Liquid Metal Drops Make Silicone 40x More Thermally Conductive

A Virginia Tech graduate student mixed eutectic gallium-indium into uncured PDMS silicone, creating a composite that can guide heat and autonomously heal electrical circuits. The work comes from the Soft Materials and Structures Lab, and tomshardware.com reported on the findings.

The metal is roughly three parts gallium and one part indium and remains liquid at room temperature. When mixed into the silicone, it forms droplets on the order of 10 to 100 microns in diameter. About an hour in an oven turns the silicone from a gel into a solid while the droplets stay liquid.

A 2025 paper in Advanced Functional Materials reported the printed composite's thermal conductivity along the droplets' direction at 9.9 W/mK, about 40 times that of unfilled silicone. A 2024 paper in Additive Manufacturing noted that the oxide skin plays a critical role in reconfiguring and retaining droplet shape. A setting that controls the ratio of extrusion speed to print bed speed determines droplet shape.

The lab's website says the droplets give the composite soft elasticity, extreme toughness, and autonomously self-healing electrical circuits. In a demonstration, pressing a line into a cast slab merged droplets into a conductive track that lit a small LED. Cutting the track with a razor blade and pressing near the cut restored faint LED illumination.

Hugh Grennan said cutting or puncturing reforms pathways and the liquid metal flows through them. The video was filmed at VT MADE, the university's New Center for Advanced Manufacturing.

Separately, Nvidia's GeForce RTX 5090 Founders Edition uses a gallium alloy in place of thermal paste. IDC puts worldwide wearables shipments in the first quarter of 2026 at 145.7 million units, up 4.3% year over year.