Scientists have developed a new type of “electronic ink” which can be used to print electronic circuits capable of switching between rigid and soft states when heated.
Technology could open the way for new generation electronic devices that change shape or rigidity depending on how and how they are used, medical implants that soften the body with flexible robotics.
The ink combines gallium, a solid metal at room temperature but melts just below the body temperature – 98.6 degrees fahrenheit (37 degrees Celsius) – with a polymer-The solvent based on it when it is gently heated. The result is a stable and printable substance which becomes conductive after heating and can change its rigidity in response to temperature.
The results were published on May 30 in the journal Scientific advances.
“This opens up new possibilities for future personal electronic devices, medical devices and robotics”, co-author of the study Jae-Woong JeongElectric engineering professor at Korea Advanced Institute of Science and Technology (KAIST), said in a statement.
Most electronic devices fall today in one of the two camps: rigid devices such as smartphones and laptopswhich offer performance and sustainability at the price of flexibility; Or soft systems like portable devices, which are more comfortable to wear but can be more difficult to make with precision or integrate with more complex components.
Material to softness
The so-called variable-stiffneté electronics aims to fill this gap, allowing devices to move between hard and soft states if necessary.
Gallium has long attracted interest in this area because of the way it behaves differently in solid and liquid forms. But using it for printed electronics has proven to be difficult because of its high surface tension and its tendency to oxidize when it is exposed to air, forming a sort of crust which prevents it from binding or propagating properly.
To remedy this, researchers have developed a process of dispersion of microscopic gallium particles in a polymer matrix – essentially a flexible base in Ink type – using a solvent called dimethyl sulfoxide (DMSO).
When the printed circuit is heated gently, the solvent breaks down and creates a slightly acidic environment. This eliminates the oxide layer from Gallium particles, allowing them to melt and merge to form conductive pathways.
The resulting ink can be used to print features as small as 50 micrometers (0.002 inch or 0.005 centimeters) – Damiered than human hair – and can alternate between plastic hardness and rubber softness if necessary. The researchers said that the material has become more than 1,400 times softer when heated during tests.
The team has built two work devices to demonstrate how Bendy technology could be used. One was a portable health device that behaves like a rigid portable electronics at room temperature, then softens contact with the skin to improve comfort. The other was a flexible brain implant that remained rigid during surgery so that it could be inserted with precision, then softened once inside the brain to help reduce irritation and inflammation.
Ink can be used with common manufacturing techniques such as screen printing and dip covering, which means that it could be used on a larger scale or 3D print Electronic in the future, the researchers said.
“The fundamental realization of this research is to overcome the long -standing challenges of the printing of liquid metals thanks to our innovative technology,” said Jeong in the press release. “By controlling the acidity of the ink, we were able to electrically and mechanically connect the printed gallium particles, allowing the manufacturing at room temperature of large resolution circuits with large region with tinnable rigidity.”