Microscopic vehicles propelled by swimming green algae could assist biological and environmental research

Researchers have created tiny, vehiclelike structures that can be maneuvered by microscopic algae. The algae are caught in baskets attached to the micromachines, which have been carefully designed to allow them enough room to continue swimming.

Two types of vehicles were created: the "rotator," which spins like a wheel, and the "scooter," which was intended to move in a forward direction but in tests moved more surprisingly. The team is planning to try different and more complex designs for their next vehicles. In the future, these mini algae teams could be applied to assist with micro-level environmental engineering and research.

"We were inspired to try and harness Chlamydomonas reinhardtii, a very common algae found all over the world, after being impressed by its swift and unrestricted swimming capabilities," said Naoto Shimizu, a student from the Graduate School of Information Science and Technology at the University of Tokyo (at the time of the study), who initiated the project.

The micromachines were created using a 3D printing technology called two-photon stereolithography. This printer uses light to create microstructures from plastic. The team worked at a scale of 1 micrometer, equal to 0.001 millimeter. According to the researchers, the most challenging part was optimizing the design of the basket-shaped trap, so that it could effectively capture and hold the algae when they swam into it.

Image source: Oda et al. (2024), Small.