Chinese scientists have unveiled a groundbreaking method that could revolutionise the world of electronics. Everyday materials such as paper and plastic can now be transformed into electronic "smart devices" through the application of liquid metal, according to a study published in the prestigious journal Cell Reports Physical Science.
The research team, led by Bo Yuan from Tsinghua University, has devised a simple yet innovative technique to apply liquid metal coatings to surfaces that typically resist bonding with this remarkable material. The study showcases the potential for this approach to be implemented on a large scale, opening doors to wearable testing platforms, flexible devices, and even soft robotics.
Yuan explained the significance of their discovery, stating, "Before, we thought that it was impossible for liquid metal to adhere to non-wetting surfaces so easily, but here it can adhere to various surfaces only by adjusting the pressure, which is very interesting."
Previously, the scientific community faced challenges in combining liquid metal with conventional materials due to its high surface tension, preventing effective binding with most substances, including paper. Previous attempts relied on the "transfer printing" technique, which employed a third material to facilitate adhesion. However, this method introduced complexities and potentially compromised the electrical, thermal, or mechanical performance of the final product.
To address these limitations, Yuan and the team pursued an alternative m, allowing direct printing of liquid metal onto substrates while preserving its properties. They applied two different types of liquid metal, eGaln and BilnSn, onto various silicone and silicone polymer stamps, exerting varying forces as they rubbed the stamps onto paper surfaces.
The researchers made significant strides in achieving stable adhesion of the liquid metal coating to the substrate after extensive experimentation. They discovered that applying a small amount of force while rubbing the liquid metal-covered stamp onto the paper facilitated effective binding, while excessive force disrupted the droplets' stability.
Furthermore, the team demonstrated the versatility of the technique by folding the metal-coated paper into a paper crane, highlighting that the surface remained foldable and retained its original properties even after the process.
Despite these remarkable advancements, Yuan acknowledged that ensuring the durability of the liquid metal coating after application remains a challenge. Currently, the solution involves adding a packaging material to the paper's surface, but the team is determined to find an alternative that eliminates this requirement.
Yuan remarked, "Just like wet ink on paper can be wiped off by hand, the liquid metal coating without packaging here also can be wiped off by the object it touches as it is applied. The properties of the coating itself will not be greatly affected, but objects in contact may be soiled."
Looking ahead, the researchers plan to expand the method's applicability to a wider range of surfaces, including metal and ceramic. Additionally, they aim to leverage this breakthrough to construct innovative smart devices using materials treated with this novel approach.
As the future of technology gravitates towards flexible and curved alternatives, this liquid metal breakthrough promises to reshape the landscape of electronics, offering limitless possibilities for next-generation devices that seamlessly integrate with our everyday lives.
