Active colloidal fluids: a new paradigm in self-assembly

ChE Seminar Series Presents:

Petia M. Vlahovska, PhD
Professor of Engineering Sciences and Applied Mathematics (by courtesy)
Mechanical Engineering, Northwestern University

Title: Active colloidal fluids: a new paradigm in self-assembly

Abstract:

Flocks of birds and schools of fish are familiar examples of emergent collective behavior, where interactions between self-propelled (active) individuals lead to coherent motion on a scale much larger than the isolated unit. Similar phenomena have been observed with active micro-particles such as bacteria and motile colloids.  Recently, the Quincke instability (spontaneous spinning of a dielectric particle in an applied uniform DC field) has attracted great interest as a means of propelling colloids, by simply letting the particles roll on a surface.   In this talk, I will present our experiments showing how Quincke rollers, previously studied mainly as active Brownian particles, can be designed to perform Run-and-Tumble-like locomotion mimicking bacteria such as E. coli. Populations of the Quincke random walkers self-organize and exhibit behaviors reminiscent of bacterial suspensions such as dynamic clusters and mesoscale turbulent-like flows. When enclosed in a drop, the Quincke rollers drive strong shape fluctuations and drop motility resembling amoeba crawling. I will also discuss some novel collective dynamics of Quincke rotors levitating in a bulk fluid: unlike the rollers, the “hovers” form crystals, chains and other dynamical assemblies.

Bio:

Petia M. Vlahovska received a PhD in chemical engineering from Yale (2003) and MS in chemistry from Sofia University, Bulgaria (1994). She was a postdoctoral fellow in the Membrane Biophysics Lab at the Max Planck Institute of Colloids and Interfaces and spent ten years on the faculty at Dartmouth College and Brown University, before joining the faculty at Northwestern University in 2017. Her research is in fluid dynamics, membrane biophysics, and soft matter. Dr. Vlahovska is the recipient of David Crighton Fellowship (2005), NSF Career Award (2009) and a Humboldt Fellowship (2016). In 2019, she was elected fellow of the American Physical Society.

Please email Alyssa Ramsey at a.ramsey@northeastern.edu for the link to the seminar.