Scientists 3D Print a Cell-Sized Boat, the World’s Smallest

Finally, we have a boat that could sail down a human hair.

Physicists at Leiden University have 3D printed the world’s smallest boat: a 30-micrometer copy of Benchy the tug boat, a well-known 3D printer test object. The boat is so tiny, it could float down the interior of a human hair.

To be precise, it’s a third smaller than the thickness of a human hair and about six times larger than a bacteria cell. It’s also surprisingly detailed, with an open cockpit featuring some tricky geometry that made the process more difficult. The goal of the experiment was to understand how “microswimmers” like bacteria and sperm move through liquids.

The image was made using an electron microscope and was published in an article by the authors about 3D printing synthetic microswimmers in the scientific journal Soft Matter. Image credit: University of Leiden

To 3D print such a miniscule object, the team used a commercial Nanoscribe 3D microprinter applying a process called 2PP (two-photon polymerization). The 3D prints are created inside droplets using material that hardens at the focal point of extremely accurate lasers.

To see the process live, check out the microscale 3D printing of a spaceship:

The most interesting part of the experiment is how they were able to print the little boat’s cockpit, an open space that requires lots of geometric trickery to build.

“A laser is focused inside a droplet that locally hardens in the focal spot of the laser,” said researcher Daniela Kraft. “By moving the laser through the droplet in a controlled way, we can write the swimmer shape that we want.”

A bigger version of Benchy. Image credit: 3D Benchy

“Because the print is taking place inside the droplet, and we are printing layer by layer, we can maintain the open space [inside the tugboat cockpit],” she said.

OK, but why exactly did the researchers print a little swimming boat? Because it was fun!

“3D Benchy is a structure that has been designed to test macroscopic 3D printers because it has several challenging features, and it was natural to also try it at the micrometer scale,” said Kraft. “In addition, making a swimming micrometer-sized boat is fun.”

Sources: 1, 2, 3


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