miun.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Hummelgård, Christine
Alternative names
Publications (10 of 13) Show all publications
Gaynullin, B., Bryzgalov, M., Hummelgård, C. & Rödjegard, H. (2016). A practical solution for accurate studies of NDIR gas sensor pressure dependence. Lab test bench, software and calculation algorithm. In: 2016 IEEE SENSORS: . Paper presented at 2016 IEEE SENSORS. Orlando, FL, USA: IEEE
Open this publication in new window or tab >>A practical solution for accurate studies of NDIR gas sensor pressure dependence. Lab test bench, software and calculation algorithm
2016 (English)In: 2016 IEEE SENSORS, Orlando, FL, USA: IEEE, 2016Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a lab test system for studying pressure dependence of NDIR gas sensors in accuracy demanding applications. The test system consists of a hardware test bench, user software (LabVIEW based) and a calculation algorithm. The lab test bench provides highly accurate test environment for collecting characterization data. The software and the calculation algorithm process the data to derive accurate compensation parameters for each specific design of NDIR sensors. The compensation parameters are used to normalize the measured concentration to the values valid for standard atmospheric pressure.

Place, publisher, year, edition, pages
Orlando, FL, USA: IEEE, 2016
Keywords
NDIR, sensor, pressure, compensation, carbon dioxide
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-34733 (URN)10.1109/ICSENS.2016.7808828 (DOI)978-1-4799-8287-5 (ISBN)
Conference
2016 IEEE SENSORS
Available from: 2018-10-17 Created: 2018-10-17 Last updated: 2018-12-11Bibliographically approved
Andersson, H., Manuilskiy, A., Haller, S., Hummelgård, M., Sidén, J., Hummelgård, C., . . . Nilsson, H.-E. (2014). Assembling surface mounted components on ink-jet printed double sided paper circuit board. Nanotechnology, 25, Art. no. 094002
Open this publication in new window or tab >>Assembling surface mounted components on ink-jet printed double sided paper circuit board
Show others...
2014 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 25, p. Art. no. 094002-Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2014
Keywords
printed electronics, component mounting, conductive adhesives, ink jet, printed circuit board, silver nano particle ink
National Category
Nano Technology
Identifiers
urn:nbn:se:miun:diva-21474 (URN)10.1088/0957-4484/25/9/094002 (DOI)000331573500004 ()2-s2.0-84894165167 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Available from: 2014-02-28 Created: 2014-02-28 Last updated: 2017-12-05Bibliographically approved
Hummelgård, C., Bäckström, J., Olin, H., Karlsson, R., Cornell, A., Habibur Rahman, S. & Eriksson, S. (2013). Physical and electrochemical properties of cobalt doped (ti,ru)O2 electrode coatings. Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, 178(20), 1515-1522
Open this publication in new window or tab >>Physical and electrochemical properties of cobalt doped (ti,ru)O2 electrode coatings
Show others...
2013 (English)In: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 178, no 20, p. 1515-1522Article in journal (Refereed) Published
Abstract [en]

The physical and electrochemical properties of ternary oxides Ti 0.7Ru0.3-xCoxO2 (x = 0.093 and x = 0) have been investigated and compared. Samples of three different thicknesses were prepared by spin-coating onto polished titanium to achieve uniform and well-defined coatings. The resulting electrodes were characterized with a variety of methods, including both physical and electrochemical methods. Doping with cobalt led to a larger number of micrometer-sized cracks in the coating, and coating grains half the size compared to the undoped samples (10 instead of 20 nm across). This is in agreement with a voltammetric charge twice as high, as estimated from cyclic voltammetry. There is no evidence of a Co 3O4 spinel phase, suggesting that the cobalt is mainly incorporated in the overall rutile structure of the (Ti,Ru)O2. The doped electrodes exhibited a higher activity for cathodic hydrogen evolution compared to the undoped electrodes, despite the fact that one third of the active ruthenium was substituted with cobalt. For anodic chlorine evolution, the activity was similar for both electrode types.

Keywords
Chlorine evolution, Cobaltdoping, DSA®, Hydrogen evolution, Polarization curves, XRD
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-17211 (URN)10.1016/j.mseb.2013.08.018 (DOI)000327830000024 ()2-s2.0-84887055267 (Scopus ID)
Available from: 2012-10-18 Created: 2012-10-18 Last updated: 2017-12-07Bibliographically approved
Hummelgård, C., Olin, H., Gustafsson, J., Cornell, A. & Bäckström, J. (2013). Spin coated titanium-ruthenium oxide thin films. Thin Solid Films, 536, 74-80
Open this publication in new window or tab >>Spin coated titanium-ruthenium oxide thin films
Show others...
2013 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 536, p. 74-80Article in journal (Other academic) Published
Abstract [en]

Substrates of different roughness spin coated with Ti0.7Ru 0.3O2 films have been evaluated as model system for fundamental studies of the industrially and scientifically interesting (Ti,Ru)O2 based electrodes. The approach allowed for much more accurate control over the material synthesis than the traditionally used brush-, dip-, or spray-coating, on titanium-metal substrates. It moreover yielded well-defined samples suitable for basic studies of the surface properties that are of fundamental importance for understanding the electrochemical functionality of the electrode. We have compared the films on silicon substrates to films prepared by spin coating the same material on titanium-metal substrates. Samples have been characterized using atomic force microscopy (AFM), X-ray diffraction, scanning electron microscopy (SEM), and cyclic voltammetry. The samples displayed a uniformity of the films appropriate for AFM characterization. The smoother the substrate the less cracks in the coating. Using easily broken silicon wafers as substrate, a straightforward sample preparation technique was demonstrated for cross-section SEM. In addition, using high spinning velocities we have deposited the oxide films directly on silicon-nitride grids, thin enough to allow for studies with transmission electron microscopy without further sample preparation.

Keywords
Atomic force microscopy; Cross-section scanning electron microscopy; Ruthenium dioxide-titanium dioxide; Spin coating; Transmission electron microscopy; X-ray diffraction
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-17210 (URN)10.1016/j.tsf.2013.03.044 (DOI)000318974800010 ()2-s2.0-84877696954 (Scopus ID)
Note

Published online 2 April 2013.

Available from: 2012-10-18 Created: 2012-10-18 Last updated: 2017-12-07Bibliographically approved
Gustafsson, J., Hummelgård, C., Bäckström, J., Odnevall Wallinder, I., Habibur Rahman, S. M., Lindbergh, G., . . . Cornell, A. (2012). In-situ activated hydrogen evolution by molybdate addition to neutral and alkaline electrolytes. Journal of electrochemical science and engineering, 2(3), 105-120
Open this publication in new window or tab >>In-situ activated hydrogen evolution by molybdate addition to neutral and alkaline electrolytes
Show others...
2012 (English)In: Journal of electrochemical science and engineering, ISSN 1847-9286, Vol. 2, no 3, p. 105-120Article in journal (Refereed) Published
Abstract [en]

Activation of the hydrogen evolution reaction (HER) by in-situ addition of Mo(VI) to the electrolyte has been studied in alkaline and pH neutral electrolytes, the latter with the chlorate process in focus. Catalytic molybdenum containing films formed on the cathodes during polarization were investigated using scanning electron microscopy (SEM), energy-dispersive X ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), and X ray fluorescence (XRF). In-situ addition of Mo(VI) activates the HER on titanium in both alkaline and neutral electrolytes and makes the reaction kinetics independent of the substrate material. Films formed in neutral electrolyte consisted of molybdenum oxides and contained more molybdenum than those formed in alkaline solution. Films formed in neutral electrolyte in the presence of phosphate buffer activated the HER, but were too thin to be detected by EDS. Since molybdenum oxides are generally not stable in strongly alkaline electrolyte, films formed in alkaline electrolyte were thinner and probably co-deposited with iron. A cast iron molybdenum alloy was also investigated with respect to activity for HER. When polished in the same way as iron, the alloy displayed a similar activity for HER as pure iron.

Keywords
Molybdate, molybdenum dioxide, electrodeposition, electrolysis
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-17212 (URN)10.5599/jese.2012.0015 (DOI)
Available from: 2012-10-18 Created: 2012-10-18 Last updated: 2016-10-17Bibliographically approved
Hummelgård, C. (2012). Nanoscaled Structures of Chlorate Producing Electrodes. (Doctoral dissertation). Sundsvall: Mid Sweden University
Open this publication in new window or tab >>Nanoscaled Structures of Chlorate Producing Electrodes
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Sodium chlorate is mainly used for production of chlorine dioxide (a pulp bleaching agent). Sodium chlorate is produced by an electrochemical process where chloride ions (from sodium chloride dissolved in water) are oxidized to chlorine on the anodes and hydrogen is evolved on the cathodes. The anode of this process consists of a metal plate coated with a catalytically active metal oxide film. The electrocatalytic properties of the anode coating film have been widely investigated due to the great importance of these electrodes in the electrochemical industry. The material properties are, however, not as well investigated, and the studies described in this thesis are an attempt to remedy this.

Several standard material characterization methods were used, such as SEM, TEM, AFM, EDX, XRD, porosimetry and DSC. Also, a novel model system based on spin coated electrode films on smooth substrates was developed. The model system provided a way to design samples suitable for e.g. TEM, where the sample thickness is limited to maximum of 100 nm. This is possible due to the ability to control the film thickness by the spinning velocity when using the spin coating technique.

It was shown here that the anode coating has a nanostructure. It consists of grains, a few tens of nanometers across. The nanostructure leads to a large effective area and thus provides an explanation of the superior catalytic properties of these coatings. The grains were also shown to be monocrystalline. The size of these grains and its origin was investigated. The calcination temperature, the precursor salt and (if any) doping material all affected the grain size. A higher calcination temperature yielded larger grains and doping with cobalt resulted in smaller grains and therefore a larger real area of the coating. Some preparation conditions also affected the microstructure of the coating; such as substrate roughness. The microstructure is for example the cracked-mud structure. A smoother substrate gave a lower crack density.

The cathode of chlorate production is usually an uncoated metal plate, therefore 'less catalytically active'. It is, however, possible to activate the cathode by for example in situ additions to the electrolyte. It was shown here that sufficient addition of molybdate to the electrolyte resulted in a molybdenum film deposited on the cathode and thereby an increase of its surface area and an activation the hydrogen evolution reaction.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2012
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 134
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-17206 (URN)978-91-87103-35-3 (ISBN)
Public defence
2012-11-09, M102, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2012-10-18 Created: 2012-10-17 Last updated: 2012-11-30Bibliographically approved
Gustafsson, J., Li, G., Hummelgård, C., Bäckström, J. & Cornell, A. (2012). On the suppression of cathodic hypochlorite reduction by electrolyte additions of molybdate and chromate ions. Journal of electrochemical science and engineering, 2(4), 185-198
Open this publication in new window or tab >>On the suppression of cathodic hypochlorite reduction by electrolyte additions of molybdate and chromate ions
Show others...
2012 (English)In: Journal of electrochemical science and engineering, ISSN 1847-9286, Vol. 2, no 4, p. 185-198Article in journal (Refereed) Published
Abstract [en]

The goal of this study was to gain a better understanding of the feasibility of replacing Cr(VI) in the chlorate process by Mo(VI), focusing on the cathode reaction selectivity for hydrogen evolution on steel and titanium in a hypochlorite containing electrolyte. To evaluate the ability of Cr(VI) and Mo(VI) additions to hinder hypochlorite reduction, potential sweep experiments on rotating disc electrodes and cathodic current efficiency (CE) measurements on stationary electrodes were performed. Formed electrode films were investigated with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cathodic hypochlorite reduction is hindered by the Mo-containing films formed on the cathode surface after Mo(VI) addition to the electrolyte, but much less efficient compared to Cr(VI) addition. Very low levels of Cr(VI), in the mM range, can efficiently suppress hypochlorite reduction on polished titanium and steel. Phosphate does not negatively influence the CE in the presence of Cr(VI) or Mo(VI) but the Mo-containing cathode films become thinner if the electrolyte during the film build-up also contains phosphate. For a RuO2-TiO2 anode polarized in electrolyte with 40 mM Mo(VI), the anode potential increased and increased molybdenum levels were detected on the electrode surface

Keywords
Current efficiency, hydrogen evolution, in-situ additives, cathode, electrolysis, EDS, SEM, potential sweeps, galvanostatic polarization
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-17213 (URN)10.5599/jese.2012.0021 (DOI)
Available from: 2012-10-18 Created: 2012-10-18 Last updated: 2016-10-17Bibliographically approved
Malmgren, C., Eriksson, A. K., Cornell, A., Bäckström, J., Eriksson, S. & Olin, H. (2010). Nanocrystallinity in RuO2 coatings - influence of precursor and preparation temperature. Thin Solid Films, 518(14), 3615-3618
Open this publication in new window or tab >>Nanocrystallinity in RuO2 coatings - influence of precursor and preparation temperature
Show others...
2010 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, no 14, p. 3615-3618Article in journal (Refereed) Published
Abstract [en]

The effects of precursor and calcination temperature on the nano morphology of ruthenium dioxide on titanium, prepared from thermal decomposition of aqueous salt solutions were investigated. Transmission electron microscopy. X-ray diffraction, gas porosimetry and cyclic voltammetry showed that lower calcination temperature yielded smaller crystallites. The crystallites were between 6 and 22 nm in diameter. When using ruthenium nitrosyl nitrate the firing temperature had a large impact on the grain size, but for chloride there was only a minor effect in the temperature range 350-550 degrees C.

Keywords
Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-8725 (URN)10.1016/j.tsf.2009.09.065 (DOI)000278064600004 ()2-s2.0-77950543416 (Scopus ID)
Available from: 2009-03-19 Created: 2009-03-19 Last updated: 2017-12-13Bibliographically approved
Malmgren, C. (2009). Nanoscaled Structures in Ruthenium Dioxide Coatings. (Licentiate dissertation). Sundsvall: Mid Sweden University
Open this publication in new window or tab >>Nanoscaled Structures in Ruthenium Dioxide Coatings
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

An essential ingredient in the generation of environmentally compatible pulp bleaching chemicals is sodium chlorate. Chlorate is produced in electrochemical cells, where the electrodes are the key components. In Sweden the so-called DSA !R electrodes with catalytic coatings have been produced for more than 35 years. The production of chlorate uses a large amount of electric energy, and a decrease of just five percent of this consumption would, globally, decrease the consumption of electrical energy corresponding to half a nuclear power reactor. The aim of this project is to improve the electrode design on the nanoscale to decrease the energy consumption. The success of the DSA!R depends on the large catalytic area of the coating, however, little is known about the actual structure at the nanometer level. To increase the understanding of the nanostructure of these coatings, we used a number of methods, including atomic force microscopy, transmission electron microscopy, X-ray diffraction, porosimetry, and voltammetric charge. We found that the entire coating is built up of loosely packed rutile mono-crystalline 20 − 30 nm sized grains. The small grain sizes give a the large area, and consequently, lower cell-voltage and reduced energy consumption. A method to control the grain size would thus be a way to control the electrode efficiency. To alter the catalytically active area, we made changes in the coating process parameters. We found a dependency of the crystal-grain sizes on the choice of ruthenium precursor and processing temperature. The use of ruthenium nitrosyl nitrate resulted in smaller grains than ruthenium chloride and lowering the temperature tended to favour smaller grains. A more radical way would be to create a totally different type of electrode, manufactured in another way than using the 1965 DSA !R recipe. Such new types of electrodes based on, for example, nanowires or nanoimprint lithography, are discussed as future directions.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2009
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 36
Keywords
Bleaching chemicals, sodium chlorate, ruthenium dioxide, electrodes, crystallites, nanowires, microscopy, diffraction, electrocatalytic area, reduced energy consumption
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-8728 (URN)978-91-86073-33-6 (ISBN)
Presentation
(English)
Supervisors
Available from: 2009-03-19 Created: 2009-03-19 Last updated: 2013-11-01Bibliographically approved
Malmgren, C., Olin, H., Bäckström, J., Cornell, A., Hummelgård, M. & Eriksson, S. (2008). Behavioural effects of production parameters on DSA®.: . In: 59:th Annual Meeting of the International Society of Electrochemistry, Sevilla, Spain, 7-12 September 2008..
Open this publication in new window or tab >>Behavioural effects of production parameters on DSA®.:
Show others...
2008 (English)In: 59:th Annual Meeting of the International Society of Electrochemistry, Sevilla, Spain, 7-12 September 2008., 2008Conference paper, Published paper (Other academic)
Keywords
nanoteknik nanotechnology
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-6502 (URN)5311 (Local ID)5311 (Archive number)5311 (OAI)
Available from: 2009-03-19 Created: 2009-03-19 Last updated: 2013-08-23Bibliographically approved

Search in DiVA

Show all publications