New Material Heals Like Biological Tissue to Maintain Electrical Conductivity

When you cut your finger, you don’t have a cut on your finger forever. It heals, and that’s something that even our most advanced machines can’t do. They’re dependent on us for repair and maintenance, but a team of researchers from the Integrated Soft Materials Laboratory at Carnegie Mellon University has devised a new material that can heal itself to maintain electrical conductivity even when severely damaged.

There have been many demonstrations of flexible electronics that could be used in so-called “soft robotics.” However, these materials are more vulnerable to damage than cold, unyielding metal. The newly created elastomer is flexible and capable of self-healing when damaged. As a bonus, it also maintains consistent electrical conductivity when stretched.

The key to this material is the use of tiny metal droplets embedded inside a soft silicone-based elastomer. Those droplets, a gallium-indium (GA) alloy, rupture and flow out into the surrounding material when damaged. The droplets merge and form new electrical pathways that circumvent the damaged regions. The connection is robust enough to carry both power and data.

So, we’re not talking about the material’s structure healing, but rather its functionality. The real benefit here is no one needs to tell the material to heal itself. The entire process happens automatically when damage occurs. The GA droplets naturally merge and flow around damaged sections of silicone.

The team says this elastomer can recover from mechanical damage that would usually render a circuit non-functional. To prove the point, the researchers build several demonstration devices. There’s a digital clock that continues operating as more and more of the material is sliced off. More impressive is the soft robot that trundles along even after a cruel researcher uses a hole punch to damage the flexible circuit. From laboratory experiments, the team estimates that a circuit can still function even if 50 percent of it is damaged or destroyed.

This kind of self-healing circuit has numerous potential uses. The researchers point to wearable electronics has an ideal use case. You wouldn’t have to worry about wear and tear as much if the flexible electronic portions could heal. Likewise, robots that operate in remote areas could keep going after damage when no humans are around to repair them. Perhaps even rovers exploring other planets could benefit from flexible, self-healing materials. There usually isn’t anyone within a few million miles to fix them. Some applications may require modifications to droplet placement and size, though.

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