Scientists have finally discovered the strange mechanics allowing isolated drops of liquid metal to form an electrical network in soft materials.
In a recent paper published in Matter, Virginia Tech researcher Michael Bartlett, along with two Ph.D. candidates, Wuzhou Zu and Hugh P. Grennan explored the liquid metal mystery to finally discover an answer: tiny cracks.
Despite continuing advances in the soft electronics field, researchers have long struggled to understand precisely how electricity flows through these materials. Confusingly, droplets of liquid metal in the materials form networks, yet they remain separated by insulators.
Liquid Metal Mystery
“Our group and other researchers around the world have been using mechanical pressure to turn liquid metal composites into conductors for years, but we did not really understand what was happening inside the material,” said lead author Professor Michael Bartlett. “We wanted to uncover the physical mechanism that allows isolated liquid metal droplets to suddenly become an electrical network.”
Modern technology puts sensors and computers into almost every aspect of life. Putting these devices in certain areas requires wearables or other soft, bendable electronics. Liquid metal offers an important solution to this issue by adding pliability to metal’s conductivity, required to power these devices and move information.
The team’s research focused on eutectic gallium, a room-temperature liquid metal alloy. Putting the substance under a microscope reveals dynamic processes facilitating its conductivity. It forms into microscopic spherical droplets that come into contact with one another, producing new pathways for electrical current to pass between them as they merge.
These liquid metals require soft containers, usually composed of polymers or rubber, to hold them together. What confuses scientists is that these insulators will occupy spaces between the metal droplets. Therefore, those insulating materials should also block an electrical current from passing between the droplets, yet somehow, they still manage to maintain conductivity.
Analyzing Liquid Metal
Using 3D X-ray imaging and microscopes, the Virginia Tech team analyzed the eutectic gallium under various conditions, including inside compressed soft electronics. They discovered something interesting about that compression, which finally explained the mysterious conductivity: tiny cracks.
It turned out that when the material was under pressure, small cracks would appear in the insulator between the droplets, which the liquid metal would then start to fill in. Even when the pressure ceased, the metal would remain inside these cracks, allowing the electricity to bypass the insulator.
“We were able to watch the process happen in two dimensions and then reconstruct the pathways in three dimensions,” Zu said. “That gave us a much clearer picture of how local cracks and liquid transport build into a larger conductive network.”
Modeling Strange Conductivity
After their analysis, the team went a step further by developing a mathematical model to determine the force needed to induce conductivity in soft materials. This is a crucial breakthrough for engineers designing soft electrical devices, allowing better control over conductivity formation. Applications include stretchable sensors, wearable electronics, and soft robots, all growing categories as computers and online connectivity enter more aspects of our lives.
“Knowing what governs how conductive networks form, we can use that knowledge to guide materials design and manufacturing,” Bartlett concluded. “That opens the door to manufacturing soft electronic systems where conductivity is programmed in through the material architecture and the way the device is processed.”
The paper, “Fracture-Mediated Percolation Governs Electrical Activation in Liquid Metal Composite Conductors,” appeared in Matter on October 29, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.