Different views of the 3D-printed miniature David (1mm high) made of pure copper.
Photo: Giorgio Ercolano, Exaddon

A pure copper replica of Michelangelo’s David stands just 1mm tall including its pedestal. Giorgio Ercolano from Exaddon, an offshoot of ETH spin-off Cytosurge, created the micro-statue with the team led by ETH Prof. Tomaso Zambelli from the Laboratory of Biosensors and Bioelectronics. Zambelli’s research developed 3D-printing techniques a few years ago to print metal structures at the nanometer and micrometer scale, enabling the mini-David.

The process’ core component is a micropipette coupled to a cantilever, making it possible to monitor the force with which the point of the pipette touches the substrate. With this assembly, researchers can electrochemically deposit dissolved metals onto an electrically conductive substrate with high degree of precision. Optical force measurement automates the process for building minuscule metal structures layer-by-layer. Exaddon adopted this micrometal printing method and improved its speed, and other characteristics.

Printing complicated geometries

Ercolano printed micro-David to highlight the technology’s ability to print structures or geometries of all complexity levels. Printed in one step, without supports or templates, the sculpture didn’t require firing or tempering.

Data for the David sculpture is freely available on the Internet, Ercolano notes, adding that he “could even have printed the room that the statue is standing in – the data includes that as well.”

Size set by resolution

Ercolano 1.0mm David is actually a giant. He printed that one first and followed it with a 0.1mm David. With structures that small, achieving the required resolution becomes problematic. Printed metallic micro-objects typically starts at 1µm, and for more complex and detailed objects, sizes range from 100µm to 1mm. In terms of time, the 1mm model is a world away from the smaller one; the device needed 30 hours to create the big (1.0mm) David but just 20 minutes for the smaller version (0.1mm).

Theoretically, the system can print objects up to 5mm, but the printer cartridge contains only a microliter of ink – about enough to produce the larger David. However, it’s enough ink to print hundreds or even thousands of tiny objects, which represents the strength of the process.

“We’re thrilled that a technology from our research lab has made its way into practical application,” Zambelli says. “An independent group was able to adopt our 3D printing technology and even improve upon it, which shows that it really works.”

Ercolano and his colleagues published their results in the journal Micromachines.

ETH Zurich
https://ethz.ch

Exaddon AG
https://www.exaddon.com