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Emulsion droplets in a MR fluid form chains in response to a magnetic field. Researchers test properties of MR chains by gripping streptavidin-coated polystyrene tethers with optical tweezers.
Paramagnetic particles in a fluid are in disorder, but when a field is applied the particles line up into chains.
Co. developing MR fluids for earthquake protection has been developing MR fluid-based shock absorbers to help damp vibrations in seats of off-road vehicles & 18-wheel trucks. The devices mean riders can enjoy soft suspensions while driving on rough roads. But in town, where the roads are smooth, more damping is needed to keep shock absorbers from bouncing uncontrollably.
The MR material in a seismic damping device normally exists as a liquid. The device contains sensors that measure the response of the building to an earthquake & send a magnetic signal to adjust the consistency of the material. This type of damper is known as a semiactive device, an attractive avenue for engineering research since these methods have lower energy requirements than active devices yet higher controllability than passive ones
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