Virginia Tech lab 3D prints a liquid metal composite to guide heat, boost thermal conductivity 40x

Virginia Tech graduate student Hugh Grennan mixed eutectic gallium-indium (EGaIn) into uncured polydimethylsiloxane (PDMS) silicone in a “3D Printing LIQUID METAL!” video on the 3D Printing Nerd YouTube channel hosted by Joel Telling. He cast a slab of the mixture, pressed a line into it to light an LED, sliced that line with a razor blade to show it still conducted, and then printed the same material on a syringe-fed printer to guide heat rather than electricity.

The metal is eutectic gallium-indium, which Grennan described as “about three parts gallium, one part indium” that, once mixed, is “liquid at room temperature.” The lab’s website says the droplets give the composite “soft elasticity” and “extreme toughness,” along with “autonomously self-healing electrical circuits.”

The metal is mixed into the uncured PDMS, which breaks it into separate droplets, each wrapped in a thin gallium oxide skin. …