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" On Tuesday, researchers at the Vienna University of Technology (TU Vienna) announced a new 3D printing technology capable of creating intricately detailed structures at the nanometer scale with unprecedented speed. The process, called two-photon lithography (TPL), works by tracing a finely focused laser beam through a pool of resin. As the beam&amp;#039;s focal point\u2014just two photons wide\u2014pulses into the liquid, the resin hardens on that point and leaves behind a solid structure. As a demonstration of the printer&amp;#039;s capabilities, researchers printed a 285-micrometer-long Indycar replica. It&amp;#039;s just larger than a few strands of hair.  Why a race car? Jan Torgersen, project assistant at TU Vienna&amp;#039;s Institute of Materials Science and Technology, says &amp;quot;It just fits high-speed printing.&amp;quot; Although high resolution has always been a major strength of TPL, as objects are printed nanometers at a time, speed has not. Previous technologies, such as the one German research institute Laser Zentrum Hannover developed, trudged along at a rate of millimeters per second. According to Torgersen, his team&amp;#039;s method can print at rates of meters per second, which amounts to a thousandfold increase.       This speed increase comes from the development of a specialized, fast-reacting resin, and a system of tuned mirrors that guide the laser pulses through the liquid. Previous TPL setups used a feedback system to control the mirrors that would check to make sure the resin had hardened and that the mirrors were properly aligned before shooting each pulse. Torgersen&amp;#039;s team instead used a preprogrammed set of delays, which kept the mirrors in constant motion, increasing the pulse speed and therefore the printing speed. It wasn&amp;#039;t easy: Without feedback control, researchers had to fine-tune the delays between the movements of the mirrors while ensuring that the laser pulses could keep up. &amp;quot;This synchronization of the switching of the laser and the movement of the mirrors was thus very tricky,&amp;quot; Torgersen says.  A nanoscopic Indycar is a nice demo, but Torgersen says the real applications of being able to quickly fabricate high-precision nanoscale objects lies in biomedical engineering\u2014for instance, creating scaffolds upon which to grow human tissue in the lab. &amp;quot;Depending on the geometry of the scaffold and the type of cell, custom biological tissue can be made,&amp;quot; he says.  A medical breakthrough like that is still a few years down the line, Torgersen says. TPL requires a femtosecond laser like those used in eye surgery, which typically costs in excess of $75,000. And commercially available resins can&amp;#039;t harden fast enough to keep up with the TU Vienna\u2013developed system. &amp;quot;I&amp;#039;m sure that the commercialization will come with the offer and demand of femtosecond lasers,&amp;quot; he says. For now, we&amp;#039;ll just have to admire race cars that are smaller than a common dust mite. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/technology/design/a7556/advanced-3d-printer-creates-nano-indycar-7358796/>