In the lab, Amsterdam physicists 3D-print unsupported ice structures

Inside a low-pressure chamber, an ice Christmas tree grows layer by layer in 26 min at 2 mbar. The University of Amsterdam physicists behind that demonstration—Menno Demmenie, Stefan Kooij and Daniel Bonn—have now shown that the same process can print small ice pillars at an angle, creating profiles that need no support from below.

The trick is evaporative cooling. In a vacuum chamber, water evaporates rapidly even at room temperature; each molecule that leaves carries away a small amount of heat, cooling the remaining liquid below zero degrees Celsius while it stays liquid. The ultrathin stream is 16 micrometers across, and it freezes instantly when it lands on an existing ice layer.

For the new result, printer speed is the control knob. Changing it lets the team print pillars at angles as small as 14 degrees to the surface, as well as profiles with almost any desired shape, including a human face. Unlike ordinary 3D printing, these angled forms do not need a structure beneath them for support.

The printed ice melts back into clean water when the vacuum pump is turned off. The paper points to possible uses in biology, where pure ice structures could act as tissue scaffolds, and in microfluidics, where melting the ice could leave intricate channels. Further ahead, the researchers say the same approach could be considered on Mars, whose cold conditions and thin atmosphere suit the process and where local water could provide the material.

So what, concretely? Biology and microfluidics researchers could use the method to shape pure ice into forms that are later removed by melting, while the Mars idea offers a possible route to building with local water. The reported work is still a laboratory demonstration: the paper shows printed ice structures and proposes these applications, rather than reporting a deployed scaffold, device or off-Earth construction project.