Self-Healing Circuits and the Quest for Indestructibility

Jonathan Strickland


Whether it's due to environmental changes, the effects of aging, a clumsy character played by Peter Sellers or a conspiratorial planned obsolescence, stuff eventually breaks. Most of the time, the only recourse we have is to call up someone to repair our stuff or go out and buy another . . . whatever it was that's busted.

But what if our stuff could fix itself? Self-repairing and self-healing materials could dramatically increase the longevity of everything from the roads we drive on to the electronics we carry around with us. In the case of circuits, the secret lies within some self-healing power amplifiers.

I read in Wired that a team at Caltech, aka the California Institute of Technology, has developed a type of amplifier for integrated circuits that can dynamically react to changing conditions so that it maintains its output as close to the ideal as possible. If a complementary metal-oxide-semiconductor (CMOS) chip experiences vast temperature changes or power surges, its performance can suffer. The same is true for aging - the chip degrades over time and doesn't perform up to the same standards as it did fresh out of the clean room.

The team developed an approach that allows the chip to monitor actual conditions and respond to them in real time. Sensors on the chip detect conditions that impact performance. A complex algorithm helps the chip to determine the right course of action to minimize performance impact. Even if part of the chip is destroyed -- something the team demonstrated by zapping parts of the chips they made with high-powered lasers -- the system as a whole can adjust and stay as close to optimal performance as it can.

In this context, self-healing doesn't mean the chip is physically repairing itself. There are no nanobots rushing to repair broken connections. Instead, the chip chooses the best state for damaged transistors so that the problems that would otherwise impact performance are managed as much as is possible. It's not a magic wand, but it does mean a chip can perform well even without the need for external maintenance.

This isn't a perfect analogy, but imagine you're driving through an unfamiliar town. Your navigation system is getting real-time updates on road conditions and traffic. As you make your way through your pre-planned route, the GPS gets an alert that one of the roads you are scheduled to drive down is currently closed. The system dynamically plans out a new route to get you around the closed road with a minimum impact to your driving time. That's similar to what the team at Caltech has done with their work in self-healing power amplifiers.

Ultimately, this technology will lead to electronics that are more robust. They'll be able to perform well in a wider variety of environmental conditions and stay viable longer than circuitry without the self-healing feature. Cutting down on the need for maintenance can also save time, energy and money. We aren't quite at the point where we can make a liquid terminator capable of repairing itself from near-total destruction, but it's a nice start.