane, Jana
    et al.
    Tobin, Joseph M.
    Li, Zhonglai
    Prikulis, Juris
    Baxendale, Mark
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Holmes, justin D
    Erts, Donats
    Selection of Application Specific Single and Multi Walled Carbon Nanotubes by In Situ Characterization of Conductive and Field Emission Properties2007Inngår i: AZojono - Journal of Nanotechnology onlineArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The conductive and field emission properties of individual single and multi-walled carbon nanotubes, grown by chemical vapour and supercritical fluid deposition techniques, have been assessed using an in-situ transmission electron microscope-scanning tunnelling microscope (TEM-STM) technique. The conductivity and field emission measurements were obtained from nanotube-electrode distance and contact observations. Experimental field emission characteristics for all carbon nanotubes investigated fitted well to the Fowler-Nordheim equation when different work functions were applied. Differences in field emission and conductive properties are analysed and related to the structure of the carbon nanotubes. The method presented here is suitable for in situ selection of CNT with desired properties for particular electronic applications.

  • 20.
    Balliu, Enkeleda
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Engholm, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Laser-assisted reduction of graphene oxide for paper based large area flexible electronics2016Inngår i: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2016, Vol. 9736, artikkel-id 973610Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work we present a promising method for fabrication of conductive tracks on paper based substrates by laser assisted reduction of Graphene Oxide (GO). Printed electronics on paper based substrates is be coming more popular due to lower cost and recyclability. Fabrication of conductive tracks is of great importance where metal, carbon and polymer inks are commonly used. An emerging option is reduced graphene oxide (r-GO), which can be a good conductor. Here we have evaluated reduction of GO by using a 532 nm laser source, showing promising results with a decrease of sheet resistance from >100 M Ω/Sqr for unreduced GO down to 126 Ω/Sqr. without any observable damage to the paper substrates.

  • 21.
    Balliu, Enkeleda
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Engholm, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Öhlund, Thomas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Nilsson, Hans-Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Selective laser sintering of inkjet-printed silver nanoparticle inks on paper substrates to achieve highly conductive patterns2018Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, nr 1, artikkel-id 10408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Development of cost-effective and environmentally friendly manufacturing methods will enable important advances for the production of large-scale flexible electronics. Laser processing has shown to be a promising candidate that offers a fast and non-destructive way to produce highly conductive patterns on flexible substrates such as plastics. However, an emerging option with a lower environmental impact is instead the use of cellulose-based flexible substrates, such as paper. In this work we investigate the use of laser sintering of silver nanoparticle inks, which were inkjet-printed on three different types of paper. Patterns with a high conductivity could be manufactured where a special care was taken to prevent the substrates from damage by the intense laser light. We found that the best results was obtained for a photopaper, with a conductivity of 1.63 107 S/m corresponding to nearly 26% of the bulk silver conductivity. In addition, we demonstrate laser sintering to fabricate a fully functional near field communication tag printed on a photopaper. Our results can have an important bearing for the development of cost-effective and environmentally friendly production methods for flexible electronics on a large scale. 

  • 22.
    Balliu, Enkeleda
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Engholm, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Laser sintering of silver nano-particles inks printed on paper substrates2015Inngår i: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2015, s. Art. no. 935112-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work we have investigated the use of laser sintering of different ink-jet printed nano-particle inks (NPIs) on paper substrates. Laser sintering is shown to offer a fast and non-destructive way to produce paper based printed electronics. A continuous wave fiber laser source at 1064 nm is used and evaluated in combination with a galvo-scanning mirror system. A conductivity in order of 2.16 ∗ 107 S/m is reached for the silver NPI structures corresponding to nearly 35 % conductivity compared to that of bulk silver and this is achieved without any observable damage to the paper substrate. © 2015 SPIE.

  • 23. Bengtsson, Paul
    et al.
    Svensson, Krister
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    von Dorrien, Mikael
    Control signal for inertial slider2007Patent (Annet (populærvitenskap, debatt, mm))
  • 24. Blom, S.
    et al.
    Olin, Håkan
    Costa-Kramer, J.L.
    Garcia, N.
    Jonson, M.
    Serena, P.A.
    Shekhter, R.
    Free-electron model for mesoscopic force fluctuations in nanowires1998Inngår i: Physical Review B (Condensed Matter), ISSN 0163-1829, Vol. 57, nr 15, s. 8830-8833Artikkel i tidsskrift (Fagfellevurdert)
  • 25.
    Blomquist, Nicklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Alimadadi, Majid
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Olsen, Martin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Effects of Geometry on Large-scale Tube-shear Exfoliation of Multilayer Graphene and Nanographite in Water2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, nr 1, artikkel-id 8966Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrially scalable methods for the production of graphene and other nanographites are needed to achieve cost-efficient commercial products. At present, there are several available routes for the production of these materials but few allow large-scale manufacturing and environmentally friendly low-cost solvents are rarely used. We have previously demonstrated a scalable and low-cost industrial route to produce nanographites by tube-shearing in water suspensions. However, for a deeper understanding of the exfoliation mechanism, how and where the actual exfoliation occurs must be known. This study investigates the effect of shear zone geometry, straight and helical coil tubes, on this system based on both numerical simulation and experimental data. The results show that the helical coil tube achieves a more efficient exfoliation with smaller and thinner flakes than the straight version. Furthermore, only the local wall shear stress in the turbulent flow is sufficient for exfoliation since the laminar flow contribution is well below the needed range, indicating that exfoliation occurs at the tube walls. This explains the exfoliation mechanism of water-based tube-shear exfoliation, which is needed to achieve scaling to industrial levels of few-layer graphene with known and consequent quality.

  • 26.
    Blomquist, Nicklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Large-Scale Production of Nanographite by Tube-Shear Exfoliation in Water2016Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 4, artikkel-id e0154686Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The number of applications based on graphene, few-layer graphene, and nanographite is rapidly increasing. A large-scale process for production of these materials is critically needed to achieve cost-effective commercial products. Here, we present a novel process to mechanically exfoliate industrial quantities of nanographite from graphite in an aqueous environment with low energy consumption and at controlled shear conditions. This process, based on hydrodynamic tube shearing, produced nanometer-thick and micrometer-wide flakes of nanographite with a production rate exceeding 500 gh-1 with an energy consumption about 10 Whg-1. In addition, to facilitate large-area coating, we show that the nanographite can be mixed with nanofibrillated cellulose in the process to form highly conductive, robust and environmentally friendly composites. This composite has a sheet resistance below 1.75 Ω/sq and an electrical resistivity of 1.39×10-4 Ωm and may find use in several applications, from supercapacitors and batteries to printed electronics and solar cells. A batch of 100 liter was processed in less than 4 hours. The design of the process allow scaling to even larger volumes and the low energy consumption indicates a low-cost process.

  • 27.
    Blomquist, Nicklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Koppolu, R.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Toivakka, M.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Influence of Substrate in Slot-die Coating of Nanographite/Nanocelluose Electrodes for SupercapacitorsManuskript (preprint) (Annet vitenskapelig)
  • 28.
    Blomquist, Nicklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap. STT Emtec AB, Sundsvall.
    Wells, Thomas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Metal-free supercapacitor with aqueous electrolyte and low-cost carbon materials2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 39836Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electric double-layer capacitors (EDLCs) or supercapacitors (SCs) are fast energy storage devices with high pulse efficiency and superior cyclability, which makes them useful in various applications including electronics, vehicles and grids. Aqueous SCs are considered to be more environmentally friendly than those based on organic electrolytes. Because of the corrosive nature of the aqueous environment, however, expensive electrochemically stable materials are needed for the current collectors and electrodes in aqueous SCs. This results in high costs for a given energy-storage capacity. To address this, we developed a novel low-cost aqueous SC using graphite foil as the current collector and a mix of graphene, nanographite, simple water-purification carbons and nanocellulose as electrodes. The electrodes were coated directly onto the graphite foil by using casting frames and the SCs were assembled in a pouch cell design. With this approach, we achieved a material cost reduction of greater than 90% while maintaining approximately one-half of the specific capacitance of a commercial unit, thus demonstrating that the proposed SC can be an environmentally friendly, low-cost alternative to conventional SCs.

  • 29. Bogdanov, A L
    et al.
    Erts, D
    Nilsson, B
    Olin, Håkan
    Department of Physics, Chalmers University of Technology.
    Fabrication of arrays of nanometer size test structures for scanning probe microscope tips characterization1994Inngår i: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 12, nr 6, s. 3681-3684Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A problem in scanning probe microscopy (SPM) is the unknown shape of the probing tip. Generally, the image is a convolution between the shape of the tip and the surface. Information of the shape of the probe may be gained by imaging very sharp tips. Here we present a method for making two-dimensional arrays of very sharp tips. The tip arrays were made of silicon using electron beam lithography with subsequent ion-beam etching. To achieve the best possible resolution, ultrasonic excitation was used during development of the bilayered PMMA resist. Thus, openings in the resist with size nearly equal to the spot size of the writing e-beam have been obtained. A further decrease of the radius of the tips was obtained by the choice of appropriate thickness for the masking NiCr layer. The tips were conical with a height up to 100 nm with a radius of the tip down to 10 nm. The tips were suitable for study of the shape of AFM probe tips, under condition that the tip array samples were rinsed in water prior to the measurement. Without the rinsing procedure, strong sticking forces between the probe and the sample would have eroded both of them. The regularity of the array provided an easy way to calibrate the lateral motion of the scanner.

     

  • 30. Brauer, H E
    et al.
    Ekvall, I
    Olin, Håkan
    Starnberg, H I
    Wahlström, E
    Sodium intercalation of VSe2 studied by photoemission and scanning tunneling microscopy1997Inngår i: ECASIA 97: 7TH EUROPEAN CONFERENCE ON APPLICATIONS OF SURFACE AND INTERFACE ANALYSIS, 1997, s. 599-602Konferansepaper (Fagfellevurdert)
  • 31. Brauer, H.E.
    et al.
    Ekvall, I.
    Olin, Håkan
    Starnberg, H.I.
    Wahlström, E.
    Hughes, H.P.
    Strocov, V.N.
    Na intercalation of VSe2 studied by photoemission and scanning tunneling microscopy1997Inngår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 55, nr 15, s. 10022-10026Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In situ Na intercalation of the layered compound VSe2 has been studied with photoemission and scanning tunneling microscopy. Core-level spectroscopy proves that Na deposited in UHV onto the VSe2 surface rapidly intercalates, leaving only small amounts at the surface. The scanning tunneling microscopy measurements show that the intercalated Na is not uniformly distributed between the VSe2 layers, but preferentially in two-dimensional islands. Thus the surface region is divided into intercalated and nonintercalated areas. Hole-like features in the intercalated areas are interpreted as locally missing Na.

  • 32. Breitholtz, M.
    et al.
    Kihlgren, T.
    Lindgren, S.Å.
    Olin, Håkan
    Wallden, L.
    Wahlström, E.
    Metal quantum wells with all electrons confined: Na films and islands on graphite2001Inngår i: Physical Review B (Condensed Matter and Materials Physics), ISSN 0163-1829, Vol. 64, nr 7, s. 3301-3304Artikkel i tidsskrift (Fagfellevurdert)
  • 33. Brorsson, G
    et al.
    Alarco, J A
    Ivanov, Z G
    Olin, Håkan
    CHALMERS UNIV TECHNOL, DEPT PHYS.
    Nilsson, P A
    Claeson, T
    Study of in situ laser deposited YBCO thin-films1990Inngår i: Journal of the less-common metals, ISSN 0022-5088, Vol. 164, nr Part A, s. 383-390Artikkel i tidsskrift (Fagfellevurdert)
  • 34. Claeson, T.
    et al.
    Delsing, P.
    Ivanov, Z.
    Kubatkin, S.E.
    Kuzmin, L.
    Olin, Håkan
    Petrashov, V.
    Shaikhadarov, R.S.
    Tzalenchuk, A.
    Garcia, N.
    Nieto-Vesperinas, M.
    Rohrer, H.
    Transport in mesoscopic superconductros and superconducting/normal metal contacts1998Inngår i: 1998 CATALOG of E -SeriesNanoscale Science and Technology. Resulting from ARW, Toledo (Spain), 1997, Dordrecht: Kluwer Academic Publ. , 1998, , s. 355Konferansepaper (Fagfellevurdert)
  • 35. Costa-Kramer, J.L.
    et al.
    Garcia, N.
    Jonson, M.
    Krive, I.V.
    Olin, Håkan
    Serena, P.A.
    Shekhter, R.I.
    Garcia, N.
    Nieto-Vesperinas, M.
    Rohrer, H.
    Low voltage nonlinear conductance of gold nanowires: Room temperature Coulomb blockade effect1998Inngår i: 1998 CATALOG of E -SeriesNanoscale Science and Technology: 1998 CATALOG of E -SeriesResulting from ARW, Toledo (Spain), 1997, Dordrecht: Kluwer Academic Publ. , 1998, , s. 355Konferansepaper (Annet vitenskapelig)
  • 36. Costa-Kramer, J.L.
    et al.
    Garcia, N.
    Olin, Håkan
    Department of Physics, Chalmers University of Technology and Göteborg University.
    Conductance quantization histograms of gold nanowires at 4 K1997Inngår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 55, nr 19, s. 12910-12913Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Driving a scanning tunneling microscope (STM) tip into a metallic surface and pulling it out afterwards results in the formation of a nanometer-sized wire (nanowire) between the electrodes. The electrical conduction measured during this process shows signs of quantized conductance in units of G0=2e2/h. Due to the inherent irreproducibility of the measured conductance curves, the standard technique has been to construct histograms with a few hundred selected curves. These histograms, for gold nanowires at room temperature, have shown three to four peaks at integer values of 2e2/h, while in a low-temperature mechanically controlled break junction study, with statistics using only 65 curves, only the first peak has been reported. A proposed explanation for this apparent experimental discrepancy has been a higher nanowire temperature arising from the higher retraction speed used in scanning tunneling microscopy measurements. However, our simple estimation using macroscopic heat transport theory produces a very low temperature rise, less than 1 μK. In this work, an improved statistical study is presented, where histograms built with thousands of consecutive gold contact breakage experiments at 4 K show up to seven conductance peaks. Thus, no significant differences with our previous room-temperature (RT) studies are observed, pointing to a conductance quantization behavior that is the same at low, intermediate, and high (RT) temperatures.

  • 37. Costa-kramer, J.L.
    et al.
    Garcia, N
    Olin, Håkan
    Department of Physics, Chalmers University of Technology and Göteborg University, SE-41296 Göteborg, Sweden .
    Conductance quantization in bismuth nanowires at 4 K1997Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 78, nr 26, s. 4990-4993Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conductance experiments on Bi nanowires at 4 K, obtained with a scanning tunneling microscope, are presented. The conductance of these Bi nanocontacts, formed between two Bi electrodes, exhibits plateaus at quantized values of G0 =  2e2/h, remaining basically constant during electrode separations of about 50 nm. This is the first time that such plateaus have been observed in semimetals. The histogram of conductance values, constructed with thousands of consecutive contact breakage conductance experiments, exhibits clear peaks at G0 and 2G0.

  • 38. Crowley, T.A.
    et al.
    Ziegler, K.J.
    Lyons, D.M.
    Erts, D.
    Olin, Håkan
    Chalmers University of Technology.
    Morris, M.A.
    Holmes, J.D.
    Synthesis of metal and metal oxide nanowires and nanotube arrays within a mesoporous silica template2003Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 15, nr 18, s. 3518-3522Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metallic nanowires of cobalt, copper, and iron oxide magnetite (Fe3O4) have been synthesized within the pores of mesoporous silica using a supercritical fluid inclusion technique. The mesoporous matrix provides a means of producing a high density of stable, hexagonally ordered arrays of highly crystalline nanowires. The formation of the metal and metal oxide nanowires within the silica mesopores was confirmed by transmission electron microscopy (TEM), N2 adsorption experiments, and powder X-ray diffraction (PXRD). The mechanism of nanowire formation within the mesopores appears to occur through the initial binding and coating of the pore walls with the metal atoms to form tubelike structures within the mesoporous template. The thickness of these tubes subsequently increases with further metal deposition until nanowires are formed. Additionally, the crystal structure of the cobalt nanowires formed within the mesoporous template can be readily changed by manipulating the density of the supercritical fluid phase.

     

  • 39. Danilov, Andrey
    et al.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Angenete, Johan
    Optical probing in electron microscopes2010Patent (Annet (populærvitenskap, debatt, mm))
  • 40. Davidsson, P
    et al.
    Olin, Håkan
    Department of Physics, Chalmers University of Technology and University of Göteborg.
    Vortex mapping on gold covered conventional type II superconductors using the very low temperature tunnelling microscope1994Inngår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 194-196, nr Part 1, s. 375-376Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have used a dilution refrigerator cooled STM for investigating the vortex state in lead-bismuth alloy 4000Aofilms. The vortices were recognized by the decreasing dynamic conductance near the gap voltage when the instrument was operated in its normal feed back mode. A clean surface suitable for tunneling was maintained by a 75Aolayer of gold deposited on top of the sample film. The temperature was kept at 80 mK and magnetic fields between 0 and 0.2 T were used.

     

  • 41. Davidsson, P
    et al.
    Olin, Håkan
    Department of Physics, Chalmers Uniuersity of Technology.
    Persson, M
    Pehrson, S
    DESIGN AND OPERATION OF A LOW-TEMPERATURE SCANNING TUNNELING MICROSCOPE SUITABLE FOR OPERATION BELOW 1-K1992Inngår i: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 42-44, s. 1470-1475Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A scanning tunneling microscope suitable for very low temperatures has been designed, and preliminary testing has been

    carried out. In order to improve cooling and temperature uniformity the instrument is arranged for operation immersed in

    the 3He-4He mixture inside the mixing chamber of a small dilution refrigerator. A discussion of the specific problems

    present in the design of this kind of an instrument is given as well as a description of our design. Special attention is given to

    the vacuum sealing and vibration-damping solutions required.

  • 42.
    Edvardsson, Sverker
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Karlsson, Kristoffer
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för ämnesdidaktik och matematik.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    corr3p_tr: A particle approach for the general three-body problem2016Inngår i: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 200, s. 259-273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work presents a convenient way to solve the non-relativistic Schrodinger equation numerically for a general three-particle system including full correlation and mass polarization. Both Coulombic and non-Coulombic interactions can be studied. The eigensolver is based on a second order dynamical system treatment (particle method). The Hamiltonian matrix never needs to be realized. The wavefunction evolves towards the steady state solution for which the Schrodinger equation is fulfilled. Subsequent Richardson extrapolations for several meshes are then made symbolically in matlab to obtain the continuum solution. The computer C code is tested under Linux 64 bit and both double and extended precision versions are provided. Test runs are exemplified and, when possible, compared with corresponding values in the literature. The computer code is small and self contained making it unusually simple to compile and run on any system. Both serial and parallel computer runs are straight forward. Program summary Program title: corr3p_tr Catalogue identifier: AEYR_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEYR_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.ukilicence/licence.html No. of lines in distributed program, including test data, etc.: 15025 No. of bytes in distributed program, including test data, etc.: 156430 Distribution format: tar.gz Programming language: ANSI C. Computer: Linux 64bit PC. Operating system: Linux 64bit. RAM: 300 M bytes Classification: 2.7, 2.8, 2.9. Nature of problem: The Schrodinger equation for an arbitrary three -particle system is solved using finite differences and a fast particle method for the eigenvalue problem [20, 21, 23]. Solution method: A fast eigensolver is applied (see Appendix). This solver works for both symmetrical and nonsymmetrical matrices (which opens up for more accurate nonsymmetrical finite difference expressions to be applied at the boundaries). The three-particle Schrodinger equation is transformed in two major steps. First step is to introduce the function Q(r(1), (r)2, mu) = r(1)r(2)(1 - mu(2))phi(r(1), r(2), mu), where mu = cos (0(12)). The cusps (r(1) = r(2), mu = 1) are then transformed into boundary conditions. The derivatives of Qare then continuous in the whole computational space and thus the finite difference expressions are well defined. Three-particle coalescence (r(1) = r(2) = 0, mu) is treated in the same way. The second step is to replace Q(r(1), r(2), mu) with (2,root x(1)x(2))(-1)Q(x(1) x(2), mu). The space (x(1), x(2), mu) is much more appropriate for a finite difference approach since the square roots x(1) = root r(1), x(2) = root r(2) allow the boundaries to be much further out. The non-linearity of the x-grid also leads to a finer description near the nucleus and a coarser one further out thus resulting in a saving of grid points. Also, in contrast to the usual variable r(12), we have instead used mu which is an independent variable. This simplifies the mathematics and numerical treatments. Several different grids can naturally run completely independent of each other thus making parallel computations trivial. From several grid results the physical property of interest is extrapolated to continuum space. The extrapolations are made in a matlab m-script where all computations can be made symbolically so the loss of decimal figures are minimized during this process. The computer code, including correlation effects and mass polarization, is highly optimized and deals with either triangular or quadratic domains in (x(1), x(2)). Restrictions: The amount of CPU time may become unreasonable for states needing boundary conditions very far beyond the origin. Also if the condition number of the corresponding Hamiltonian matrix is very high, the number of iterations will grow. The use of double precision computations also puts a limit on the accuracy of extrapolated results to about 6-7 decimal figures. Unusual features: The numerical solver is based on a particle method presented in [20, 21, 23]. In the Appendix we provide specific details of dealing with eigenvalue problems. The program uses a 64 bit environment (Linux 64bit). Parallel runs can be made conveniently through a simple bash script. Additional comments: The discretized wavefunction is complete on every given grid. New interactions can therefore conveniently be added to the Hamiltonian without the need to seek for an appropriate basis set. Running time: Given a modern CPU such as Intel core i5 and that the outer boundary conditions of r(1) and r(2) is limited to, say 16 atomic units, the total CPU time of totally 10 grids of a serial run is typically limited to a few minutes. One can then expect about 6-7 correct figures in the extrapolated eigenvalue. A single grid of say h(1) = h(2) = h(3) = 1/16 converges in less than 1 s (with an error in the eigenvalue of about 1 percent). Parallel runs are possible and can further minimize CPU times for more demanding tasks. References: [20] S. Edvardsson, M. Gulliksson, and J. Persson.). Appl. Mech. ASME, 79 (2012) 021012. [21] S. Edvardsson, M. Neuman, P Edstrom, and H. Olin. Comp. Phys. Commun. 197 (2015) 169. [23] M. Neuman, S. Edvardsson, P. Edstrom, Opt. Lett. 40 (2015) 4325.

  • 43.
    Edvardsson, Sverker
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Neuman, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Edström, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Gulliksson, Mårten
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Role of the particle method DFPM for solving linear equationsManuskript (preprint) (Annet vitenskapelig)
  • 44.
    Edvardsson, Sverker
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Neuman, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Edström, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Solving equations through particle dynamics2015Inngår i: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 197, s. 169-181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present work evaluates a recently developed particle method (DFPM). The basic idea behind this method is to utilize a Newtonian system of interacting particles that through dissipation solves mathematical problems. We find that this second order dynamical system results in an algorithm that is among the best methods known. The present work studies large systems of linear equations. Of special interest is the wide eigenvalue spectrum. This case is common as the discretization of the continuous problem becomes dense. The convergence rate of DFPM is shown to be in parity with that of the conjugate gradient method, both analytically and through numerical examples. However, an advantage with DFPM is that it is cheaper per iteration. Another advantage is that it is not restricted to symmetric matrices only, as is the case for the conjugate gradient method. The convergence properties of DFPM are shown to be superior to the closely related approach utilizing only a first order dynamical system, and also to several other iterative methods in numerical linear algebra. The performance properties are understood and optimized by taking advantage of critically damped oscillators in classical mechanics. Just as in the case of the conjugate gradient method, a limitation is that all eigenvalues (spring constants) are required to be of the same sign. DFPM has no other limitation such as matrix structure or a spectral radius as is common among iterative methods. Examples are provided to test the particle algorithm’s merits and also various performance comparisons with existent numerical algorithms are provided.

  • 45. Ekvall, I.
    et al.
    Brauer, H.E.
    Olin, Håkan
    Starnberg, H.I.
    Wahlström, E.
    Scanning tunneling microscopy and spectroscopy of Na intercalation in VSe21998Inngår i: Applied Physics A (Materials Science Processing), ISSN 0947-8396, Vol. 66, s. 197-201Artikkel i tidsskrift (Fagfellevurdert)
  • 46. Ekvall, I.
    et al.
    Brauer, H.E.
    Wahlström, E.
    Olin, Håkan
    Locally modified charge-density waves in Na intercalated VSe2 studied by scanning tunneling microscopy and spectroscopy1999Inngår i: Physical Review B (Condensed Matter), ISSN 0163-1829, Vol. 59, nr 11, s. 7751-7761Artikkel i tidsskrift (Fagfellevurdert)
  • 47. Ekvall, I.
    et al.
    Kim, Ju-Jin
    Olin, Håkan
    Atomic and electronic structures of the two different layers in 4Hb-TaS2 at 4.2 K1997Inngår i: Physical Review B (Condensed Matter), ISSN 0163-1829, Vol. 55, nr 11, s. 6758-6761Artikkel i tidsskrift (Fagfellevurdert)
  • 48. Ekvall, I.
    et al.
    Wahlström, E.
    Claeson, D.
    Olin, Håkan
    Olsson, E.
    Preparation and characterization of electrochemically etched W tips for STM1999Inngår i: Measurement Science & Technology, ISSN 0957-0233, Vol. 10, nr 1, s. 11-18Artikkel i tidsskrift (Fagfellevurdert)
  • 49.
    Ekvall, Inger
    et al.
    Department of Physics, Chalmers University of Technology and Göteborg University.
    Kim, Ju-Jin
    Department of Physics, Chonbuk National University, 560-756 Chonju, Korea.
    Olin, Håkan
    Department of Physics, Chalmers University of Technology and Göteborg University.
    Scanning tunneling spectroscopy of 1T-TaS2 between 300 K and 40 K1996Inngår i: Czechoslovak Journal of Physics, ISSN 0011-4626, E-ISSN 1572-9486, Vol. 46, s. 2601-2602Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have used scanning tunneling spectroscopy to measure temperature dependent tunneling spectra of 1T-TaS2 from room temperature to ∼ 40 K. An abrupt transition from the charge-density-wave induced broad depletion to an opening of a deep pseudo gap was observed within ∼ 1 K of the nearly commensurate to commensurate transition temperature. This pseudo gap was deep enough to form localized states at the Fermi level. Our tunneling results therefore suggest, in contrast to inverse photoelectron spectroscopy, that the band splitting of the Ta 5d band is due to the electron correlation effect.

  • 50. Enoksson, P.
    et al.
    Nafari, A.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Althoff, A.
    Danilov, A.
    Dahlström, J.
    MEMS Nanoindenter2010Patent (Annet (populærvitenskap, debatt, mm))
12345 1 - 50 of 201
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