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When liquid metal is released into water, its high surface tension makes it form droplets -- rather than streams. But when a low voltage is applied, the surface tension drops, allowing the liquid metal to stream out as hairlike filaments. Credit: Minyung Song, NC State University

Researchers from North Carolina State University have demonstrated a technique that allows them to produce streams of liquid metal at room temperature. By applying a low voltage to the liquid metal, the researchers were able to tune its surface tension across at least three orders of magnitude.

"Liquids want to form droplets, because that lowers their surface energy," says Michael Dickey, a professor of chemical and biomolecular engineering at NC State and co-corresponding author of the study. "And that's especially true for liquid metals, because they have much higher surface tension than other liquids."

Surface tension is measured in units of millinewtons per meter. Most liquids, such as gasoline or water, have surface tension values between 20 and 72 millinewtons per meter. Gallium alloys, which were used in the NC State study, have a surface tension of at least 500 millinewtons per meter.