Researchers in Portugal are pioneering the use of gallium–carbon composites for 3D printing sensor-heater-battery systems in wearable electronics. These applications demand flexible, durable materials that maintain their functionality under strain. Gallium-based liquid metals (LMs) are ideal due to their high conductivity and fluidic deformability, but their low viscosity and high surface tension present significant printing challenges.

To address these issues, the team developed a gallium-carbon black-styrene isoprene block copolymer (Ga–CB–SIS) composite. This cost-effective and sustainable material substitutes traditional metals like silver with carbon. The Ga–CB–SIS composite is digitally printable and sinter-free, which eliminates the need for thermal sintering and enables multilayer 3D printing. It also exhibits excellent adhesion to various substrates, including heat-sensitive materials.

The Ga–CB–SIS composite can serve multiple functions, acting as interconnects, sensors, heaters, and electrodes for energy storage. One of its standout features is its self-healing property upon exposure to solvent vapor, which facilitates effective circuit repair. Additionally, the composite is recyclable, with gallium recovery demonstrated using a deep eutectic solvent (DES).

The researchers optimized the CB/Ga ratio to balance conductivity and mechanical integrity, finding that a CB/Ga ratio of 0.043 achieved low resistance and stable behavior under strain. This optimal ratio also ensured printability and stretchability, making the composite suitable for various applications, including low-resistance heaters, batteries, and electrical interconnects.

Overall, the Ga–CB–SIS composite represents a sustainable solution for 3D printing in wearable and recyclable electronics. It integrates sensor, battery, and heating functionalities into a single device, and its properties and printability pave the way for innovative applications in flexible and stretchable electronics. This advancement marks a significant step forward in the development of multifunctional, eco-friendly materials for next-generation wearable technology.

By Impact Lab