Collective behaviors of self-propelling particles (SPP) are ubiquitous in nature. Fish schools, bird flocks, bacteria swarms, and traffic jam are a few good examples. The complex competition of local interactions and long range coupling between each SPP leads to collective dynamics. In particular, hydrodynamic interaction in fluidic environment can lead to hydrodynamic synchronization in microbiological system. On the other hand, the introduction of SPP such as bacteria into micro-fluidics devices has been considered in recent years. Employing the flagella rotational motions, issues that are related to the low Reynolds number characteristics in micro-fluidics devices may be overcome and improved. Previous studies show promising potentials for the application of SPP microfluidics system in microstructure manipulations, power generation, and fluid mixing enhancer. Our interests on this issue are on the physics of collective dynamics involved under low Reynolds number condition.

We have constructed a bio-microfluidic system for studying the above issues. We have found collective sub-diffusive dynamics in a bacterial carpet microfluidic channel and continue to explore the physics behind it. By employing different mutant strains of bacteria to create different force pattern in microfluidic channel, we are able to examine the hydrodynamic coupling near surface. An optical tweezers based force measurement system has been built up to measure the temporal and spatial distribution of force generated by the bacterial carpet. Furthermore, we work with our collaborator to efficiently produce high throughput microfluidic devices to enable our studies.

Involved lab members: