Speaker
Description
There is a growing tendency to confine motile microorganisms, such as bacteria, within narrow channels for the purpose of studying their chemotaxis, signaling, and interactions, or to model their motility in porous media. When the width of the channels is comparable to the size of the microorganisms, the free trajectories of two microswimmers can be significantly disrupted when they meet. A retardation occurs and clusters may form, which could limit the use and applicability of microfluidic devices. In this study, we present an expression for the maximum swimmer density that can be accommodated within a microchannel to avoid clustering. This expression depends on simple kinematic properties of single microswimmers and pairs of microswimmers at collisions that can be readily measured. The proposed methodology for measuring the required parameters is applied to the case of bacteria Bradyrhizobium diazoefficiens moving in long microchannels of cross section 1.8 μm × 1.8 μm. The advantage of this approach is that it does not necessitate the determination of an effective density-dependent speed, which is a requisite of the standard motility induced phase separation theory.
