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Virginia Tech Lab 3D Prints Liquid Metal Composite for Enhanced Thermal Conductivity
Key points
- Eutectic gallium-indium (EGaIn) mixed into PDMS silicone.
- 3D printed composite shows 40x higher thermal conductivity.
- Droplets stretch into long, thin shapes for heat transfer.
- Potential uses include custom heat sinks and wearables.
New 3D Printing Method for Liquid Metal Composites
Virginia Tech graduate student Hugh Grennan demonstrated a new 3D printing technique involving a composite material made from eutectic gallium-indium (EGaIn) and polydimethylsiloxane (PDMS) silicone. The EGaIn, a liquid metal at room temperature, is mixed into uncured PDMS, forming droplets within the silicone.
Material Composition and Properties
The EGaIn consists of approximately three parts gallium to one part indium. When mixed with PDMS, the metal breaks into droplets, each encased in a thin gallium oxide skin. After curing the silicone, these droplets, ranging from 10 to 100 microns in diameter, remain liquid, contributing to the composite's soft elasticity, toughness, and self-healing electrical properties.
Enhanced Thermal Conductivity
The composite is printed using a syringe-fed machine. By controlling the ratio of nozzle extrusion speed to print bed movement, the spherical liquid metal droplets can be stretched into long, thin shapes. This configuration allows heat to travel efficiently along the elongated axis of the droplets, away from a heat source and towards a heat sink. Research published in Advanced Functional Materials (2025) indicates that the printed composite achieves a thermal conductivity of 9.9 W/mK along the droplet direction, which is about 40 times greater than that of the unfilled silicone.
Applications and Future Potential
The ability to precisely control the shape and arrangement of the liquid metal droplets within the silicone opens up new possibilities for thermal management. Potential applications for this 3D-printed material include the development of custom heat sinks and stretchable wearable devices that require efficient heat dissipation. The unique role of the oxide skin in maintaining droplet shape during reconfiguration was also highlighted in a 2024 paper in Additive Manufacturing.
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Reporting from
Researchers at Virginia Tech have developed a method to 3D print a liquid metal composite using eutectic gallium-indium mixed into silicone, achieving a 40x increase in thermal conductivity compared to unfilled silicone. This innovation allows for the creation of custom heat sinks and stretchable wearable devices that can efficiently guide heat.