DYNA JOURNAL ENGINEERING

Physicists from the Institute of Physics at the University of Amsterdam have developed a 3D-printing technique that creates complex ice structures using nothing more than a thin jet of water inside a low-pressure chamber. Their most eye-catching result is a small, finely detailed Christmas tree, with clearly defined branches and ornaments, produced in just 26 minutes inside a transparent acrylic vacuum chamber.

The method relies on evaporative cooling, the same principle mammals use to regulate their body temperature through sweating. When the pressure in the chamber is reduced to just a few millibars, water evaporates extremely quickly at room temperature, taking heat away and cooling the remaining liquid below 0 degrees Celsius while it stays in a supercooled state. As soon as an ultra-thin water jet, only about 16 micrometers thick, hits the ice structure that is already formed, it freezes almost instantly, allowing the object to grow layer by layer.

The researchers have also shown that the same approach can be used to print cones, vertical pillars and even leaning, free-standing structures, all without support materials or waste. Beyond festive ornaments, they highlight potential uses in microfluidics and bioengineering, where pure ice templates could act as temporary molds or scaffolds that disappear cleanly when the ice is melted.

An important advantage of the technique is that it does not require expensive cryogenic infrastructure such as liquid nitrogen cooling or refrigerated chambers. Instead, it is based on relatively accessible components: a modified commercial 3D printer, a vacuum pump and an acrylic chamber. According to the team, this combination of simplicity, low cost and high visual impact could open the door to new scientific applications and make it a powerful teaching tool for demonstrating thermodynamics and phase transitions in real time.