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Magnetic particle trace


RISE has developed a high-resolution sensor system to follow the position and orientation of a magnetic marker in three dimensions. This sensor system can find several applications in research and industry. The system can be tailored and optimized for the customer's needs.

Small scale fluidized bed with particle tracking sensors at RISE.

Until now, the system has been used in energy research in the studes of fluidized beds, but there are additional uses in, for example, the pharmaceutical industry. Even flows in industrial processes in general can be relevant to evaluate with this technology. Partner of RISE during the development of this system has been Chalmers University of Technology (Department of Energy Technology), studying optimization of combustion processes of biofuels, and more. The technology is ripe to move on to research environments on a larger scale.

Brief description of the technique

The magnetic field from a permanent magnet can be described mathematically. By measuring this field with at least two different fixed sensor modules, the position and orientation of the magnetic cursor in comparison to the sensor modules can be calculated.

The technology is suitable for applications where the cursor can be up to 1 meter from the nearest sensor module, and where surrounding metallic objects are nonmagnetic (aluminum, stainless steel, brass, etc.).

Advantages of the system are that the cursor is passive and robust (no battery or electronics), and that it is insensitive to electrically conductive material between magnet and sensor (water, metal, etc.) - unlike systems that rely on radio transmission.

Application example:

Analysis of fluidized bed

RISE has together with Chalmers Energy Technology, developed technology for high-resolution 3D tracking of a particle in fluidized beds, Magnetic Particle Tracking (MPT).

Left: Fluidized bed ”S13” at Chalmers, utilized to analyze combustion and energy storage systems. App. 3 m tall, 1X0.5 m in cross section. Right: A network of sensitive magnetic sensors from RISE stream position data to the user PC.

Fluidized beds are used in combustion and gasification at, for example, heating plants and biogas plants, but also for synthesis of organic compounds, polymerization, pyrolysis och drying.

A fluidized bed consists of a vast amount of particles, often sand or similar. Air currents from below set the particles in motion and give liquid properties to the mass, enabling motion in the vertical direction.

The ability of fluidized test beds to efficiently convert renewable fuels such as biomass makes it an important factor in the future energy system. This ingenious method of mixing large quantities of heavy material paves the way for large-scale production of renewable heat and power, as well as CO2-neutral biofuels for the transport sector. The technology also prevents energy losses by evenly distributing the particles.

Position plot of a magnetic particle during a couple of minutes of its motion in fluidized bed "S13".

To verify theoretical models, miniaturized fluidized beds with bronze powder are used that are fluidized at room temperature by compressed air from below. These test beds are very effective tools for studying fuel mixing, by using highly accurate diagnostic methods.

By monitoring the movement of the cursor in the fluidized bed for a long time, statistics can be obtained on its movement patterns. Resolution became approx. +/- 3 mm in this project.

Publications with RISE MPT technology

  • Magnetic tracer-particle tracking in a fluid dynamically down-scaled bubbling fluidized bed; Erik Sette, David Pallarès, Filip Johnsson, Fredrik Ahrentorp, Anders Ericsson, Christer Johansson; Fuel Processing Technology, 2015 138, 368-377,
  • Magnetic tracking of a fuel particle in a fluid-dynamically down-scaled fluidized bed; Anna Köhler, David Pallarès, and Filip Johnsson; Fuel Processing Technology, 2017, 162 (147-156),
  • Experimental characterization of axial fuel mixing in fluidized beds by magnetic particle tracking; Anna Köhler, Alexander Rasch, David Pallarès, and Filip Johnsson; Powder Technology, 2017, 316 (492-499),
  • Modeling Axial Mixing of Fuel Particles in the Dense Region of a Fluidized Bed; Anna Köhler, David Pallarès, and Filip Johnsson; Energy & Fuels 2020 34 (3), 3294-3304, DOI: 10.1021/acs.energyfuels.9b04194
  • Determination of the Apparent Viscosity of Dense Gas-Solids Emulsion by Magnetic Particle Tracking; Anna Köhler, David Pallarès and Filip Johnsson; 23rd International Conference on Fluidized Bed Conversion, Seoul, Korea, 2018
  • Rheological effects of the gas-fluidized bed emulsion on falling and rising spheres; Anna Köhler, Diana Carolina Guío-Pérez, Anna Prati, Michele Larcher, David Pallarès; Submitted to Powder Technology.


Project name





Västra Götaland Region

RISE role in project


Project start


2 år

Total budget



Chalmers Tekniska Högskola

Project members

Supports the UN sustainability goals

9. Industry, innovation and infrastructure
11. Sustainable cities and communities
13. Climate action
Fredrik Ahrentorp

Contact person

Fredrik Ahrentorp


+46 10 228 41 49

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Christian Jonasson

Contact person

Christian Jonasson

Senior scientist

+46 10 228 41 53

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