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Shim on a chip - arbitrary field profiles using superparamagnetic particles

creating arbitrary field profiles using superparamagnetic particles 

NMR systems are widely used in chemical analysis, medical diagnostics and flow measurements. With the use of permanent magnets NMR sensors can become cheaper and much smaller, however permanent magnets do not reach the needed homogeneity for NMR measurements.

 (left: Schematic view of the cuboid configuration right: Magnetic field strength as a function of the location along the x axis)

Common ways to improve the field homogeneity of magnet configurations are electric shimming - solenoid coils, planar coils or striplines are generating a field to counteract against the inhomogeneities of the magnets. This technique is energy consuming and limited due to its needed space.


A new approach is the use of superparamagnetic particles. Aim of this research is to characterize, how superparamagnetic particles can be used to change magnetic field profiles.

Superparamagnetic magnetite nanoparticles are mixed with the UV-sensitive epoxy SU-8 to obtain a magnetic composite [1]

Your research questions could be:

  • How to bind those particles?
  • How does the amount of particles and the layer thickness have influence on the magnetic field?
  • Which structures can be used to compensate field inhomogeneities?

You will start with a small literature research to see what has been done in this field. You could simulate how those particle containing layers change the magnetic field, but you don’t have to. You will work in the lab to fabricate different mixtures. A huge magnet will be the base for your experiments. After creating different samples we can measure the change of the magnetic field with a Teslameter. The project is really open, bring in your own ideas and start your experimental work!


More information can be obtained from Yannick Klein (


  1. M.Suter, Sensors and Actuators B: Chemical Volume 156, Issue 1, 10 August 2011, Pages 433-443