Guiding microbes along their path

The curvature determines the flux

Surprisingly, the microbe was found not to move randomly though the open space. Instead, the average movement pattern was both highly organized and symmetrical: the map of movement patterns showed a defined distribution of probability fluxes. “In particular, the strength of the flux was found to depend on the curvature of the adjacent solid interface: a higher degree of curvature resulted in a stronger flux” explain Jan Cammann and Fabian Schwarzendahl, the lead authors of the study. For practical reasons, all measurements were done in a quasi 2-dimensional environment, meaning that the microbe was confined from the top and bottom to better monitor its movement and avoid defocusing. Observing its movement pattern, the group of Marco Mazza (University of Loughborough and MPIDS) created a model to predicts the probabilities to flow in a certain direction. This model was then applied to compartments with more complex interface curvatures and experimentally verified by the lab of Oliver Bäumchen (MPIDS and University of Bayreuth). “It turns out that the curvature of the interface is the dominating factor which directly determines the flux of the self-propelling microbe.,” Bäumchen summarizes.

A technological implication for the future

As this discovery constitutes a fundamental observation, the model might as well be applied to other areas of active matter physics. “With our model, we can basically statistically predict where the object of interest will be in the next moment,” Mazza reports. “This could not only significantly improve our understanding of the organization of life, but also help to engineer technical devices.”

Understanding the principles behind the organization of active matter therefore can have direct implications on our future technologies. Potential applications of the model could be directing the movement of photosynthetic microorganisms in such a way so their flux can propel a generator, which would be a direct way to convert sunlight into mechanical energy. But also, in the pharmaceutical and healthcare sector, the findings of the scientists might be applied: “A potential application in the medical sector is the development of micro-robots delivering drugs to their specific destination in an efficient manner,” Bäumchen concludes.

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Materials provided by Max Planck Institute for Dynamics and Self-Organization. Note: Content may be edited for style and length.