A Laboratory Experiment to Demonstrate the Principles of Sedimentation in a Centrifuge: Estimation of Radius and Settling Velocity of Bacteria


  • Erin Riley Northwestern University • Evanston, IL 60208
  • P. Arthur Felse Northwestern University • Evanston, IL 60208


Centrifugation is a major unit operation in chemical and biotechnology industries. Here we present a simple, hands-on laboratory experiment to teach the basic principles of centrifugation and to explore the shear effects of centrifugation using bacterial cells as model particles. This experiment provides training in the use of a bench-top centrifuge, handling of bacterial cells, and data analysis. Advanced pedagogical elements in this experiment include team skills coaching and the use of electronic lab notebooks. Several cognitive conflicts presented by centrifugation data fosters critical thinking and stimulates learning by prompting students to look beyond immediately apparent conclusions. 

Author Biographies

Erin Riley, Northwestern University • Evanston, IL 60208

Erin Riley graduated with a B.S. in microbiology and French horn performance from the University of Wisconsin-Madison. She spent 6 years as a research specialist at UW-Madison, where her efforts have contributed greatly to several publications in journals such as Endocrinology and Journal of Biological Chemistry. She then joined the Masters of Biotechnology program at Northwestern University where she ran the teaching lab. She is currently working at Catalent Pharmaceuticals in the Quality Control department.

P. Arthur Felse, Northwestern University • Evanston, IL 60208

Arthur Felse is a lecturer in the Master of Biotechnology Program, and in the Department of Chemical & Biological Engineering at Northwestern University. He is also the assistant director for research in the Master of Biotechnology Program. His research interests include engineering education, diversity in engineering, and biotech regulatory sciences. Arthur is actively involved in ASEE where he served as the chemical engineering division program chair for the 2016 Annual Conference. He also served as a faculty in the 2012 ChE Summer School.