Once in a while, it would be nice to have motion without magnetic fields. Anything with a compass, for instance. Maybe you also want to drive a little needle, or unlatch a door, or… whatever.
Camera lenses have had ultrasonic motors in 'em for years. I believe it’s a ring of piezoelectric material, but haven’t looked into it in much detail.
Newscale makes some totally wild little motors that use a piezoelectric twisting effect to “hula-hoop” a shaft around.
Are there other offerings in this space? How would a hobbyist get their hands on them? I feel like SFE could help here…
Since a fair amount of current runs through such a wire, there is still a magnetic field emanating from it. Weak perhaps, but still there. If that is a problem is up for experimentation.