This biohybrid micro swimmer is covered with magnetic material. Its swimming ability is largely unaffected by the coating.
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Flagella Movement and Swimming Speed of the Biohybrids
The robots’ flagella, which perform a breast-stroke movement, allowed the algae to catapult themselves forward like a speeding bullet.
They maintained their swimming speed after magnetization, demonstrating an average swimming speed of 115 micrometres per second (about 12 body lengths per second).
Magnetic Control and Steering of Microalgae Microrobots
Birgül Akolpoglu and Saadet Fatma Baltaci, who co-led the study, are scientists from the Physical Intelligence Department at MPI-IS.
A few years ago, they investigated how bacteria-based micro swimmers could be magnetically controlled in fluidic spaces for drug delivery applications. Now they have turned their attention to microalgae.
Their aim was to functionalise the surface of the unicellular organisms with a magnetic material so that they could be steered in any desired direction – turning the microalgae into a microrobot.
Microalgae Coating and Magnetic Navigation
Coating the cells took only a few minutes, with – in the end – nine out of ten algae successfully covered with the magnetic nanoparticles.
Using external magnetic fields, they were able to control the direction in which the microalgae swam. The researchers then steered their robot along miniature 3D-printed cylinders, creating a highly confined environment where the largest dimension was just three times the size of the tiny microalgae.
Steering Systems and Magnetic Guidance
The team set up two different systems to test the steering: one with magnetic coils and another with permanent magnets around their microscope.
They created a uniform magnetic field and repeatedly changed its direction. “We found that microalgal biohybrids navigate 3D-printed microchannels in three ways: backtracking, crossing, and magnetic crossing.
Without magnetic guidance, the algae often got stuck and backtracked to the start. But with magnetic control, they moved more smoothly, avoiding boundaries,” says the co-first author of the publication, Birgül Akolpoglu about their proof-of-concept study. “Magnetic guidance helped the biohybrids align with the direction of the field, showing real potential for navigating in confined spaces – kind of like giving them a tiny GPS!”
Future Applications in Biomedicine by the Max Planck Institute for Intelligent Systems
“Our vision is to use the microrobots in complex and small environments that are highly confined, such as those found in our tissues. Our findings open doors to applications such as targeted drug delivery, providing a biocompatible solution for medical treatments with exciting potential for future innovations in biomedicine and beyond,” the team concludes.
