Researchers have been chasing the grail of self-healing circuitry for years, but the best solutions so far employed chemical reactions that had to be triggered from the outside and took hours or even days to repair a single damaged connection.
Bandodkar and Wang wanted something simple, cheap and fast. What they found was magnets.
In Wang's nanobioelectronics lab at UCSD, they ground up some inexpensive neodymium magnets into microscopic particles, then mixed the pulverized magnets with graphite and solvents to create an electronic ink. They printed a simple battery with the magnetic ink and put it to the test. The results were remarkable.
The magnetic circuits could autonomously heal a cut as wide as 3 millimeters in just 50 milliseconds. No chemical reactions, no outside intervention, just the magical attraction of magnets. Bandodkar and Wang repeated the tests, severing the circuit again and again at the same location, but it always healed itself.
"These strong magnetic properties last for decades and decades," said Bandodkar. "The self-healing process could last for a lifetime."
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The two researchers' real interest is in implantable medical devices. They see their self-healing circuits being used to print next generation pacemakers and internal diagnostic tools that never have to be removed or repaired. But first they'll have to test how the human body responds to these new types of magnetic materials.
Bandodkar also recognizes the potential trouble of a magnetically charged circuit coming into contact with metal or another electromagnetic field. He's exploring a cheap fix involving a paint that shields circuitry from electromagnetic interference.
For his next magic trick, Bandodkar is experimenting with methods that would not only reconnect a severed circuit, but erase any trace of the damage.
"We want to see how we can make the connection permanent again," said Bandodkar, now a post-doc at Northwestern University. "We have to incorporate some sort of chemistry so that once the magnet comes together, the chemical reaction takes it back to its initial state. No crack or scar at all."
Watch the video below of the battery healing.