Are 3D printers not amazing enough already? Apparently some scientists at the Vienna University of Technology (TU Vienna) didn't think so, as they have now built one that can create intricate objects as small as a grain of sand. While the ability to 3D-print such tiny items is actually not unique to the TU Vienna device, the speed at which it can do so is. According to the researchers, this makes the commercial production of things such as medical implants much more viable.
The printer uses an existing process called "two-photon lithography," and utilizes a special type of liquid resin. That resin contains molecules which cause the liquid around them to harden into a polymer, once they're exposed to laser light. In order to be activated, however, they must absorb two photons of that light at once. The only place where the beam is intense enough for that to happen is right at its center. This allows for great precision in the printing process, as only the very middle of the beam is the "active" part.
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Additionally, unlike traditional 3D printing, two-photon lithography allows for solid material to be created anywhere within the depth of the liquid resin - it isn't limited to simply adding to a surface layer of hardened material.
Along with the resin, another one of the keys to the Vienna printer's peppy performance is a high-speed motorized mirror system, that directs the beam of the laser within that resin. Because the mirrors are constantly in motion throughout the printing process, their acceleration and deceleration times have been minimized as much as possible, in order that more of their time can be spent on the actual creation of the object.
"The printing speed [of two-photon lithography] used to be measured in millimeters per second," said Prof. Jürgen Stampfl. "Our device can do five meters in one second."
As can be seen in the video below, the printer is currently pretty darn good at building things such as tiny race car models - it can make one that's a mere 285 micrometers long in just four minutes. A bio-compatible resin is currently in the works, however, which could hopefully be used to build micro-scaffolding for a patient's living cells to grow into, in the creation of biological tissues.
Source: TU Vienna