In production, 3D printing has become an increasingly important method. Up to now, a weak point of 3D printing has been the realization of metallic structures at the micrometer scale. Researchers at the Swiss Federal Institute of Technology in Zurich (ETH) have now developed a new 3D printing technique. According to a press release, this even allows two metals to be printed at the same time with a spatial resolution of 250 nanometers. The technique is also ten times faster than existing electrochemical printing methods.
Conventional methods for 3D-metal printing are ink based, which means that the desired metal is dissolved as nanoparticles in a suspension and delivered to a surface through a printing nozzle. An advantage of such inks is that they can be made with a variety of materials. However, they require a post-printing treatment that involves heating. This results in a shrinking and pronounced porosity of the material, explains ETH researcher Alain Reiser: “Typically, this means that the metallic structures are less conductive, mechanically unstable and, moreover, often contaminated with the organic compounds of the liquid solvent.”
Researcher at ETH have now come up with an alternative to this method: the metals is no longer deposited as a nanoparticle, but rather transported in the shape of electrically charged metal ions. Those ions are created by applying an electric voltage to a “sacrificial anode” consisting of the desired metal inside the printing nozzle. The ions are then sprayed by electric forces inside a solvent onto the printing surface, where they lose their electric charge and reassemble as a metal.
The researchers at ETH are currently collaborating with experts on printed electronic circuits in order to produce extremely thin connecting wires to organic semiconductors using their 3D printing method. They aim to extend the range of metals used in the future. In the long run, Alain Reiser believes the production of photosensors, printed integrated circuits and mechanical metamaterials should be possible with this technique.