Flexible electronics technology offers groundbreaking solutions across aerospace, human-machine interaction, biomedical, and clean energy sectors. This is achieved through the utilization of bendable and stretchable electronic materials, along with innovative structural designs. At its core, this technology harnesses advancements in materials science, electronic engineering, and nanotechnology to ensure stable performance even in extreme environments. Metallic thin films, serving as crucial conductive materials in flexible electronics, play a pivotal role in electrical connections and signal transmission. However, they have long been plagued by fatigue issues stemming from cyclic deformation.

Traditional nanocrystalline metallic thin films are susceptible to premature fatigue crack initiation and rapid crack propagation. This is attributed to abnormal grain growth and strain localization, ultimately leading to a sharp rise in resistance and even circuit failure. While alloying and multilayering techniques can enhance high-cycle fatigue resistance, they often come at the cost of electrical ductility and reduced low-cycle fatigue life. This trade-off makes it challenging to achieve synergistic optimization, posing a significant hurdle to the widespread engineering applications of flexible electronics.

To address this challenge, the research team led by Academician Jun Sun at the National Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, has proposed a groundbreaking "coherent gradient nano-layered structure" design strategy. By constructing metallic multilayer films with both atomic-level coherent interfaces and layer-by-layer gradient transitions, this design effectively suppresses fatigue crack initiation and propagation. This provides a novel and robust solution for ensuring the long-term service reliability of flexible conductors.

The beauty of this design lies in its universality, as it can be readily extended to various metallic systems, including gold, copper, and aluminum. Moreover, it is highly compatible with existing microfabrication technologies, showcasing strong potential for industrialization and large-scale production.

To validate the practicality of their design, the team successfully fabricated three types of prototype devices: implantable bioelectrodes, flexible light-emitting displays, and flexible interconnect circuits. These prototypes have demonstrated their feasibility for applications in healthcare, human-machine interaction, and intelligent sensing, respectively. This achievement paves a practical pathway for overcoming the long-standing reliability bottlenecks in flexible electronics, opening up new avenues for their widespread adoption and integration into various industries.