In the first three years of the Millennium Nucleus (2017-2020), the objective of this line of investigation was to develop the experimental capacity to confine and study the dynamics of bacterial suspensions in microfluidic devices.

To accomplish this, we used Escherichia coli (E.coli) as the first experimental and theoretical model. The reasons were: it is a very well-studied bacteria, its dense hives show collective motion, and the fact that being able to confine and manipulate it is relevant to create links with the biotechnology industry and open new lines of investigation applied to lab-on-a-chip technologies. In this new stage of the Millennial Nucleus (2021-2023), we plan to extend this study to other bacteria used in agriculture and mining applications, mainly soil and magnetotactic bacteria.

By confining bacteria in microdroplets, we were able to build motors of motors thanks to the coherent motion of bacteria. Nevertheless, these states are highly fluctuant, and we will perform experiments to characterize these fluctuations. Besides, with the application of magnetic fields, we seek to control these motors.

Using microfluidic devices that simulate the porosity of the soils, we seek to characterize and optimize the swimming motion of certain bacteria used as biofertilizers. Finally, our theoretical work showed different phases of accumulation of bacteria swimming near a wall. We will continue this work with walls of different geometries, and we will build microchannels with controlled roughness walls to study the accumulation of bacteria near the walls.