Paper is a product that we can use for many purposes, such as writing, printing, packaging and crafting. What if paper could do more than hold ink or fold into shape? What if paper could transform itself into smart objects that could sense, act and communicate? This may sound like science fiction, but a group of researchers from China recently published the paper. by coating with liquid metal He developed a new method that gave him unprecedented possibilities.

Liquid metal, a type of metal that remains liquid at or slightly above room temperature; It has many characteristics such as high conductivity, low fluidity and self-healing. liquid metal; such as circuits, sensors and actuators creating flexible and stretchable electronics can be used for.

However, applying liquid metal to paper or other substrates is a bit tricky because liquid metal tends to form droplets and doesn’t adhere well without glue, so scientists have found a way around this.

Researchers led by Bo Yuan of Tsinghua University, of bismuth, indium and tin oxide They found a solution to this problem by using a special alloy consisting of (BiInSn). This alloy gallium or eutectic gallium-indium (EGaIn) has a higher melting point than other liquid metals, meaning it can be solidified and stamped onto paper without dripping or spreading. The alloy too does not oxidize when exposed to airmaking it more stable and stickier.

To coat the paper with BiInSn, the researchers first melted the alloy in a crucible and then poured it into a silicone mold. They then pressed the mold onto a piece of paper with moderate pressure and speed. The result is on the paper surface. a thin and even layer of liquid metal it happened. The researchers repeated this process on both sides of the paper to create a double-sided coating.

The coated paper showed remarkable properties. Can conduct electricity and heat, making it light up the LEDs and resistors. It can also sense changes in touch, pressure and temperature. In addition, it could fold itself into different shapes by applying an external magnetic field. The researchers demonstrated this by making an origami cube from coated paper. If they open the cube and place it next to a magnet, The paper folds itself back into its original shape.

Are smart papers entering our lives?

The researchers think their method could open up new possibilities for creating smart paper devices that can perform various functions. For example, they can move and interact with their environment. paper based robotsThey envision paper-based displays that can change colors and patterns, and paper-based sensors that can monitor health and environmental conditions.

The method is also simple and scalable, which means it can be applied to large-scale production of smart paper products. Regardless of the thickness, texture or color of their method, the researchers claims to be able to coat any type of paper with liquid metal. They also suggest that materials other than paper could be coated with liquid metal using the same technique.

(You can find the research published in Cell Reports Physical Science on June 22, 2023 here.)