Alex Parrish, Virginia Tech
Current passes through a self-healing circuit

Soft, Flexible Circuitry Maintains Power

June 28, 2021
Researchers have engineered a new self-healing, flexible circuit for use in electronic devices.

A team of researchers have created a new type of soft circuit electronics that can be used in cell phones and laptops.

The soft circuitry is intended to replace inflexible, rigid materials that use soldered wires throughout electronic devices, noted the Virginia Tech researchers from the Department of Mechanical Engineering and the Macromolecules Innovation Institute.

Led by assistant professor Michael Bartlett, the research team described the characteristics of skin-like circuits as soft and stretchy, with an ability to sustain damage events under load without losing electrical conductivity. In addition, the soft circuit can be recycled to generate new circuits at the end of a product’s life.

These new electronic composites and tiny, electricity-conducting liquid metal droplets are part of a rapidly emerging field of technology that gives gadgets a level of durability that would have been impossible just a few years ago, noted the researchers.

How it Works

The researchers explained that liquid metal droplets are dispersed in an elastomer, a type of rubbery polymer, as electrically insulated, discrete drops. The reconfigurable droplets and reprocessable polymer matrix enable robust, electrical circuitry is self-healing and reconfigurable.

“To make circuits, we introduced a scalable approach through embossing, which allows us to rapidly create tunable circuits by selectively connecting droplets,” postdoctoral researcher and first author Ravi Tutika said. “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.”

Due to the circuits’ flexibility, it continues to work even under extreme stress or damage. For instance, if the circuit is punctured, the droplets make new connections around the hole to complete the circuit and pass electricity. Compare this property to using traditional wire, where an interrupted connection means cutting power. 

Another property of the stretchy material is that the circuit will stretch to more than 10 times its originally length without losing electrical connection or failure. 

Once the material reaches its end of life, the metal droplets and the rubbery materials can be reprocessed and returned to a liquid solution. From that point, noted the researchers, they can be “remade to start a new life.” This recyclable characteristic offers a pathway and to sustainable electronics, but also holds promise for wearable electronics and soft robotics.

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

Findings of the research were published in Communications Materials, an open access journal from Nature Research.

About the Author

Rehana Begg | Editor-in-Chief, Machine Design

As Machine Design’s content lead, Rehana Begg is tasked with elevating the voice of the design and multi-disciplinary engineer in the face of digital transformation and engineering innovation. Begg has more than 24 years of editorial experience and has spent the past decade in the trenches of industrial manufacturing, focusing on new technologies, manufacturing innovation and business. Her B2B career has taken her from corporate boardrooms to plant floors and underground mining stopes, covering everything from automation & IIoT, robotics, mechanical design and additive manufacturing to plant operations, maintenance, reliability and continuous improvement. Begg holds an MBA, a Master of Journalism degree, and a BA (Hons.) in Political Science. She is committed to lifelong learning and feeds her passion for innovation in publishing, transparent science and clear communication by attending relevant conferences and seminars/workshops. 

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