Switchable Surface Stiffening

Switchable Surface Stiffening.
© K. Dobberke for Fraunhofer ISC
Switchable Surface Stiffening.

In order to reversibly stiffen a Magnetorheological Fluid (MRF) having an upwardly open surface, the magnetic field generating magnetic circuit must be placed under the MRF. Without a magnetic field, the material surface is viscous and thus easily deformable. After applying the magnetic field, a solid gel is created, which retains a contour impressed into the surface. In addition, an item can be dipped in the liquid MRF. After switching on the magnetic field, the object is fixed by the stiffening of the MRF and released again after switching off.

To generate the magnetic field that stiffens the MRF in such a way, a magnetic circuit is required, which penetrates the MRF from below, but is open at the top. This is achieved by a special magnetic circuit design in which all magnetic circuit components are located below the MRF. The magnetic circuit design is supported by appropriate FEM simulations. To protect an object pressed into the MRF surface from contamination by the MRF, a protective film can also be used. This separates the MRF to outward as in a cushion (MRF cushion).


  • Composition property correlations of MRF
  • Conception and construction of MRF cushions
  • Simulation of magnetic circuits, also with permanent magnets
  • Characterization of MRF cushions


  • Development of customized MRF cushions
  • Development of special MRF for MRF cushions
  • Construction of demonstrators for MRF cushions
  • Magnetic circuit design for MRF cushions, also with permanent magnets