The aim was to see how microorganisms like sperm or bacteria swim.
Physicists at Leiden University in the Netherlands have 3D printed what could be the world’s smallest boat, a test object known as Benchy (via Gizmodo). At 30 microns long, it’s a third smaller than the thickness of a human hair and about six times larger than a bacteria cell. It’s not only small but surprisingly detailed, with an open cockpit that features some tricky geometry. The goal is to understand how “microswimmers” like bacteria and sperm move through liquids.
To 3D print an object that small, the team used a commercial Nanoscribe 3D microprinter using a process known as 2PP (two-photon polymerization), as shown in the manufacturer’s video below. The 3D prints are created inside droplets with material that hardens at the focal point of extremely accurate lasers.
“By moving the laser through the droplet in a controlled way, we can write the swimmer shape that we want,” said researcher Daniela Kraft. “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].”
The team created the boat because it was “fun,” but also developed more research-specific shapes, including a spiral less than 5 microns in diameter. By tracking the motion, they were able to measure the speed and path of different types of particles.
The 3D printing technique opens the door to the creation of very specific shapes in order to emulate biological microswimmers or optimize their motion through fluids. “Ultimately, it will allow a greater control and design of the behavior of synthetic microswimmers, useful for applications in therapeutic diagnostics and drug delivery,” according to the research paper.