Liquid metals: A solid foundation for flexible electronics

Flexible electronics is an incredibly popular, interdisciplinary field with an ever-expanding frontier. Among the most cutting-edge technologies is the implementation of liquid metals (LMs).

Chen et al. systematically reviewed LM’s applications in flexible electronics to understand their origin and future development.

If a metal is liquid at room temperature, it is an LM. Many metals fit this classification, but only a few are practical. Mercury is a commonly known LM, but its toxicity disqualifies it from many applications. Other metals may be rare or radioactive. To avoid these challenges, the team focused primarily on gallium-based LMs.

LMs may be used on their own, or, more favorably, as part of a metal or polymer composite.

“When different metal particles are doped in LMs, they produce alloys with new characteristics,” said author Sen Chen. “Composites not only inherit the merits of LMs and metal particles but also incubate some unknown, new characteristics, which is a situation where one plus one is greater than two.

“In the case of LM polymer composites, not only do the numerous types of polymers impart different properties to the liquid metal, but the polymers can encapsulate the LM. The resulting composites have mechanical properties (such as stretchability) that LMs do not have while avoiding problems such as corrosion of the contact interface by the LM.”

There are many different approaches to applying LMs, from LM printed electronics, LM flexible electronics with channels, and LM/polymer flexible electronics. Each application requires different fabrication methods.

Though these fields have promising innovations, manufacturing technology and precision control of LM properties, like surface tension and liquidity, remain significant challenges.

Source: “Liquid metal flexible electronics: Past, present, and future,” by Sen Chen, Ziliang Cui, Hongzhang Wang, Xuelin Wang, and Jing Liu, Applied Physics Reviews (2023). The article can be accessed at https://doi.org/10.1063/5.0140629 .

This paper is part of the Flexible and Smart Electronics Collection, learn more here .