Scientists have developed a new type of “electronic ink” that can be used to print electronic circuits that can switch between hard and soft states when heated.
This technology can pave the way for next-generation electronic devices that change shape or stiffness depending on how they are used and where they are used.
The ink is combined with gallium. Gallium is solid at room temperature but dissolves just below body temperature (98.6 degrees Fahrenheit (37 degrees Celsius)). The result is a stable, printable material that becomes electrically conductive after heating and can change its stiffness in response to temperature.
You might like it
The survey results were published in Science Advances on May 30th.
“This opens up new possibilities for future personal electronics, medical devices and robotics,” said Jae Woo Jung, co-author of electrical engineering at the Korea Institute of Advanced Science and Technology (KAIST) in a statement.
Related: Unique transistors can change the world of electronics with nanosecond scale switching speeds and wear rejection
Most electronic devices today fall into one of two camps. Strict devices such as smartphones and laptops offer performance and durability at the expense of flexibility. Or soft systems such as wearables can be more comfortable to wear, but can be difficult to manufacture accurately or integrate with more complex components.
From hardware to software
The so-called variable rigidity electronics aims to fill this gap, allowing devices to shift between hard and soft states as needed.
Gallium has long been attracting attention in the region because of its behavior in solid and liquid form. However, using it on printed electronics proves difficult due to its high surface tension and its tendency to oxidize upon exposure to air, forming a kind of crust that prevents it from bonding or properly diffusing.
To address this, researchers have developed a process in which microscopic gallium particles are dispersed on an essentially flexible ink-like base using a solvent called dimethyl sulfoxide (DMSO).
When the printed circuit is gently heated, the solvent decomposes, creating a slightly acidic environment. This removes the oxide layer from the gallium particles and allows it to melt and fuse to form conductive paths.
The resulting ink can be used to print small features as 50 micrometers (0.002 inches or 0.005 cm) – thinner than human hair – can be alternated with plastic-like hardness and rubbery softness if desired. Researchers said the ingredients became more than 1,400 times softer when warmed during testing.
The team built two working devices to demonstrate how Bendy technology was used. One is a wearable health device that behaves like a hard portable electronic at room temperature, softens and improves comfort when in contact with the skin. The other was a flexible brain implant that was inserted precisely as it remained rigid during the surgery, which helped to soften it once in the brain to reduce irritation and inflammation.
Inks can be used in common manufacturing techniques such as screen printing and dip coating. That means it could be used in large-scale or 3D printed electronic devices in the future, the researchers said.
“The central result of this research is to overcome the longstanding challenges of liquid metal printing through our innovative technology,” John said in a statement. “By controlling the acidity of the ink, printed gallium particles can be electrically and mechanically connected, providing room temperature manufacturing of high-resolution large area circuits with adjustable rigidity.”
Source link
