Researchers at Finland’s Aalto University have made a groundbreaking discovery in the field of microbiology and physics by utilizing magnets to align bacteria as they swim. This innovative approach not only offers a method to manipulate bacteria but also provides a valuable tool for various research areas, including complex materials, phase transitions, and condensed matter physics.
In the study led by assistant professor Jaakko Timonen, bacterial cells are mixed with millions of magnetic nanoparticles in a liquid solution. Although the bacteria themselves are not magnetic, the rod-shaped bacteria act as non-magnetic voids within the magnetic fluid. When a magnetic field is applied, the bacteria are coerced to align with the field due to the lower energy required for this configuration. This alignment is achieved by creating a torque on the bacteria’s bodies, pushing them to line up.
The strength of the magnetic field plays a crucial role in determining the alignment of the bacteria. With the magnets turned off, the bacteria move randomly. As the magnetic field intensity increases, the bacteria gradually align themselves into nearly perfect rows. The density of the bacteria population also impacts alignment, requiring a stronger magnetic field to overcome the turbulence-like effect caused by the swimming bacteria in dense suspensions.
The phenomenon of active turbulence, generated by the collective movements of individual units like swimming bacteria or other cells, is a key area of study in active matter physics. The dense bacterial suspensions used in the researchers’ system serve as a valuable tool for investigating active turbulence. This type of turbulence is distinct from traditional turbulence encountered in aviation, as it arises from the dynamic behavior of living organisms.
Beyond the novelty of controlling bacteria with magnets, this research has far-reaching implications. The ability to manipulate bacterial movement and turbulence is essential for understanding and manipulating active matter, where dynamic patterns emerge from individual parts’ actions. This knowledge can be applied to various fields, such as self-sustaining materials, microrobotics, and targeted drug delivery on a microscopic level.
The researchers are looking to expand their work by exploring the effects of dynamic magnetic fields, such as rotating magnetic fields. This continuous exploration and experimentation will further enhance the understanding of bacterial behavior and its applications in various scientific domains. The versatile nature of this method opens up possibilities for studying active matter in diverse systems beyond bacterial suspensions.
The use of magnets to control bacteria in research represents a significant advancement in scientific understanding and experimental capabilities. By harnessing the power of magnetic fields to manipulate bacterial behavior, researchers can delve deeper into the complexities of active matter and pave the way for innovative applications in the fields of physics, materials science, and biotechnology.