Magnetized Algae Microswimmers Navigate Confined Spaces with High Precision

Researchers at the Max Planck Institute for Intelligent Systems (MPI-IS) have engineered magnetized algae microswimmers capable of navigating tight spaces with impressive speed and control. Published in Matter on March 17, 2025, this work explores how functionalized microalgae perform in confined and viscous environments—advancing applications in drug delivery and microscale material handling.

Magnetized algae microswimmers are single-cell algae coated with magnetic nanoparticles. The coating allows scientists to steer them using external magnetic fields. The team used Chlamydomonas reinhardtii, a well-known motile green alga, as the base organism. Each cell measures around 10 micrometers and swims using two flagella in a breaststroke-like motion.

The researchers coated the algae with a natural polymer, chitosan, mixed with magnetic nanoparticles. The chitosan promotes adhesion, while the nanoparticles enable magnetic control.

The study revealed that the algae maintained high-speed swimming after magnetization. The coated microswimmers reached average speeds of 115 micrometers per second, or 12 body lengths per second. For comparison, Olympic swimmer Michael Phelps swims at around 1.4 body lengths per second.

Despite the added magnetic load, the microswimmers retained their speed and mobility. This makes them ideal candidates for navigating complex biological or engineered environments.

The team tested the biohybrids in 3D-printed microchannels with dimensions only three times the size of the algae. Without magnetic guidance, the microswimmers often got stuck or backtracked. But when controlled by a magnetic field, they moved efficiently through the channels.

They displayed three modes of movement:

• Backtracking
• Crossing
• Magnetic crossing

Using permanent magnets or magnetic coils, researchers could shift the field direction in real-time, guiding the algae like microscopic robots.

To simulate environments like mucus, the researchers increased the fluid’s viscosity. As expected, the microswimmers slowed down in thicker fluids. However, when magnetic fields were applied, the algae adapted by moving in zigzag patterns. This confirmed their potential to operate in realistic biological environments, where fluids often vary in density and composition.

While the study’s main focus lies in biomedicine and microrobotics, the findings hold relevance for powder technology as well. Here’s how:

The use of magnetic nanoparticles parallels particle coating techniques in powder engineering. Surface functionalization improves dispersion, flowability, and targeted behavior—core topics in powder processing.

Whether it’s powder injection molding, tablet filling, or microfluidic dosing, controlling how particles move through small spaces is vital. In this context, the study provides valuable insights into the real-time steering of functionalized particles within viscous and confined systems, offering guidance for designing more precise and adaptive processes.

Controlled delivery systems in pharmaceuticals often rely on powdered drug formulations. Therefore, understanding micro-scale navigation plays a key role in designing smarter inhalable powders, targeted granules, or encapsulated agents that respond effectively within the body.

If your team focuses on smart coatings, magnetic guidance, or flow optimization, this research offers a compelling example of how biological inspiration can inform powder system design—bridging disciplines to create more responsive, efficient delivery platforms.

“Our vision is to use the microrobots in complex and small environments that are highly confined, such as those found in our tissues,” said co-author Saadet Fatma Baltaci.

With this goal in mind, the study sets the stage for biocompatible drug delivery systems capable of reaching previously inaccessible areas. Ultimately, this advancement could enhance both precision medicine and targeted material transport in the field of biomedical engineering.

Magnetized algae microswimmers are more than a novel concept. In fact, they represent a fusion of biology, nanomaterials, and control systems—together, these elements are pushing the boundaries of what’s possible in both microscale robotics and applied material science.

Meanwhile, as powder technology evolves toward smarter, more responsive systems, research like this offers valuable insights that could inspire new approaches across multiple disciplines.

• Akolpoglu, M. B., Baltaci, S. F., Bozuyuk, U., Karaz, S., & Sitti, M. (2025). Navigating microalgal biohybrids through confinements with magnetic guidance. Matter, 8(3). DOI 10.1016j.matt.2025.102052
• Max Planck Institute for Intelligent Systems. (2025, March 19). Scientists Create Microscopic Algae Robots With Incredible Swimming Abilities. Retrieved from https://www.is.mpg.de