First of its kind gel repairs circuits.

A team of engineers at the Cockrell School of Engineering at The University of Texas at Austin have developed a novel self-healing gel that, they say, can repair and connect electronic circuits, which could lead to advancements in the development of flexible electronics, biosensors, and batteries. They say that although commercial technology is moving toward lighter, flexible, foldable, and rollable electronics, currently available circuits to power them are not built to flex freely and repeatedly self-repair cracks or breaks that can happen from normal wear and tear.

Fig. 1 – Self-repaired supergel supports its own weight after being sliced in half.
While some self-healing materials are available, they have relied on application of external stimuli such as light or heat to activate repair. The university’s “supergel” material has high conductivity as well as strong mechanical and electrical self-healing properties.

“In the last decade, the self-healing concept has been popularized by people working on different applications, but this is the first time it has been done without external stimuli,” said Mechanical Engineering Assistant Professor Guihua Yu, who developed the gel.

Yu and his team combined two gels—a self-assembling metal-ligand gel that provides self-healing properties and a polymer hydrogel that is a conductor to create the self-healing gel. (See Figure 1)

The researchers used a disc-shaped liquid crystal molecule to enhance the conductivity, biocompatibility, and permeability of their polymer hydrogel. They say that they were able to achieve about 10 times the conductivity of other polymer hydrogels used in bioelectronics and conventional rechargeable batteries. The nanostructures that make up the gel are the smallest structures capable of providing efficient charge and energy transport.

The second ingredient of the self-healing hybrid gel is a metal-ligand supramolecular gel. Using terpyridine molecules to create the framework and zinc atoms as a structural glue, the molecules form structures that are able to self-assemble, giving it the ability to automatically heal after a break.

When the supramolecular gel is introduced into the polymer hydrogel, forming the hybrid gel, its mechanical strength and elasticity are enhanced.

To construct the self-healing electronic circuit, Yu believes the self-healing gel would not replace the typical metal conductors that transport electricity, but it could be used as a soft joint, joining other parts of the circuit. The team is also looking into other applications, including medical applications and energy storage, where it holds tremendous potential to be used within batteries to better store electrical charge.

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