Virginia Tech's breakthrough in flexible electronics tech

Virginia Polytechnic Institute and State University researchers presented their findings in the journal "Nature Electronics." They introduced an innovative approach to creating flexible printed circuit boards. Their method allows for efficient current flow between system layers without drilling holes, which is crucial for the miniaturization and flexibility of future electronics. Although commercial applications are still far off, this marks a new direction in developing flexible electronics.

The new technique relies on using liquid metal microparticles to create a stair-like structure. This architecture forms small, conductive connections both within and between circuit layers. The process involves the targeted placement of liquid metal droplets in a photosensitive resin, which is then illuminated with UV rays. This method remains versatile and can be adapted to various materials.

"This brings us closer to exciting possibilities like advanced soft robotics, wearable devices, and electronics that can stretch, bend, and twist while maintaining high functionality," says project leader Prof. Michael Bartlett.

The research team harnessed typically undesirable effects that appear when working with UV-cured materials, known as mask edge anomalies. They turned this problem into an advantage—the edges of UV-exposed areas cause the liquid metal droplets to settle and layer up in a stair-like pattern.

"By leveraging these otherwise unwanted edge effects, we can create soft, conductive vias that connect different circuit layers in a rapid and parallel fashion. We can do this all while maintaining flexibility and mechanical integrity of the soft device," explains the lead author of the publication, Dr. Dong Hae Ho.

Integrating connections both within and between layers enables the creation of soft, flexible circuits with a complex, multilayered architecture.

"This enables new forms of soft electronics, where multiple soft vias and interconnects are created in a parallel and spatially controlled manner. This is crucial for advancing the field," emphasizes Prof. Bartlett.

Flexible electronics may, for instance, offer a new approach to creating smartphones. Currently, manufacturers are focusing on foldable smartphones. In the future, they may consider using rollable screens. The first attempts have already been made with devices like the Motorola Rizr.