High Gradient Magnetic Fields in Action!

By clicking on the images a video clip will demonstrate:
[LEFT] The initial sedimentation and then upward movement of amyloplasts in an HGMF and
[CENTER] The lateral displacement of starch grains after insertion of a wedge into a uniform magnetic field. The
[RIGHT] clip demonstrates the behavior of statoliths in a Chara rhizoid in the presence and absence of a HGMF.

Sedimentation	Wedge	Chara
This picture/diagram/movie illustrates the effect of a high gradient magnetic field on sedimenting starch grains. Switchable electro magnets (N and S pole, not visible in movie) provide the magnetic field. Due to its size a B magnetic gradient forms (symbolized by the curved field lines). Sedimenting diamagnetic substances such as starch experience a repulsive force that causes upward movement. The particles sediment in the absence of the field but move upward as soon as the HGMF is switched on. The diameter of the capillary is about 0.3 mm.	This picture/diagram/movie demonstrates the effect of a high gradient magnetic field on rapidly sedimenting large starch grains. Permanent magnets (not visible) provide the magnetic field that is concentrated by the ferromagnetic wedge. The resulting magnetic gradient (symbolized by the field lines on the right) repels diamagnetic substances such as starch. The same principle applies to dense intracellular masses which move due to intracellular magnetophoresis. The diameter of the capillary is about 0.3 mm.	This movie clip shows the regular position of statolith in a Chara rhizoid. When the HGMF is switched on, the upward-directed force moves the statoliths away from the apex of the rhizoid. When the HGMF is switched off, the statoliths sediment due to the effect of gravity. Measurements of the velocity of upward and downward movement are suitable to determine the viscoelastic properties of the cytoplasm of the apical area of the rhizoid. Depolymerization or stabilization of cytoskeletal elements permits the study of effects of the cytoskeleton on statolith positioning. More Chara experiments!

See High Gradient Magnetic Fields for a more physically oriented description.

You may also be interested in visiting the High Field Magnet Laboratory at the University of Nijmegen where you can find examples of one application of HGMF's
- the levitation of biological objects such as frogs, fruits and water!