Characterizing microbial motility - techniques and challenges

Motility is a defining characteristic of many organisms. It enables organisms to acquire nutrients, evade predators and explore their environment. However, studying the mechanics of motility becomes rapidly complex. From the biological side there are many factors to consider such as organism size and composition, energy availability and needs, the influence of their environment and the impact of long evolutionary time scales. From the physics side there are the challenges of bringing together theory and experiment: developing realistic models and simulations at different time/length scales and designing equipment/experiments to test them. After introducing these topics in a broader context, we will shift to techniques for studying bacterial motility. Although bacteria are single-celled organisms, there are different cell morphologies and a variety of motility phenotypes. We will focus especially on digital holographic microscopy and a discussion of 3D tracking challenges and techniques. The talk will conclude with a short introduction to current work on low-cost experimental methods for characterizing small robot motility in fluid environments at different Reynolds numbers. Future directions include bridging this work with its biological counterparts.