3D printing, also known as additive manufacturing, has played an extensive role in the production of large, complex components recently. Earlier this year, we covered how 3D printing was being used to build the world's largest printed neighborhood, consisting of 100 3D-printed homes, and how the technique was used to print a school in Africa in just 18 hours.
Now, a group of scientists has set a new benchmark in 3D printing.
In a paper published in the scientific journal Nano Letters, Dr. Dmitry Momotenko, a chemist at the University of Oldenburg, along with a team of researchers from ETH Zurich, Switzerland, and Nanyang Technological University, succeeded in fabricating ultrasmall metal objects using the new technique.
According to the team, their modus operandi can be used to make objects out of copper just 25 billionths of a meter in diameter (equivalent to 25 nanometres).
Their electrochemical 3D printing technique fabricates complex conductive structures with nanometer resolution, and it could have potential applications in battery technology, microelectronics, sensor technology.
Go small or go home
The latest 3D printing technique revolves around the familiar process of electroplating. Momotenko's nanoprinting method requires a solution of positively-charged copper ions in a tiny pipette. The liquid emerges from the tip of the pipette through a print nozzle. In the experiments conducted, the nozzle opening had a diameter of between 253 and 1.6 nanometers. Only two copper ions can pass through such a tiny opening simultaneously.
The team then developed a technique to monitor the printing process. They recorded the electrical current between the negatively charged substrate electrode and a positive electrode inside the pipette. In an automated process, the nozzle approached the negative electrode for a very short time and then retracted as soon as the metal layer had exceeded a certain thickness.
Employing this technique, the researchers gradually applied consecutive copper layers to the electrode's surface. The precise positioning of the nozzle lets them print vertical columns and spiral nanostructures. They could also produce horizontal structures by changing the printing direction.
According to the team, the smallest objects that can be printed by this method have a diameter of about 25 nanometres, which is equivalent to 195 copper atoms in a row.
The new electrochemical technique could be used to print far smaller metal objects that have never been printed before. The smallest objects that can be produced using this method are 4,000 times larger than those in the current study.
"The technology we are working on combines both worlds — metal printing and nanoscale precision," Momotenko told Phys.org. "3D-printed catalysts with high surface area and special geometry to allow particular reactivity could be prepared for the production of complex chemicals," he said.
Momotenko and his team are currently working towards improving the efficiency of electrical energy storage through three-dimensional electrodes. To speed up the charging process, their NANO-3D-LION project focuses on notably increasing the surface area of electrodes and reducing distances between the cathode and the anode in lithium-ion batteries through 3D printing.