Would such springs lose magnetism after a while, or do they remain permanent?
I'm guessing their magnetism will be worn down by use (they're standard magnetized permamagnets), but it will happen over years in normal circumstances. The time depends on heat, currents (should be minimal) and opposing magnetic forces (relatively small here). Also impacts.
That is so cool. I can only imagine what awesome things people will use this for.
Immediately coming to mind: possible limited slip differential with electronically variable ratios
I have a pair of magnetic finger implants. Afters seeing how detailed their printing was, my first thought was using metal as a medium to send secret messages. A magnetic brail if you will.
So how long until these lose strength, or worse, the patterning altogether?
The FAQ claims they will loose about 1% of their strength every 100 years.