Virginia tech pioneers groundbreaking flexible electronics method

Virginia Polytechnic Institute and State University researchers presented a novel approach to creating flexible printed circuit boards in the journal "Nature Electronics". The developed method allows for efficient current flow between layers of the circuit without needing to drill holes, which is crucial for the miniaturisation and flexibility of future electronics. Although commercial applications are still far off, this signals a new direction in developing flexible electronics.

The new technique uses microdroplets of liquid metal to create a staircase-like structure. This architecture forms small, conductive connections within and between the circuit's layers. The process involves placing liquid metal droplets in photosensitive resin and then exposure to UV rays. The method remains versatile and can be applied with various materials.

Prof. Michael Bartlett, project leader, says this brings 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 utilised typically undesirable effects that occur when working with UV-cured materials. These imperfections are known as mask edge anomalies. The problem was turned into an advantage—the edges of areas exposed to ultraviolet light caused the liquid metal droplets to deposit and layer themselves into a pattern resembling 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 the publication's lead author, Dr. Dong Hae Ho.

Integration of connections within and between the layers allows for the creation of soft, flexible circuits with a complex, multi-layered 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 progress in this field," emphasises Prof. Bartlett.

Flexible electronics may result in 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—an example of such a device is the Motorola Razr.