Department of Physics

Complex Materials


X-ray tomography laboratory

Xradia nanoCT and microCT devices.
Xradia Multiscale X-ray tomographic facility. A microtomograph (right) and a nanotomograph capable of 50 nm resolution (left).

The primary research facility within the X-ray Tomography Laboratory includes three tomographic scanners including two microtomographs and a nanotomograph. Together, these devices are capable of non-intrusive three-dimensional imaging of the internal structure of heterogeneous materials with resolution ranging from 40 μm up to 50 nm. The laboratory is equipped with comprehensive set of instruments for sample preparation and manipulation. The laboratory is also equipped with specific devices for measuring various mechanical and transport properties of materials. The entire facility has high utilization rate in basic and applied research related e.g. to development of novel organic materials, and to analysis of structural and transport properties of complex materials such as composites and bentonite clay.

More information »


  • Group members »
    • Markku Kataja, professor
    • Jussi Timonen, professor emeritus
    • Jussi Virkajärvi, postdoctoral researcher
    • Arttu Miettinen, postdoctoral researcher
    • Keijo Mattila, postdoctoral researcher
    • Pekka Kekäläinen, senior researcher
    • Topi Kähärä, postdoctoral researcher
    • Tuomas Puurtinen, postdoctoral researcher
    • Axel Ekman, postdoctoral researcher (abroad)
    • Joni Parkkonen, laboratory engineer
    • Vesa Aho, doctoral student
    • Tero Harjupatana, doctoral student
    • Timo Riikilä, doctoral student
    • Roope Lehto, doctoral student
    • Tuomas Sormunen, MSc student

    Previous years

  • Recent research
    • Time-resolved X-ray microtomographic measurement of water transport in wood-fibre reinforced composite material »

      Many materials are prone to absorb moisture from the environment. Moisture absorption may lead to degradation of the properties of the material. We have developed a method for direct non-intrusive measurement of local moisture content inside a material sample. The method is based on X-ray microtomography, digital image correlation and image analysis, and it has been applied to study axial transport of water in a cylindrical polylactic acid/birch pulp composite material sample with one end exposed to water. The method seems to give plausible estimates of water content profiles inside the cylindrical sample. The results may be used, e.g., in developing and validating models of moisture transport in biocomposites.

      [-] A. Miettinen, T. Harjupatana, M. Kataja, S. Fortino, K. Immonen, Time-resolved X-ray microtomographic measurement of water transport in wood fibre reinforced composite material, IOP Conference Series: Materials Science and Engineering 139 (2016), doi:10.1088/1757-899X/139/1/012037.

      Determination of axial water concentration profile using X-ray tomographic techniques.
      Sample assembly for determination of axial water concentration profile (left), 3D visualization of water content in the sample (middle), and measured water content profiles in the sample at various wetting times, obtained using X-ray tomographic techniques.
    • Discrete-element model for glacier dynamics »

      Global warming is one of the greatest threats that mankind has to face in the beginning of this century. Related to this is the incontrovertible mass loss of glacier ice in polar regions. Understanding the behaviour of large ice masses is thus crucial for estimating, and perhaps hindering the propagation of mass loss. In order to avoid shortcomings of continuum models, traditionally used to study glacier dynamics, a new discrete element model (DEM) for viscoelastic materials with fracture is developed [1]. In DEM models, material is comprised of a large number of particles that are bound together with interaction potentials e.g. springs or beams. Fracture and fragmentation is introduced through a breaking threshold of an interaction. With proper setting of properties of the particles themselves and the interaction potentials between them, the material can be made to realise a wide variety of elastic, plastic and viscoelastic behaviour.

      [1] T. Riikilä, Discrete Element Model for Viscoelastic Materials with Brittle Fracture: Applications on Glacier Dynamics, Department of Physics, University of Jyväskylä, Research Report 2/2017 (Doctoral thesis).


    • Multiscale modelling of heterogeneous complex fluids »

      We develop a multiscale modeling scheme for numerical studies of complex fluids composed of immiscible phases, and characterized by distinct spatial and temporal scales associated with the observable macroscopic flow behaviour and the mesoscopic phenomena related to underlying heterogeneities. Practical examples of this type heterogenous complex fluids include e.g. liquid-particle suspensions, colloids, aerosols and bubbly flows. The multiscale approach is based on concurrent coupling of a macroscale continuum model with mesoscale quasicontinuum simulations used to find the macroscale stress tensor. In particular, the mesoscale simulations either replace completely the rheological macroscale stress tensor modeling or are used to determine locally the material parameters of the assumed rheological model. The approach also aims in reducing the simulation time and simplifying the mesoscale simulation set-up. These are obtained by affecting the model coupling by choosing suitable frame of references for the mesoscale simulations and by applying sparse sampling simulation grids and interpolation of the material parameters whenever possible. The feasibility of the approach has been studied by solving flow of a wet foam in one-dimensional and in two-dimensional channel flows, by utilising DySMaL foam model in the mesoscale simulations. The method in general is potentially useful for solving flows of complex fluids for which the observable macroscopic properties may be strongly affected by their heterogeneous mesoscopic scale structure.

      Multiscale modeling setup
      Schematic illustration of multiscale modeling set-up. Separate mesoscale simulations are attached to a selected set of macroscale points (blue points). Macroscale simulation provides velocity and strain rate tensor (v, D) to initialize the mesoscale simulation which returns the stress tensor (s) to the macroscale solver (left). A 2D realization of foam for mesoscale simulation by DySMaL (right).
    • Shear rheology of two-dimensional wet foam »

      Shear rheology of two-dimensional wet foam was investigated with the DySMaL simulation model which features dynamically deformable bubbles in a wet foam context. It was found that the rheological behavior of the model at low shear rates is subject to a scaling law involving the bubble size, surface tension and the viscosity of the carrier fluid. This is consistent with experimental data and soft glassy rheological models for such systems. At high shear rates the model predicts a dynamic phase transition to a turbulent flow pattern in which the effective viscosity of the foam changes rapidly. This phase transition can be linked to changes in the average bubble deformation and nematic order of the system.
      Shear rheology
      Shear stress versus shear rate with different simulation parameters (left). The same data in dimensionless units (right). Four distinct flow regimes (A-D) can be identified from the data.
    • Swelling of bentonite clay »

      Compacted bentonite clay is planned to be used as a buffer material between high level radioactive waste canisters and the bedrock in many deep geological nuclear waste repository concepts. High swelling capability and low hydraulic permeability of the bentonite are meant to protect the canisters against rock movements and groundwater seepage. However, material modeling is needed for long-term safety evaluations of the buffer and the repository concepts. The hydromechanical behavior of the bentonite is still not fully understood, and hence detailed experimental data is needed to develop and validate the models. To this end, non-destructive methods based on X-ray imaging and tomography have been developed and successfully used to measure the deformation and water transport in bentonite samples during wetting experiments. Recently, one-dimensional free swelling of MX80 bentonite has been studied using an X-ray imaging method. An extensive set of experiments are completed, see Figures below. The method was significantly improved during 2016 by developing an advanced beam hardening correction which takes into account the angular and temporal variations in the X-ray energy spectrum.

      Sksycan for bentonite research 2017
      A SkyScan 1172 X-ray microtomographic device and a sample holder (photo, schematic cross-section and X-ray image) used in bentonite free swelling experiments.

      Bentonite experiment results 2017
      An image sequence showing the time development of the axial distribution of the bentonite and water contents during the free swelling. The last image also contains validation data measured gravimetrically from the sliced sample.
    • Fibre staining methods for contrast enhancement in X-ray nano-CT imaging »

      X-ray nanotomography has been utilized in the study of pulp fibre bonds due to its non-invasiveness and high spatial resolution in samples of magnitudes in the micrometer range. Cellulose fibres have very low X-ray absorption owing to their lack of heavy elements and low density. This poses a challenge for the imaging process, since X-ray transmittance of the fibre bond sample is very close to that of the background, resulting in long exposure times and consequently extending the total imaging time to days in order to distinguish details in the bond area. Several staining materials and methods were examined in order to increase the contrast between the sample and the background. Phosphotungstic acid (PTA) provided the highest contrast, increasing the absorption of the samples up to 40 % in highly concentrated solutions. As a result, imaging time can be considerably reduced without impairing the resolution in the process.

      PTA staining for nanotomography
      Reconstruction slices of unstained (top) and PTA stained (bottom) fibre bonds, normalized to equal grey values in the background. Although the imaging time is reduced by a factor of 3 with respect to the unstained sample, a higher contrast is yielded in the PTA stained fibre bond.
    • Lattice-Boltzmann flow simulation »


    Previous research topics

  • Publications
    • Publications of 2016 »

      Mattila, K., Puurtinen, T., Hyväluoma, J., Surmas, R., Myllys, M., Turpeinen, T., . . . Timonen, J. (2016). A prospect for computing in porous materials research: Very large fluid flow simulations. Journal of Computational Science, 12 (January), 62-76. doi:10.1016/j.jocs.2015.11.013

      Miettinen, A. (2016). Characterization of three-dimensional microstructure of composite materials by X-ray tomography. Jyväskylä, Finland: University of Jyväskylä. Research report / Department of Physics, University of Jyväskylä, 2016, 1. Retrieved from Open access

      Song, X., Moilanen, P., Zhao, Z., Ta, D., Pirhonen, J., Salmi, A., . . . Wang, W. (2016). Coded excitation speeds up the detection of the fundamental flexural guided wave in coated tubes. AIP Advances, 6 (9), 095001. doi:10.1063/1.4962400 Open access

      Aho, V., Mattila, K., Kühn, T., Kekäläinen, P., Pulkkinen, O., Minussi, R. B., . . . , & Timonen, J. (2016). Diffusion through thin membranes: Modeling across scales. Physical Review E, 93 (4), 043309. doi:10.1103/PhysRevE.93.043309 Open access

      Kuva, J., Voutilainen, M., Kekäläinen, P., Siitari-Kauppi, M., Sammaljärvi, J., Timonen, J., & Koskinen, L. (2016). Gas Phase Measurements of Matrix Diffusion in Rock Samples from Olkiluoto Bedrock, Finland. Transport in Porous Media, 115 (1), 1-20. doi:10.1007/s11242-016-0748-1

      Myllys, M., Ruokolainen, V., Aho, V., Smith, E. A., Hakanen, S., Peri, P., . . . Vihinen-Ranta, M. (2016). Herpes simplex virus 1 induces egress channels through marginalized host chromatin. Scientific Reports, 6, 28844. doi:10.1038/srep28844 Open access

      Philippi, P. C., Siebert, D. N., Hegele, L. A., Jr., & Mattila, K. (2016). High-order lattice-Boltzmann. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 38 (5), 1401-1419. doi:10.1007/s40430-015-0441-2

      Penttilä, H., Gorelov, D., Elomaa, V.-V., Eronen, T., Hager, U., Hakala, J., . . . Äystö, J. (2016). Independent isotopic yields in 25 MeV and 50 MeV proton-induced fission of natU. European Physical Journal A, 52 (4), 104. doi:10.1140/epja/i2016-16104-4 Open access

      Puurtinen, T., & Maasilta, I. (2016). Low temperature heat capacity of phononic crystal membranes. AIP Advances, 6 (12), 121902. doi:10.1063/1.4968619 Open access

      Puurtinen, T., & Maasilta, I. (2016). Low-Temperature Coherent Thermal Conduction in Thin Phononic Crystal Membranes. Crystals, 6 (6), 72. doi:10.3390/cryst6060072 Open access

      Hirvonen, J., Myllys, M., & Kallio, P. (2016). Method for 3D fibre reconstruction on a microrobotic platform. Journal of Microscopy, 263 (1), 20-33. doi:10.1111/jmi.12370

      Tallinen, T., Chung, J. Y., Rousseau, F., Girard, N., Lefèvre, J., & Mahadevan, L. (2016). On the growth and form of cortical convolutions. Nature Physics, 12 (6), 588-593. doi:10.1038/nphys3632

      Hokkanen, M., Lautala, S., Shao, D., Turpeinen, T., Koivistoinen, J., & Ahlskog, M. (2016). On-chip purification via liquid immersion of arc-discharge synthesized multiwalled carbon nanotubes. Applied Physics A: materials science & processing, 122 (7), 634. doi:10.1007/s00339-016-0154-0 Open access

      Maasilta, I., Puurtinen, T., Tian, Y., & Geng, Z. (2016). Phononic Thermal Conduction Engineering for Bolometers : From Phononic Crystals to Radial Casimir Limit. Journal of Low Temperature Physics, 184 (1), 211-216. doi:10.1007/s10909-015-1372-0

      Al-Qararah, A. M., Ekman, A., Hjelt, T., Kiiskinen, H., Timonen, J., & Ketoja, J. A. (2016). Porous structure of fibre networks formed by a foaming process : a comparative study of different characterization techniques. Journal of Microscopy, 264 (1), 88-101. doi:10.1111/jmi.12420

      Sippola, M., Immonen, K., Miettinen, A., Laukkanen, A., Andesson, T., Peltola, H., . . . , & Holmberg, K. (2016). Predicting stiffness and strength of birch pulp : polylactic acid composites. Journal of Composite Materials, 50 (18), 2549-2563. doi:10.1177/0021998315608431 Open access

      Mäntylä, E., Salokas, K., Oittinen, M., Aho, V., Mäntysaari, P., Palmujoki, L., . . . Vihinen-Ranta, M. (2016). Promoter-Targeted Histone Acetylation of Chromatinized Parvoviral Genome Is Essential for the Progress of Infection. Journal of Virology, 90 (8), 4059-4066. doi:10.1128/JVI.03160-15 Open access

      Gros, M. A. L., Clowney, E. J., Magklara, A., Yen, A., Markenscoff-Papadimitriou, E., Colquitt, B., . . . Larabell, C. A. (2016). Soft X-Ray Tomography Reveals Gradual Chromatin Compaction and Reorganization during Neurogenesis In Vivo. Cell Reports, 17 (8), 2125-2136. doi:10.1016/j.celrep.2016.10.060 Open access

      Ekman, A. (2016). The effect of steric hindrance on the packing of elongated objects. Jyväskylä, Finland: University of Jyväskylä. Research report / Department of Physics, University of Jyväskylä, 2016, 3. Retrieved from Open access

      Miettinen, A., Harjupatana, T., Kataja, M., Fortino, S., & Immonen, K. (2016). Time-resolved X-ray microtomographic measurement of water transport in wood-fibre reinforced composite material. In B. Madsen, A. Biel, Y. Kusano, H. Lilholt, L. P. Mikkelsen, L. Mishnaevsky, Jr., & B. F. Sørensen (Eds.), 37th Risø International Symposium on Materials Science (pp. 012037). IOP Conference Series : Materials Science and Engineering, 139 (1). Institute of Physics Publishing Ltd.. doi:10.1088/1757-899X/139/1/012037 Open access

      Hajlane, A., Miettinen, A., Madsen, B., Beauson, J., & Joffe, R. (2016). Use of micro-tomography for validation of method to identify interfacial shear strength from tensile tests of short regenerated cellulose fibre composites. In B. Madsen, A. Biel, Y. Kusano, H. Lilholt, L. P. Mikkelsen, L. Mishnaevsky, Jr., & B. F. Sørensen (Eds.), 37th Risø International Symposium on Materials Science (pp. 012021). IOP Conference Series : Materials Science and Engineering, 139 (1). Institute of Physics Publishing Ltd.. doi:10.1088/1757-899X/139/1/012021 Open access

    • Full list of publications »
  • Topics for thesis work »

    The Complex Materials research group offers opportunities for thesis work (BSc, research training, Master's thesis) with wide variety of possible topics. The topics include various combinations of theoretical work, programming, numerical simulations, and practical experiments in laboratories. Some topics are listed below, but you can also suggest your own topic.

    • X-ray tomography
      Design and application of 3D printed resolution targets
      Characterization of water transport in composite material using X-ray tomography
      Detection of X-rays
      Calibration of tomographic measurements
      Energy sensitive tomography
      Iterative reconstruction algorithms
      Interaction between X-rays and matter
      X-ray sources
      Phase retrieval methods for phase-contrast tomography
    • Image analysis
      Implementation and testing of new ring artefact correction method for tomographic images
      Simple methods for removal of movement artefacts in tomographic images
      Semi-automatic beam hardening correction
      Noise reduction algorithms: non-local means, TV, ...
      Neural network segmentation for large 3- and 4-dimensional images
      Implementation of regularized multiresolution 3D image correlation algorithm
    • Material properties
      Lattice-Boltzmann simulation and its applications
      Fibrous materials and contacts between fibres
      Modelling deformations of materials
      Ultrasound techniques for material characterization
      Development of laboratory exercise related to flow measurements and simulations