Motion and transport in microorganisms / Bio- & geo-inspired novel mechanics
Motion and transport in live bacterial systems
Bacteria often live in a complex fluid environment while they are often exellent runners that can move up to 50 body-length in a second. This is like driving at 200 MPH in Yosemite (with very rough roads). It is crucial to know how these microorganisms overcome or make use of the complex environment in many biological processes, especially because it directly concerns human health. This study can be facilitated by our newly developed 3D tracking microscope, which follows each of these fast swimmers in 3D. We can now correlate the complicated motion of every individual to its unique structure and its encountered environments. We aim to be able to control the behaviors of microorganisms by alternating their structure or adjusting the mechanical properties of their living environments.
Rescaled table-top models of biological locomotion While a direct study of the live biological systems often appears appealing, we also design experiments of artificial table-top models that scale up or scale down the actual system to overcome the challeges due to biological complexities. By keeping the essence while removing the complex details from the live biological systems, we study the principles that govern the complex interplays between motion and mechanics in nature, from bacterial swimming (Top) to insect hovering (Bottom).
Novel mechanical materials
Origami structures have been recognized not only as aesthetic creations but also as a flatform of creating metamaterials with mechanical properties taylored by those innumerable folding patterns. By fabricating these elegant structures while performing mechanical characterization and mathematical modeling, we explore and invent novel mechanics that not necessarily exist in Nature.
Fluid-structure interaction in non-Newtonian flows Fluid-structure interactions in Non-Newtonian fluids (for instance, many polymer- or granular- suspensions) often lead to surprising dynamics and thus many potential applications. (Left.) A fluid "chisel" can be build up in front of a sphere moving through a layer of granular suspension (here, cornstarch-water mixture), which disappears gradually upon cease of motion. (Right.) An array of steadily rotating disks underneath a layer of polymeric solution results in asymmetric flow patterns, which also evolves over time.