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Updated: Jun 5, 2026
22:38
Chemotactic Response of Marine Micro-Organisms to Micro-Scale Nutrient Layers
Published on: May 28, 2007
Oscillatory flows induced by microorganisms swimming in two dimensions
Jeffrey S Guasto1, Karl A Johnson, J P Gollub
1Department of Physics, Haverford College, Haverford, Pennsylvania 19041, USA.
Physical Review Letters
|January 15, 2011
Summary
We measured the flow patterns created by swimming green algae (C. reinhardtii). The algae generate complex, time-dependent flows, requiring significantly more energy than steady swimming.
Area of Science:
- Microfluidics
- Biophysics
- Fluid Dynamics
Background:
- Understanding the fluid dynamics of microorganisms is crucial for fields like microfluidics and biophysics.
- Previous studies lacked detailed, time-resolved measurements of the flow fields generated by individual swimming cells.
Purpose of the Study:
- To present the first time-resolved measurements of the oscillatory velocity field induced by swimming unicellular microorganisms.
- To quantify the mechanical power output and energy dissipation of these microorganisms.
Main Methods:
- Confinement of Chlamydomonas reinhardtii in stabilized thin liquid films.
- Simultaneous tracking of algal cells and surrounding tracer particles.
- Analysis of time-resolved velocity fields to determine flow structures and power generation.
Main Results:
- Complex, time-dependent flow structures were observed, scaling inversely with distance from the cell.
- Instantaneous mechanical power generated by the cells was measured, peaking at 15 fW.
- Energy dissipation per cycle was found to be over four times that required for steady swimming.
Conclusions:
- Swimming microorganisms create intricate flow fields with significant energy dissipation.
- These findings provide new insights into the hydrodynamics and energy budget of microbial swimmers.
- The study highlights the energetic cost of unsteady swimming in unicellular organisms.
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