It's interesting to see that you're physically moving the magnets towards and away from the ferrofluid. Did you investigate electrically switchable permanent ma

It's interesting to see that you're physically moving the magnets towards and away from the ferrofluid. Did you investigate electrically switchable permanent magnets? e.g.: http://www.eclipsemagnetics.com/media/wysiwyg/datasheets/lifting_and_handling/optimag80e_datasheet_v4.pdf http://www.eclipsemagnetics.com/media/wysiwyg/datasheets/lif... I know very little about them, other than that they're cool. The ones in that datasheet start about at about 2kg, so I don't know if you can get them small enough for your purposes.