Virginia Tech Researchers Build Soft, Stretchable, Self-Healing, Recyclable Electronic Circuits

A team of researchers from Virginia Tech claim to have developed a new form of soft electronics that can stretch, survive "numerous damage events," and heal themselves automatically — and are even recyclable at the end of their lives.

Described in the paper covering the team's research as a "self-healing liquid metal composite," the new material aims to improve a number of aspects of current soft electronics — including their ability to operate while damaged and how recyclable they are once the device for which they are built is no longer needed.

"These skin-like electronics stretch to 1,200 percent strain with minimal change in electrical resistance, sustain numerous damage events under load without losing electrical conductivity, and are recycled to generate new devices at the end of life," the team summarizes of its work. "These soft composites with adaptive liquid metal microstructures can find broad use for soft electronics and robotics with improved lifetime and recyclability."

The secret: Tiny, conductive liquid metal droplets that are spread over a rubbery polymer as discrete, disconnected parts — but which can be selectively connected to build a circuit.

"To make circuits, we introduced a scalable approach through embossing, which allows us to rapidly create tunable circuits by selectively connecting droplets," first author Ravi Tutika, PhD, explains. "We can then locally break the droplets apart to remake circuits and can even completely dissolve the circuits to break all the connections to recycle the materials, and then start back at the beginning."

The resulting circuits are soft, flexible, and can working even if you punch a hole straight through them — routing around the damage by making new connections between droplets. When finished, both the elastomer and the metal droplets can be returned to a liquid solution and used to produce new electronics — "an approach," Virginia Tech claims, "that offers a pathway to sustainable electronics."

"We’re excited about our progress and envision these materials as key components for emerging soft technologies," says Michael Bartlett, PhD. "This work gets closer to creating soft circuitry that could survive in a variety of real-world applications."

The team's work has been published under open-access terms in the journal Communications Materials.