A type of motor used to move the access arm of a disk drive in very small increments. Like the voice coil of a speaker, the amount of current determines the amount of movement. Voice coils ...

the “Magnetic Fluid” in that Magnetic Fluid Driver really is "an oil-type liquid filled with magnetic particles that is injected into the space between the driver magnet and voice coil", but ...

[TheBackyardScientist] decided to build a machine to create the gas rings, and it’s quite interesting to see them go through several iterations before settling on a voice coil based poppet valve ...