While printed electronics conjure up notions of being able to manufacture electronic devices far more simply and cheaply than traditional electronics, the reality is that the resulting devices are so delicate that they are prone to an early demise that all but snuffs out any savings that might have been gained.
Now, researchers at the University of California San Diego (UCSD) have developed a new type of magnetic ink that produces electronic devices with self-healing capabilities. The UCSD researchers believe that this self-healing quality will make printed electronics far more robust, and therefore more viable for a number of new applications.
"Our work holds considerable promise for widespread practical applications for long-lasting printed electronic devices," said Joseph Wang, director of the Center for Wearable Sensors and chair of the nanoengineering department at UC San Diego, in a press release.
In research described in the journal Science Advances, the researcher created microparticles that orient themselves in a particular way when in the presence of a magnetic field. Unlike other self-healing materials, this one does not require an external force to trigger the self-healing process.
The material is capable of repairing tears as wide as three millimeters, which is a record in the annals of self-healing materials.
And it patches itself up rather quickly. The self-healing material can fix tears in 50 milliseconds; other self-healing materials can take minutes (and sometimes days) to repair themselves.
To test out its healing properties, the researchers used the ink to fabricate printed batteries. (You can download a video demonstrating the battery here.)
They cut the material or tore it apart; it never lost its ability to heal itself, nor did it losing more than a tiny bit of its conductivity.
To make the ink able to pull itself together, the researchers loaded it with a magnetic material called neodymium. The magnetic field of these particles is bigger than their actual size, and so when the material is torn, the particles just pull it all back together.
The obstacle that the researchers had to overcome was the magnetic field of the particles canceling each other out. The trick was another magnetic field. When the ink was printed in the form of a circuit, it was done in the presence of another magnetic field, which made the particles orient themselves as a permanent magnet at the two polar ends of the printed device. With one end positive and the other negative, the two magnets attract each other when divided into two parts.
This looks like it could be a boon for wearable electronics and perhaps a host of other applications in which printed electronics has appeared promising but hasn’t really been able to break through. Among these other uses are batteries and sensors.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.