Paper Number
BA8 

Session
Biological and Active Matters

Title
Viscosity of confined bacterial suspensions

Presentation Date and Time
October 15, 2018 (Monday) 2:20

Track / Room
Track 6 / Tanglewood

Authors (Click on name to view author profile)

1. Liu, Zhengyang (University of Minnesota, Chemical Engineering and Materials Science)
2. Narayan, Shweta (University of Minnesota, Mechanical Engineering)
3. Dutcher, Cari S. (University of Minnesota, Mechanical Engineering)
4. Zhang, Kechun (University of Minnesota, Chemical Engineering and Materials Science)
5. Cheng, Xiang (University of Minnesota, Chemical Engineering and Materials Science)

Author and Affiliation Lines (in printed abstract book)
Zhengyang Liu¹, Shweta Narayan², Cari S. Dutcher², Kechun Zhang¹, and Xiang Cheng^1
1Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455; ²Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455

Speaker / Presenter 
Liu, Zhengyang

Text of Abstract
Bacterial suspensions, a premier example of active fluids, show reduced viscosity compared to their counterpart colloidal suspensions. Bacterial “superfluid” with zero apparent viscosity has been shown in both bulk rheological measurements and bacterial “racetrack” experiments under strong confinement. These experiments suggest that geometry, in particular confinement, of systems plays an important role in modifying the viscosity of bacterial suspensions. Here, by adapting a microfluidic viscometer, we investigate the viscosity of bacterial suspensions in different confined geometries. We identified a strong confinement effect when the confinement length scale is below 50 microns, where the viscosity of bacterial suspensions decreases by a factor of 2.5, when the confinement decreases from 50 microns down to 25 microns. Above 50 microns, the viscosity of bacterial suspensions saturates and is independent of confinement. We further confirmed the result with a droplet based viscometer.