Self-healing Electronics is Coming With Extended Life and for Reducing Waste

A total chip or even the entire device can collapse, if just one very small circuit within an integrated chip stops working or fails. Wouldn’t it be fantastic, if it could repair itself, and repair itself so quickly that the user never realized there was a fault?

A self-healing system has been developed by a team of engineers from University of Illinois. It is capable of reinstating electrical conductivity to a faulty circuit in less time than it takes to flicker. Aerospace engineering professor Scott White and materials science and engineering professor Nancy Sottos are the leaders of this team of researchers. They disclosed their results in the journal Advanced Materials.

"It simplifies the system," said chemistry professor Jeffrey Moore, a co-writer of the paper. "Rather than having to build in redundancies or to build in a sensory diagnostics system, this material is designed to take care of the problem itself."

Now-a-days manufacturers are putting as much density onto a chip as possible because electronic devices are evolving to execute more advanced tasks. Because of this kind of density, reliability is compromised. For example, failure stemming from unstable temperature cycles as the device operates or exhausts. The entire device can be shut down because of a failure at any point.

"In general there's not much avenue for manual repair," Sottos said. "Sometimes you just can't get to the inside. In a multilayer integrated circuit, there's no opening it up. Normally you just replace the whole chip. It's true for a battery too. You can't pull a battery apart and try to find the source of the failure."

Except some significant applications – like instruments or vehicles for space or military functions where electrical failures cannot be replaced or repaired, most other consumer devices are intended to be replaced with some frequency, adding to electronic waste issues.

In the past, a system for self-healing polymer materials was developed by the Illinois team and they opted to adapt their technique for conductive systems. They disseminated very small microcapsules which are tiny as 10 microns in diameter, on top of a gold line acting as a circuit. When a cleft inseminates, the microcapsules break open and release the liquid metal contained inside. To reinstate electrical flow, the liquid metal fills up the gap in the circuit.

"What's really cool about this paper is it's the first example of taking the microcapsule-based healing approach and applying it to a new function," White said. "Everything prior to this has been on structural repair. This is on conductivity restoration. It shows the concept translates to other things as well."

Because of the immediate filling of the crack by the liquid metal, the current flow is interrupted for mere microseconds by a failure. It is attested by the researchers that 90% of their samples healed to 99 percent of initial conductivity, even with a small amount of microcapsules.

Being localized and autonomous are the other advantages of the self-repairing system. Only those microcapsules are opened, which are intercepted by crack, so repair only takes place at the point of damage. In addition to that, no human interference or diagnostics is needed, which is a blessing for those applications where accessing a cleft for repair is not possible, such as a battery, or searching for the source of a failure is very difficult, such as an air- or spacecraft.