The smallest Eiffel Tower in the world is located in the province of Baden (Germany). In an inconspicuous plastic box, embedded in black foam, it looks like a beige colored crumb. Only a microscope can reveal how much detail the miniature model of the famous iron structure actually replicates. It is just 1 mm high. For Michael Thiel, its builder, that's already really big: "Often I cannot see what I have actually created here," the physicist explains. He printed the Eiffel Tower with a 3D printer developed by him and his team. "It is a hundred times more accurate than any other 3D printer," he says.
During his doctoral thesis at the Karlsruhe Institute of Technology (Germany), he investigated how lasers can be used to harden certain liquid plastics. "The accuracy depends on how sharply the laser is focused." The target material is only solidified in the spot where the laser strikes the liquid plastic. Thus, with special optics, extremely fine structures can be produced.
Nanoscribe GmbH was founded in 2007 in order to market this process. "Just half a year later we had sold the first printer," says Thiel. Currently, there are 100 of these printers in operation - at costs for each in the six-digit range.
Scientists at the Leibniz Institute for Solid State and Materials Research in Dresden (Germany) used this printer to produce a drive system for sperms. The helical drive from the 3-D printer can be magnetized, and with the help of rotating magnetic fields it can thus precisely deliver the sperm to the egg to fertilize it. The driving principle could make novel nanorobots possible.