Vienna's St. Stephen's Cathedral; All images: Vienna University of Technology
Researchers at the Vienna University of Technology (TU Vienna) have created the first complex works of nanoarchitecture. Using their own custom made high-precision 3-D printer, the team recreated models of Vienna's St. Stephen's Cathedral and London's Tower Bridge at the scale of a dust mite. The feat was made possible through two-photon lithography, whereby a laser is guided by a chain of controllable mirrors through a liquid resin to form a solid polymer line only several hundred nanometers wide. The resin solidifies only when the initiator molecules within in have absorbed two photons of the spent laser beam at once, or when the polymer molecules fall directly under the laser's central focal point.
The experiment's achievement, however, lay in the rapid rate at which the printer laid down material lines. Whereas "the printing speed [of similar printers] used to be measured in millimeters per second," says Professor Jürgen Stampfl of TU Vienna, "our device can do five meters in one second." The machine can produce 100 layers, each comprised of 200 lines, in only four minutes (see video below)--a high wire act of incredible precision involving the perfect synchronization of the constantly moving mirrors. University scientists hope to develop and introduce bio-compatible resins into the process for medical applications, wherein infinitesimal infrastructures could be printed to buttress cells leading to the creation of biological tissues.
London's Tower Bridge