A recent study in the International Journal of Extreme Manufacturing showcases the swift advancements in transforming metallic materials into flexible electrodes (FEs) and, ultimately, soft epidermal electrodes (SEEs).
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Metals have been highly valued for their exceptional electrical conductivity for a considerable time. However, their inflexibility has traditionally excluded them from the competition to create flexible, skin-like electronics. A surge of research is now changing this perspective, turning metals into stretchable, breathable, and even self-healing components for the next generation of wearable technology.
In contrast to the conventional rigid metal pads utilized in medical monitoring, SEEs are designed to replicate the softness and elasticity of human skin. They fit seamlessly like an additional layer of tissue, ensuring comfort even during prolonged use while providing consistent, high-quality signals.
The transition from rigid metal to flexible electrode has evolved in three significant ways. Some scientists design ultrathin metallic films into complex meshes, resulting in lightweight structures that maintain conductivity while enhancing flexibility and transparency.
Another approach focuses on metal nanowires, particularly silver, whose nanoscale size enables the creation of highly conductive yet stretchable networks that can absorb strain.
A third avenue is propelled by liquid metals, which merge fluidity with excellent conductivity and possess the capability to self-repair when injured.
Collectively, these methods are transforming metals' capabilities, resulting in electrodes that are transparent, stretchable, and sufficiently durable for everyday use on the body.
One particularly thrilling area of exploration is the creation of ultrathin SEEs, or U-SEEs, which can be applied to the skin similarly to a temporary tattoo. These devices are produced using both in situ and transfer-based techniques, enabling them to establish close, conformal contact that facilitates the sensing of bioelectric signals, stimulation of nerves or muscles, and even energy harvesting—all while being nearly undetectable to the user. Their potential applications range from personalized healthcare to sophisticated rehabilitation and the integration of human and machine.
However, the way ahead is fraught with challenges. Metal meshes have the potential to disperse light and may weaken when subjected to tension. Although nanowires are highly effective, they are susceptible to corrosion and thermal damage.
Metal meshes can experience optical haze and have restricted durability when under stress; nanowires face risks of corrosion and instability; and liquid metals introduce complications in processing and safety. Equally important, the integration of these flexible elements with rigid chips and power supplies continues to be a significant obstacle.
The researchers are also addressing practical challenges such as ensuring breathability, skin-safe adhesion, and long-term reliability—all of which are crucial for daily use.
The advancements are quite encouraging. The researchers are currently investigating composite designs that merge the optimal characteristics of various metallic systems to achieve a balance of flexibility, conductivity, and transparency. Concurrently, scalable manufacturing techniques such as 3D printing, aerosol jet printing, and roll-to-roll processing are being enhanced to bring these technologies nearer to mass production.
Building on this groundwork, artificial intelligence and multimodal sensing are anticipated to transform these epidermal systems into intelligent platforms capable of predictive healthcare and next-generation human–machine interaction.
We hope these advances will allow epidermal electronics to integrate effortlessly into daily life, supporting personalized healthcare, rehabilitation, and beyond.
Jeong Ho Cho, Corresponding Author and Professor, Yonsei University
The previously inflexible world of metals is now adapting to human requirements, transforming into warm, skin-like companions that could soon be as commonplace to wear as garments—heralding a future in which electronics are not merely worn, but integrated into daily life.
Journal Reference
Zhu, H., et al. (2025) Nano/micro-engineered metallic flexible electrodes: advancing the era of epidermal electronics. International Journal of Extreme Manufacturing. doi.org/10.1088/2631-7990/ae02ca