Virginia tech pioneers breakthrough in flexible electronics

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

The new technique uses liquid metal microparticles to create a structure resembling stairs. This architecture facilitates small, conductive connections both within and between circuit layers. The process involves the targeted placement of liquid metal droplets in a photosensitive resin, then illuminating the entire structure with UV rays. This method remains versatile and can be used with various materials.

Project leader Prof. Michael Bartlett says it will bring us closer to exciting technologies such as advanced soft robotics, wearable devices, and electronics that can stretch, bend, and twist while maintaining high functionality.

The research team capitalized on typically undesirable effects that appear when working with UV-cured materials, specifically imperfections known as mask edge anomalies. They turned these challenges into an advantage—by allowing the edges of the UV-exposed areas to cause liquid metal droplets to settle and layer up in a pattern reminiscent of stairs.

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

Integrating connections 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. Prof. Bartlett emphasizes that this is crucial for advancing the field.

Flexible electronics may lead to new approaches in smartphone design. Currently, manufacturers are focusing on foldable smartphones. In the future, they may consider using rollable screens. Initial attempts have already been made, such as the Motorola Razr.