Researchers Print Stretchable Circuits That Heal Themselves

To demonstrate the technology, the researchers built a prototype touch sensor. Credit: Jingyan Dong, North Carolina State University

North Carolina State University researchers may have found a new way to print flexible (and stretchable) electronic circuits.

In a recent study, researchers Yiwei Han and Jingyan Dong used electrohydrodynamic (EHD) printing technology to create metallic conductors with sub 50 µm resolution that are not only electrically stable but also durable enough to stand up to hundreds of bending and stretching cycles.

The new fabrication method, published in the journal Advanced Materials Technologies, could be a window to next-generation electronics.

The researchers used EHD to print three different molten metal alloys onto glass, paper, as well as a pair of stretchable polymers. EHD is common in many manufacturing processes that typically use ink. This study was unique in that the researchers were direct printing metal alloys with melting points down to 60°C.

According to researcher Jingyan Dong, this method could reduce the cost of making high-resolution circuits, which could finally bring the price point low enough to employ the technology in commercial devices.

In tests, circuit conductivity survived 1,000 bend cycles and even remained viable after the conductors were stretched to 70% of tensile strain. When they did break, the conductors were easy to fix, because, given the low melting point, researchers could heat the area to ~70°C which enabled the metal to flow back together.

To demonstrate the technology, the researchers built a prototype touch sensor, but the team is now looking for partners to employ the method in electronic device markets, such as wearable sensors.

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