Researchers at the University of Oldenburg used a process similar to electroplating to print 3D structures in the range of 25 nm. Of course, human hair is thousands of times thicker than it. The working medium is copper salt and a very small nozzle. How small is it? As small as 1.6 nm. This is sufficient to accommodate two copper ions at the same time.
Tiny nozzles can easily become the bane of every 3D printer: clogged nozzles. In order to alleviate this situation, the research team established a closed-loop control device to measure the current in the working area and inside the nozzle. You can read the full text online.
The size of the object depends on the nozzle size and other electrochemical parameters. At 25 nm, there are less than 200 copper atoms. For example, when printed with powder, the bottom is about 100 microns. It’s really small. You must wonder whether we will see the printing of small integrated circuits in the next few decades. We’re not sure what else you can do with such a small structure.
If you don’t mind making things bigger, you can set up your own metal plating printer. But be careful: they are very slow. Actually, it’s different, but just as you can have a 3D printing pen, you can also make an electroplating pen.