May 3, 2017

3D printing in micrometer format

					Micro 3D printing

Micro 3D printing is gaining ground. The number of providers in this new field of technology is growing. And with it the choice of additive manufacturing processes for microformat components.

This CMOS microchip could, in future, take the place of a number of cameras and sensors. Researchers at the University of Stuttgart have accommodated more than a dozen tiny lenses with different focal lengths on such a chip. These deliver images that the miniaturized imaging system then combines to produce high-resolution environmental data. Possible applications: vehicles, factories and medical applications.

These micro-objective lenses were manufactured using a 3D printer made by Nanoscribe. This spin-off from the Karlsruhe Institute of Technology specializes in micro-format and nano-format additive production. Laser pulses in the femtosecond range are used to shape photosensitive coatings. The strongly focused pulses harden only tiny areas of the coating, each of which absorbs two photons. Under this two-photon polymerization process the precision components gradually grow and take shape, pulse by pulse. The possible applications range from micro lenses, through tiny components for optics, medical technology, fluidics, electronics and mechanics, right up to cell frameworks made of biocompatible material or bionic micro-surfaces similar to sharkskin or lotus leaves.

Young companies driving technology forward

Nanoscribe, founded in 2008, has almost become an institution in the micro 3D printing market. New suppliers are constantly emerging and expanding the range of materials and applications available. These include the Chemnitz company 3D MicroPrint GmbH, which was founded in 2013 and manufactures laser sintering systems that print micro-metal components: tiny grippers, complex nozzles and miniaturized lightweight constructions. Varying the wall thickness, using internal lattices and cavities, and positioning ducts inside the components enable weight to be reduced by up to 60% compared to conventional production processes. To achieve this the focused laser constructs precision elements, with walls up to 30 μm thick, from individual layers of metal powder. Stainless steels, molybdenum and tungsten are available.

The Fraunhofer spin-off Multiphoton Optics, which was also founded in 2013, is working on printed solutions for three-dimensional photonic chips, laser diodes and fiber optic connections. Its founder, Dr. Ruth Houbertz, sees the manufacture of such 3D components as a “milestone in optical data transmission”. To achieve this goal, Multiphoton Optics has developed the high-precision 3D printing platform LithoProf3D and the associated software—and has recently entered into cooperation with the mechanical engineering company Heidelberger Druckmaschinen AG. Together, these unlikely partners want to bring the process to industrial maturity. In February, the team received the coveted Fraunhofer Founders’ Award. The jury’s reasoning: “Multiphoton Optics fills the gap between electronics and photonics and opens up new possibilities for the future of data transmission.”

Lab-on-chip, microlenses and optical sensors from the printer

Two more of today’s young micro 3D printing companies are the Swiss company Femtoprint SA and LightFab from Aachen. Both specialize in precision components made of glass and other transparent materials. These components, which can be given any desired form and may contain embedded conduits, are used by laboratories and medical technology manufacturers as lab-on-chips or miniature reactors. Photonics manufacturers use them to produce sensors and actuators, lenses and polarization converters. And the watch industry also relies on the printed precision offered by the founder teams.

Both teams work with femtosecond lasers in the near-infrared range. They use resolutions in the sub-micrometer range to laser 3D structures made of quartz and borosilicate glass, sapphire or transparent plastics. The next step of this subtractive 3D process uses chemicals to dissolve the structures modified by the focused laser. LightFab advertises that its 3D printer can also control other laser processing methods—precise removal of hard and brittle material, writing 3D waveguides in glass, or additive micro 3D printing using two-photon polymerization. The founder teams will be reporting in more detail in Munich, from June 26–29, 2017—as exhibitors at the LASER World of PHOTONICS.