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  • 1.
    Ahrentorp, F.
    et al.
    RISE, Swedish ICT, Acreo.
    Astalan, A. P.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Blomgren, J.
    RISE, Swedish ICT, Acreo.
    Qi, B.
    Thompson Mefford, O.
    Yan, M.
    Courtois, J.
    Berret, J. F.
    Fresnais, J.
    Sandre, O.
    Dutz, S.
    Muller, R.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Sensitive High Frequency AC Suceptometry in Magnetic Nanoparticle Applications2010In: AIP Conference Proceedings, Vol. 1311, p. 213-23Article in journal (Refereed)
  • 2.
    Ahrentorp, Fredrik
    et al.
    RISE, Swedish ICT, Acreo.
    Astalan, Andrea
    RISE, Swedish ICT, Acreo.
    Blomgren, Jakob
    RISE, Swedish ICT, Acreo.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Wetterskog, Erik
    Uppsala University, Sweden.
    Svedlindh, Peter
    Uppsala University, Sweden.
    Lak, Aidin
    Technical University of Braunschweig, Germany.
    Ludwig, Frank
    Technical University of Braunschweig, Germany.
    van Ijzendoorn, Leo J.
    Eindhoven University of Technology, The Netherlands.
    Westphal, Fritz
    Micromod Partikeltechnologie GmbH, Germany.
    Gruttner, Cordula
    Micromod Partikeltechnologie GmbH, Germany.
    Gehrke, Nicole
    nanoPET Pharma GmbH, Germany.
    Gustafsson, Stefan
    Chalmers University of Technology, Sweden.
    Olsson, Eva
    Chalmers University of Technology, Sweden.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Effective particle magnetic moment of multi-core particles2015In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 380, p. 221-226Article in journal (Refereed)
    Abstract [en]

    In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy(TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems – BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm – and one single-core particle system – SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.

  • 3.
    Ahrentorp, Fredrik
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sarwe, Anna
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sepehri, Sobhan
    Chalmers University of Technology, Sweden.
    Eriksson, Emil
    Chalmers University of Technology, Sweden.
    Kalaboukhov, Alexei
    Chalmers University of Technology, Sweden.
    Jesorka, Aldo
    Chalmers University of Technology, Sweden.
    Winkler, Dag
    Chalmers University of Technology, Sweden.
    Schneiderman, Justin F.
    University of Gothenburg, Sweden.
    Nilsson, Mats
    Stockholm University, Sweden.
    Albert, Jan
    Karolinska University Hospital, Sweden; Karolinska Institute, Sweden.
    de la Torre, Theresa Z. G.
    Uppsala University, Sweden.
    Strømme, Maria
    Uppsala University, Sweden.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils2017In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, p. 14-18Article in journal (Refereed)
    Abstract [en]

    We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  • 4.
    Baresel, Christian
    et al.
    IVL Swedish Environmental Research Institute AB, Sweden.
    Schaller, Vincent
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Bordes, Romain
    Chalmers University of Technology, Sweden.
    Chauhan, Vinay
    Chalmers University of Technology, Sweden.
    Sugunan, Abhilash
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Sommertune, Jens
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Welling, Sebastian
    IVL Swedish Environmental Research Institute AB, Sweden.
    Functionalized magnetic particles for water treatment2019In: Heliyon, ISSN 2405-8440, Vol. 5, no 8, article id e02325Article in journal (Refereed)
    Abstract [en]

    In this study, we have taken the concept of water treatment by functionalized magnetic particles one step forward by integrating the technology into a complete proof of concept, which included the preparation of surface modified beads, their use as highly selective absorbents for heavy metals ions (Zinc, Nickel), and their performance in terms of magnetic separation. The separation characteristics were studied both through experiments and by simulations. The data gathered from these experimental works enabled the elaboration of various scenarios for Life Cycle Analysis (LCA). The LCA showed that the environmental impact of the system is highly dependent on the recovery rate of the magnetic particles. The absolute impact on climate change varied significantly among the scenarios studied and the recovery rates. The results support the hypothesis that chelation specificity, magnetic separation and bead recovery should be optimized to specific targets and applications. 

  • 5.
    Blomgren, Jakob
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ahrentorp, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ilver, Dag
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Sepehri, Sobhan
    Chalmers University of Technology, Sweden.
    Kalaboukhov, Alexei
    Chalmers University of Technology, Sweden.
    Winkler, Dag
    Chalmers University of Technology, Sweden.
    de la Torre, Tereza
    Uppsala University, Sweden.
    Strømme, Maria
    Uppsala University, Sweden.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Development of a sensitive induction-based magnetic nanoparticle biodetection method2018In: Nanomaterials, ISSN 2079-4991, Vol. 8, no 11, article id 887Article in journal (Refereed)
    Abstract [en]

    We developed a novel biodetection method for influenza virus based on AC magnetic susceptibility measurement techniques (the DynoMag induction technique) together with functionalized multi-core magnetic nanoparticles. The sample consisting of an incubated mixture of magnetic nanoparticles and rolling circle amplified DNA coils is injected into a tube by a peristaltic pump. The sample is moved as a plug to the two well-balanced detection coils and the dynamic magnetic moment in each position is read over a range of excitation frequencies. The time for making a complete frequency sweep over the relaxation peak is about 5 minutes (10 Hz–10 kHz with 20 data points). The obtained standard deviation of the magnetic signal at the relaxation frequency (around 100 Hz) is equal to about 10−5 (volume susceptibility SI units), which is in the same range obtained with the DynoMag system. The limit of detection with this method is found to be in the range of 1 pM.

  • 6.
    Chakkarapani, Prabu
    et al.
    Anna University, India.
    Subbiah, Latha
    Anna University, India.
    Palanisamy, Selvamani
    Anna University, India.
    Bibiana, Arputha
    Anna University, India.
    Ahrentorp, Fredrik
    RISE, Swedish ICT, Acreo.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Encapsulation of methotrexate loaded magnetic microcapsules for magnetic drug targeting and controlled drug release2015In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 380, p. 285-294Article in journal (Refereed)
    Abstract [en]

    We report on the development and evaluation of methotrexate magnetic microcapsules (MMC) for targeted rheumatoid arthritis therapy. Methotrexate was loaded into CaCO3-PSS (poly (sodium 4-styrenesulfonate)) doped microparticles that were coated successively with poly (allylamine hydrochloride) and poly (sodium 4-styrenesulfonate) by layer-by-layer technique. Ferrofluid was incorporated between the polyelectrolyte layers. CaCO3-PSS core was etched by incubation with EDTA yielding spherical MMC. The MMC were evaluated for various physicochemical, pharmaceutical parameters and magnetic properties. Surface morphology, crystallinity, particle size, zeta potential, encapsulation efficiency, loading capacity, drug release pattern, release kinetics and AC susceptibility studies revealed spherical particles of ~3 µm size were obtained with a net zeta potential of +24.5 mV, 56% encapsulation and 18.6% drug loading capacity, 96% of cumulative drug release obeyed Hixson-Crowell model release kinetics. Drug excipient interaction, surface area, thermal and storage stability studies for the prepared MMC was also evaluated. The developed MMC offer a promising mode of targeted and sustained release drug delivery for rheumatoid arthritis therapy.

  • 7.
    Fock, Jeppe
    et al.
    DTU Technical University of Denmark, Denmark .
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Hansen, Mikkel F.
    DTU Technical University of Denmark, Denmark .
    Characterization of fine particles using optomagnetic measurements2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 13, p. 8802-8814Article in journal (Refereed)
    Abstract [en]

    The remanent magnetic moment and the hydrodynamic size are important parameters for the synthesis and applications of magnetic nanoparticles (MNPs). We present the theoretical basis for the determination of the remanent magnetic moment and the hydrodynamic size of MNPs with a narrow size distribution using optomagnetic measurements. In these, the 2nd harmonic variation of the intensity of light transmitted through an MNP suspension is measured as a function of an applied axial oscillating magnetic field. We first show how the measurements of the optomagnetic signal magnitude at a low frequency vs. magnetic field amplitude can be used to determine the MNP moment. Subsequently, we use linear response theory to describe the dynamic non-equilibrium response of the MNP suspension at low magnetic field amplitudes and derive a link between optomagnetic measurements and magnetic AC susceptibility measurements. We demonstrate the presented methodology on two samples of commercially available multi-core MNPs. The results compare well with those obtained by dynamic light scattering, AC susceptibility and vibrating sample magnetometry measurements on the same samples when the different weighting of the particle size in the techniques is taken into account. The optomagnetic technique is simple, fast and does not require prior knowledge of the concentration of MNPs and it thus has the potential to be used as a routine tool for quality control of MNPs.

  • 8.
    Jonasson, Christian
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Benselfelt, Tobias
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ilver, Dag
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Olofsson, Linda
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Utvärdering av onlinesystem för tidig varning avfekal påverkan i råvattenBaserad på interferensmoduleradflödescytometr2015Report (Other academic)
    Abstract [en]

    The aim of this project is to investigate a new method for fast detectionof fecal contamination in water resources by using E. coli as indicator bacteria. Online measurement of raw water quality is important in order toavoid outbreaks of waterborne diseases and therefor very interesting for thewater producers for society in general. The method is based on fluorescently labelled antibodies which specific binds to the indicator bacteria andan instrument was developed to count individual bacteria in a continuously sample flow. The system was designed to be more robust to match theindustrial environment to a lower cost than a conventional flow cytometer.The fluorescent markers was at first chosen in the visible region of thelight spectrum, but early tests showed a high level of interfering fluorescent background signal in this region, arising from the chlorophyll in algaeand cyanobacteria in raw water. Hence a decision was made to change themeasurement to near-infrared (NIR) wavelengths, in order to reduce thebackground signal. The change of measurement region solved the problem with background fluorescence which is an important step towards aworking product. The required adjustments of the optics in the instrumentintroduced new challenges, especially on the detector side.Field trials performed at Överby Water treatment plant in Trollhättanshowed that the instrument was working fine in the industrial environmentand connection to the raw water pipe was tested. Laboratory measurementsshowed that the instrument clearly could measure difference between rawwater samples and treated sewage water, but the estimated differences inconcentration were lower than expected.The greatest challenge with this technique is probably to achieve a sufficient sample flow through the instrument in order to get a good estimationof the E. coli concentration within reasonable time (minutes). However, itis possible to increase the throughput flow by increasing the size of the flowchannel, but this will probably lower the sensitivity of the system and this isan important trade-off for future development.The evaluation done in this project shows that the instrument has greatpotential for online measurement of E.coli content in raw water, whichmakes it suitable as an early warning system. To invest in further development can be well motivated.

  • 9.
    Jonasson, Christian
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Schaller, Vincent
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Zeng, Lunjie
    Chalmers University of Technology, Sweden.
    Olsson, Eva
    Chalmers University of Technology, Sweden.
    Frandsen, Cathrine
    DTU Technical University of Denmark, Denmark.
    Castro, Alejandra
    Solve AB, Sweden.
    Nilsson, Lars
    Solve AB, Sweden.
    Bogart, Lara
    University College London, UK.
    Southern, Paul
    University College London, UK.
    Pankhurst, Quentin
    University College London, UK.
    Morales, Puerto
    Institute of Material Science of Madrid, Spain.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Modelling the effect of different core sizes and magnetic interactions inside magnetic nanoparticles on hyperthermia performance2019In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 477, p. 198-202Article in journal (Refereed)
    Abstract [en]

    We present experimental intrinsic loss power (ILP) values, measured at an excitation frequency of 1 MHz and at relatively low field amplitudes of 3.4 to 9.9 kA/m, as a function of the mean core diameter, for selected magnetic nanoparticle (MNP). The mean core sizes ranged from ca. 8 nm to 31 nm. Transmission electron microscopy indicated that those with smaller core sizes (less than ca. 22 nm) were single-core MNPs, while those with larger core sizes (ca. 29 nm to 31 nm) were multi-core MNPs. The ILP data showed a peak at ca. 20 nm. We show here that this behaviour correlates well with the predicted ILP values obtained using either a non-interacting Debye model, or via dynamic Monte-Carlo simulations, the latter including core-core magnetic interactions for the multi-core particles. This alignment of the models is a consequence of the low field amplitudes used. We also present interesting results showing that the core-core interactions affect the ILP value differently depending on the mean core size.

  • 10.
    Jonsson, Per
    et al.
    FOI Swedish Defence Reasearch Agency, Sweden.
    Lindgren, David
    FOI Swedish Defence Reasearch Agency, Sweden.
    Asplund, Mailn
    Tekniska verken i Linköping AB, Sweden.
    Stavjklint, Helenea
    Tekniska verken i Linköping AB, Sweden.
    Magounakis, Malin
    Tekniska verken i Linköping AB, Sweden.
    Mokhlesi, Saeed
    Chalmers University of Technology, Sweden.
    Pettersson, Thomas
    Chalmers University of Technology, Sweden.
    Winquist, Fredrik
    Linköping University, Sweden.
    Eriksson, Mats
    Linköping University, Sweden.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ilver, Dag
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Strömbeck, Niclas
    Luode Consulting Oy, Sweden.
    Svenskt Vatten Utveckling Elektronisk tunga och andra onlinesensorer för detektion av föroreningar i dricksvattennätet – en utvärdering2018Report (Other academic)
    Abstract [sv]

    Projektet har utvärderat olika onlinesensorer för att upptäcka föroreningar från avloppsvatten i dricksvattennätet. Flera kommersiella sensorer kunde detektera inläckage vid koncentrationer av avloppsvatten på cirka 0,7 procent, men bäst var den nyutvecklade sensor som kallas elektronisk tunga. Den kunde med låg sannolikhet för falsklarm detektera ner till åtminstone 0,05 procent avloppsvatten. Vanliga problem som kan ge upphov till smitta via dricksvatten är gamla och läckande ledningsnät som ger tryckfall, eller felaktiga kopplingar som gör att ytvatten och avloppsvatten kan förorena dricksvattnet. Risken för inläckage av avloppsvatten ansågs i projektet vara det högst prioriterade scenariot. Med ett nätverk av sensorer i dricksvattennätet och ett effektivt övervakningssystem skulle man kunna upptäcka och lokalisera föroreningskällan och ingripa med nödvändiga åtgärder innan det förorenade vattnet når kunderna.

    Projektet utfördes av Tekniska verken i Linköping i samverkan med Totalförsvarets forskningsinstitut (FOI) och ett stort antal andra aktörer. I en referensgrupp ingick ett antal svenska dricksvattenproducenter som ställde upp viktiga kriterier för onlinesensorer i dricksvattennätet. Sensorerna ska vara billiga, robusta, driftsäkra, anpassade för driftmiljön och kräva lite underhåll. De ska inte behöva förbehandling eller reagenser och bör helst mäta direkt på det trycksatta nätet. De bör helst vara generella, det vill säga upptäcka alla typer av föroreningar, men det är ett stort mervärde om de kan klassificera typen av förorening. Den elektroniska tungan har vidareutvecklats inom Vinnovaprojektet Sensation III. Även de nya sensorerna flödescytometer och elektronisk näsa testades i projektet, liksom standardsensorer för konduktivitet, pH och kloröverskott, samt en avancerad sensor baserad på optisk absorbans. Testerna skedde i en rigg på avloppsreningsverket i Linköping under ett par månader då olika koncentrationer av avloppsvatten tillfördes. Även syntetiskt avloppsvatten och råvatten tillfördes vid några tillfällen. Två elektroniska tungor testades även vid en tryckstegringsstation respektive vid vattentornet under cirka ett år. Olika typer av signalbehandling undersöktes för att optimera larmalgoritmerna.

    Resultaten visar att det är möjligt att upptäcka inläckage av avloppsvatten i dricksvattnet med hjälp av onlinesensorer. Även standardsensorer för konduktivitet och pH kunde detektera inläckage av avloppsvatten, men bäst resultat gav den elektroniska tungan. Sensorn för optisk absorbans hade en detektionsgräns mellan den elektroniska tungan och standardsensorerna. I anläggningar med större utspädning av avloppsvattnet än i Linköping kommer sensorerna förmodligen att ha en högre detektionsgräns.

    För att det ska bli möjligt att övervaka dricksvattenkvaliteten med hjälp av onlinesensorer krävs det nära samverkan mellan sensortillverkare, dricksvattenproducenter och -distributörer, eftersom det behövs fortsatta tester och är så svårt att kravställa och bestämma prestandan för sensorerna för alla tänkbara vatten.

  • 11.
    Kumari, Monika
    et al.
    ETH Zurich, Switzerland.
    Hirt, Ann
    ETH Zurich, Switzerland.
    Uebe, Rene
    Ludwig Maximilian University of Munich, Germany; University of Bayreuth, Germany.
    Schuler, Dirk
    Ludwig Maximilian University of Munich, Germany; University of Bayreuth, Germany.
    Tompa, Eva
    University of Pannonia, Hungary.
    Mihaly Posfai, Mihaly
    University of Pannonia, Hungary.
    Lorenz, Wolfram
    ETH Zurich, Switzerland.
    Ahrentorp, Fredrik
    RISE, Swedish ICT, Acreo.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Experimental mixtures of superparamagnetic single domain magnetite with respect to Day-Dunlop plots2015In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 16, no 6, p. 1739-1752Article in journal (Refereed)
    Abstract [en]

    Day‐Dunlop plots are widely used in paleomagnetic and environmental studies as a tool to determine the magnetic domain state of magnetite, i.e., superparamagnetic (SP), stable single‐domain (SD), pseudosingle‐domain (PSD), multidomain (MD), and their mixtures. The few experimental studies that have examined hysteresis properties of SD‐SP mixtures of magnetite found that the ratios of saturation remanent magnetization to saturation magnetization and the coercivity of remanence to coercivity are low, when compared to expected theoretical mixing trends based on Langevin theory. This study reexamines Day‐Dunlop plots using experimentally controlled mixtures of SD and SP magnetite grains. End‐members include magnetotactic bacteria (MSR‐1) as the SD source, and a commercial ferrofluid or magnetotactic bacteria (ΔA12) as the SP source. Each SP‐component was added incrementally to a SD sample. Experimental results from these mixing series show that the magnetization and coercivity ratios are lower than the theoretical prediction for bulk SP magnetic size. Although steric repulsion was present between the particles, we cannot rule out interaction in the ferrofluid for higher concentrations. The SP bacteria are noninteracting as the magnetite was enclosed by an organic bilipid membrane. Our results demonstrate that the magnetization and coercivity ratios of SD‐SP mixtures can lie in the PSD range, and that an unambiguous interpretation of particle size can only be made with information about the magnetic properties of the end‐members.

  • 12.
    Ludwig, F.
    et al.
    Technische Universität Braunschweig, Germany.
    Kazakova, O.
    National Physical Laboratory, UK.
    Barquin, L. F.
    University of Cantabria, Spain.
    Fornara, A.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Trahms, L.
    Physikalisch-Technische Bundesanstalt, Germany.
    Steinhoff, U.
    Physikalisch-Technische Bundesanstalt, Germany.
    Svedlindh, P.
    Uppsala University, Sweden.
    Wetterskog, E
    Uppsala University, Sweden.
    Pankhurst, Q. A.
    University College of London, UK.
    Southern, P.
    University College of London, UK.
    Morales, P.
    University of Cantabria, Spain.
    Hansen, M. F.
    DTU Technical University of Denmark, Denmark.
    Frandsen, C.
    DTU Technical University of Denmark, Denmark.
    Olsson, E.
    Chalmers University of Technology, Sweden.
    Gustafsson, S.
    Chalmers University of Technology, Sweden.
    Gehrke, N.
    NanoPET Pharma GmbH, Germany.
    Ludtke-Buzug, K.
    University of Lübeck, Germany.
    Gruttner, C.
    Micromod Partikeltechnologie GmbH, Germany.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Magnetic, Structural, Particle Size Analysis of Single- Multi-Core Magnetic Nanoparticles2014In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 50, no 11, p. 5300204-Article in journal (Refereed)
    Abstract [en]

    We have measured and analyzed three different commercial magnetic nanoparticle systems, both multi-core and single-core in nature, with the particle (core) size ranging from 20 to 100 nm. Complementary analysis methods and same characterization techniques were carried out in different labs and the results are compared with each other. The presented results primarily focus on determining the particle size - both the hydrodynamic size and the individual magnetic core size - as well as magnetic and structural properties. The used analysis methods include transmission electron microscopy, static and dynamic magnetization measurements, and Mössbauer spectroscopy. We show that particle (hydrodynamic and core) size parameters can be determined from different analysis techniques and the individual analysis results agree reasonably well. However, in order to compare size parameters precisely determined from different methods and models, it is crucial to establish standardized analysis methods and models to extract reliable parameters from the data. 

  • 13.
    Ludwig, Frank
    et al.
    TU Braunschweig, Germany.
    Balceris, Christoph
    TU Braunschweig, Germany.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Analysis of AC Susceptibility Spectra for the Characterization of Magnetic Nanoparticles2017In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 53, no 11, article id 7898860Article in journal (Refereed)
    Abstract [en]

    Measurements of the ac susceptibility (ACS) as a function of frequency have been widely applied for the determination of structure parameters of magnetic nanoparticles (MNP). The analysis of spectra of real and imaginary parts measured on suspensions of MNP is generally based on the Debye model, extended by distributions of size parameters. Here, we compare different modifications of the Debye model with experimental data recorded on suspensions of single-core and multi-core iron-oxide nanoparticles. The applied models also depend on whether the nanoparticle's magnetic moments are thermally blocked and whether both Brownian and Néel relaxation have to be taken into account. The obtained core and hydrodynamic size parameters are compared with those from transmission electron microscopy and dynamic light scattering. Whereas structure parameters can be reliably determined for single-core nanoparticles, the interpretation of ACS spectra measured on multi-core nanoparticles is more complicated, especially regarding the contribution of particles relaxing via the Néel mechanism. Depending on the packing density and thus the interaction between cores in a particle, the effective core parameters derived from the spectrum must be interpreted with care.

  • 14.
    Ludwig, Frank
    et al.
    Technische Universität Braunschweig, Germany.
    Balceris, Christoph
    Technische Universität Braunschweig, Germany.
    Viereck, Thilo
    Technische Universität Braunschweig, Germany.
    Posth, Oliver
    Physikalisch-Technische Bundesanstalt, Germany.
    Steinhoff, Uwe
    Physikalisch-Technische Bundesanstalt, Germany.
    Gavilan, Helena
    CSIC Instituto de Ciencia de Materiales de Madrid, Spain.
    Costo, Rocio
    CSIC Instituto de Ciencia de Materiales de Madrid, Spain.
    Zeng, Lunjie
    Chalmers University of Technology, Sweden.
    Olsson, Eva
    Chalmers University of Technology, Sweden.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Size analysis of single-core magnetic nanoparticles2017In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 427, p. 19-24Article in journal (Refereed)
    Abstract [en]

    Single-core iron-oxide nanoparticles with nominal core diameters of 14 nm and 19 nm were analyzed with a variety of non-magnetic and magnetic analysis techniques, including transmission electron microscopy (TEM), dynamic light scattering (DLS), static magnetization vs. magnetic field (M-H) measurements, ac susceptibility (ACS) and magnetorelaxometry (MRX). From the experimental data, distributions of core and hydrodynamic sizes are derived. Except for TEM where a number-weighted distribution is directly obtained, models have to be applied in order to determine size distributions from the measurand. It was found that the mean core diameters determined from TEM, M-H, ACS and MRX measurements agree well although they are based on different models (Langevin function, Brownian and Néel relaxation times). Especially for the sample with large cores, particle interaction effects come into play, causing agglomerates which were detected in DLS, ACS and MRX measurements. We observed that the number and size of agglomerates can be minimized by sufficiently strong diluting the suspension.

  • 15.
    Lund, A.
    et al.
    University of Borås, Sweden.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Haagensen, D.
    Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Piezoelectric polymeric bicomponent fibers produced by melt spinning2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 126, no 2, p. 490-500Article in journal (Refereed)
    Abstract [en]

    Melt spinning of a novel piezoelectric bicomponent fiber, with poly(vinylidene fluoride) as the electroactive sheath component, has been demonstrated. An electrically conductive compound of carbon black (CB) and high density polyethylene was used as core material, working as an inner electrode. A force sensor consisting of a number of fibers embedded in a soft CB/polyolefin elastomer matrix was manufactured for characterization. The fibers showed a clear piezoelectric effect, with a voltage output (peak-to-peak) of up to 40 mV under lateral compression. This continuous all-polymer piezoelectric fiber introduces new possibilities toward minimal single fiber sensors as well as large area sensors produced in standard industrial weaving machines. Copyright © 2012 Wiley Periodicals, Inc.

  • 16.
    Lund, Anja
    et al.
    University of Borås, Sweden; Chalmers University of Technology, Sweden.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Jonasson, Christian
    Haagensen, Daniel
    Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Piezoelectric polymeric bicomponent fibers produced by melt spinning2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 126, p. 490-500Article in journal (Refereed)
    Abstract [en]

    Melt spinning of a novel piezoelectric bicomponent fiber, with poly(vinylidene fluoride) as the electroactive sheath component, has been demonstrated. An electrically conductive compound of carbon black (CB) and high density polyethylene was used as core material, working as an inner electrode. A force sensor consisting of a number of fibers embedded in a soft CB/polyolefin elastomer matrix was manufactured for characterization. The fibers showed a clear piezoelectric effect, with a voltage output (peak-to-peak) of up to 40 mV under lateral compression. This continuous all-polymer piezoelectric fiber introduces new possibilities toward minimal single fiber sensors as well as large area sensors produced in standard industrial weaving machines.

  • 17.
    Nilsson, Erik
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Lund, Anja
    Chalmers University of Technology, Sweden.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Poling and characterization of piezoelectric polymer fibers for use in textile sensors2013In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 201, p. 477-486Article in journal (Refereed)
    Abstract [en]

    This study reports on the poling and characteristics of a melt-spun piezoelectric bicomponent fiber with poly(vinylidene fluoride) (PVDF) as its sheath component and a conductive composite with carbon black (CB) and high density polyethylene (HDPE) as its core component. The influence of poling conditions on the piezoelectric properties of the fibers has been investigated. The poling parameters temperature, time and poling voltage have been varied and the piezoelectric effect of both contact- and corona-poled yarns have been evaluated. The results show that a high piezoelectric effect is achieved when the poling voltage is high as possible and the poling temperature is between 60° C and 120 °C. It was also shown that permanent polarization is achieved in a time as short as 2 s in corona-poled fibers. A yarn exposed to a sinusoidal axial tension of 0.07% strain (the corresponding force amplitude was 0.05 N) shows an intrinsic voltage output of 4 V. The mean power from a 25 mm length of yarn is estimated to be 15 nW. To demonstrate the fibers sensor properties, they are woven into a textile fabric from which a force sensor is manufactured and used to detect the heartbeat of a human.

  • 18. Nilsson, Erik
    et al.
    Lund, Anja
    Jonasson, Christian
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Hagström, Bengt
    Poling characterization of piezoelectric polymer fibers for use in textile sensors2013In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 201, p. 477-486Article in journal (Refereed)
  • 19.
    Prieto Astalan, A.
    et al.
    RISE, Swedish ICT, Acreo.
    Jonasson, Christian
    RISE, Swedish ICT, Acreo.
    Petersson, K.
    RISE, Swedish ICT, Acreo.
    Blomgren, J
    RISE, Swedish ICT, Acreo.
    Ilver, Dag
    RISE, Swedish ICT, Acreo.
    Krozer, A.
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Magnetic response of thermally blocked magnetic nanoparticles in a pulsed magnetic field2007In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 311, no 1, p. 166-70Article in journal (Refereed)
    Abstract [en]

    In order to detect fast changes of the Brownian relaxation time due to reaction kinetics on the surface of magnetic particles or particle-clustering processes, we have developed a method that uses pulsed magnetic fields and detects the relaxation of the magnetic response on the time scale of milliseconds. We compared measurements in the frequency domain with the time domain measurement using particle suspensions with three different median sizes. The results obtained with the two methods agreed well. Time domain determination of Brownian relaxation was then used to study the reaction kinetics of the clustering process when sodium chloride solution was added to a magnetic nanoparticle suspension.

  • 20.
    Riordan, E
    et al.
    Cardiff University, UK.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ahrentorp, Fredrik
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Margineda, D.
    Cardiff University, UK.
    Elfassi, A.
    INSA Institut National des Sciences Appliques, France.
    Michel, S.
    INSA Institut National des Sciences Appliques, France.
    Dell'ova, F.
    INSA Institut National des Sciences Appliques, France.
    Klemencic, G. M.
    Cardiff University, UK.
    Giblin, S. R.
    Cardiff University, UK.
    Design and implementation of a low temperature, inductance based high frequency alternating current susceptometer.2019In: Review of Scientific Instruments, Vol. 90, no 7Article in journal (Refereed)
    Abstract [en]

    We report on the implementation of an induction based, low temperature, high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration allow a sample magnetic moment resolution of 5 × 10−10 Am2 at 1 MHz. We discuss the design and characterization of the susceptometer and explain the calibration process. We also include some example measurements on the spin ice material CdEr2S4 and iron oxide based nanoparticles to illustrate functionality.

  • 21.
    Schanzenbach, Christoph
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ilver, Dag
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Blomgren, Jacob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Krozer, Aanatol
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ye, Lei
    Lund University, Sweden.
    Rustas, Bengt-Ove
    SLU Swedish University of Agricultural Science, Sweden.
    Preparation and characterisation of a sensing system for wireless pH measurements in vivo, in a rumen of a cow2017In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 242, p. 637-644Article in journal (Refereed)
    Abstract [en]

    We describe a sensing system that is able to measure pH in-vivo, in the rumen of a cow, in real time. The sensing principle is based on gravimetric transduction using a magnetoelastic ribbon functionalized by pH-sensitive nanobeads that is placed in the rumen where it is actuated and read-out wirelessly. We describe a generic procedure that enables one to deposit monolayers or multilayers of nano- and micro beads onto virtually any substrate. The topography of the resulting layers as well as interlayer coverages were characterised using optical microscopy and scanning profilometry. First we determined performance of the system in-vitro, in phosphate-buffered saline, in McDougall's buffer and in a rumen fluid. Thereafter we also performed in-vivo measurements. Using buffers we determined pH response in the liquids both at the fundamental frequency of the functionalised foils, and at the 1st overtone. We argue that observed frequency changes vs pH are mainly due to changes of trapped liquid when the bead layers shrink or expand as a response to changed pH. The data obtained from the pH response of magnetoelastic foils at different bead coverages was modelled by a simple two-parameter model that corroborates this assumption.

  • 22.
    Sriviriyakul, Thana
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Bogren, Sara
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Schaller, Vincent
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ahrentorp, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Lopez-Sanchez, Patricia
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Berta, Marco
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Grüttner, Cordula
    micromod Partikeltechnologie GmbH, Germany.
    Zeng, Lunjie
    Chalmers University of Technology, Sweden.
    Stading, Mats
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nanorheological studies of xanthan/water solutions using magnetic nanoparticles2019In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 473, p. 268-271Article in journal (Refereed)
    Abstract [en]

    We show results of nanorheological studies of different concentrations of xanthan (non-Newtonian fluid) in water using magnetic nanoparticles (MNPs) together with the AC susceptibility (ACS) vs frequency method. For comparison we also show the ACS response for different concentrations of glycerol in water (Newtonian fluid). The ACS response is measured, and the data is modelled using dynamic magnetic models and different viscoelastic models. We study the ACS response (in-phase and out-of-phase ACS components) at different concentrations of xanthan in water (up to 1 wt% xanthan) and with a constant concentration of MNPs. We use MNP systems that show Brownian relaxation (sensitive to changes in the environmental properties around the MNPs). ACS measurements are performed using the DynoMag system. The Brownian relaxation of the MNP system peak is shifting down in frequency and the ACS response is broadening and decreases due to changes in the viscoelastic properties around the MNPs in the xanthan solution. The viscosity and the storage moduli are determined at each excitation frequency and compared with traditional macroscopic small amplitude oscillatory shear rheological measurements. The results from the traditional rheological and nanorheological measurements correlate well at higher xanthan concentration.

  • 23.
    Wetterskog, Erik
    et al.
    Uppsala University, Sweden.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Smilgies, Detlef-M
    Cornell University, USA.
    Schaller, Vincent
    Chalmers industriteknik, Sweden.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Svedlindh, Peter
    Uppsala University, Sweden.
    Colossal Anisotropy of the Dynamic Magnetic Susceptibility in Low-Dimensional Nanocube Assemblies2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 2, p. 1403-1412Article in journal (Refereed)
    Abstract [en]

    nanocubes display a significant augmentation of the magnetic susceptibility and dissipation as compared to 0D and 2D systems. The performance of the nanocube needles is highlighted by a colossal anisotropy factor defined as the ratio of the parallel to the perpendicular magnetization components. We show that the origin of this effect cannot be ascribed to shape anisotropy in its classical sense; as such, it has no analogy in bulk magnetic materials. The temperature-dependent anisotropy factors of the in- and out-of-phase components of the magnetization have an extremely strong particle size dependence and reach values of 80 and 2500, respectively, for the largest nanocubes in this study. Aided by simulations, we ascribe the anisotropy of the magnetic susceptibility, and its strong particle-size dependence to a synergistic coupling between the dipolar interaction field and a net anisotropy field resulting from a partial texture in the 1D nanocube needles.

1 - 23 of 23
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