Flexible electronics have long been a goal of scientists and engineers, as they have the potential to revolutionize wearable technology, medical devices, soft robots, and other systems. To achieve this, researchers have been seeking out materials that can be used to create electronics of varying shapes and sizes.
Among the most promising materials are liquid metals made from gallium alloys. These alloys have fluid properties that make them highly conductive, making them ideal for the creation of soft and flexible electronics.
However, building three-dimensional (3D) circuits using any liquid metals has proven to be a challenge, limiting the possible structures that can be created. But now, researchers at the Harbin Institute of Technology and the Chinese Academy of Sciences have found a solution. They have successfully created flexible electronics with 3D circuits using a liquid gallium-indium alloy.
Their paper, published in Nature Electronics, describes how the gallium alloy they used possesses the necessary properties for developing flexible electronics, including a solid-liquid phase transition, mechanical strength, and good plasticity in its solid state.
To fabricate the flexible electronics, the researchers cooled a bulk sample of the alloy to low temperatures and then shaped it into solid metallic wires and sheets. These were then formed into circuits at low temperatures (below 15 degrees Celsius) and encapsulated in an elastomer before being heated above their melting temperature.
By encapsulating the liquid metal structures and heating them to above 22.7 degrees Celsius, the team ensured that the structures regained their fluidity, resulting in a stretchable liquid metal that can conduct electricity and be used to create flexible electronic components.
The researchers used this technique to create high-sensitivity strain sensors, 3D interconnect arches for integrating arrays of light-emitting diodes (LEDs), and a 3D wearable sensor and multilayer flexible circuit board for monitoring finger motion.
These alloy structures have the potential to revolutionize the field of flexible electronics, as they can be used to fabricate stretchable electronics for wearable devices and soft robotic systems. Additionally, this technique could be used to create liquid metal structures based on other alloys and materials. The possibilities are endless, and the future of flexible electronics looks bright.