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Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
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Oscillating modes of driven colloids in overdamped systems
Johannes Berner1,2, Boris Müller3,4, Juan Ruben Gomez-Solano1,2
12. Physikalisches Institut, Universität Stuttgart, D-70569, Stuttgart, Germany.
Nature Communications
|March 10, 2018
Summary
Colloidal particles in viscoelastic fluids exhibit unexpected oscillations due to fluid non-equilibrium fluctuations. This finding impacts how colloidal probe experiments are interpreted and broadens their use as model systems.
Area of Science:
- Soft matter physics
- Colloidal science
- Biophysics
Background:
- Microscopic colloidal particles in liquids often model overdamped systems.
- Colloids serve as sensitive probes in biophysical applications to infer molecular forces.
- Current interpretations assume fluid equilibrium during driven colloidal experiments.
Purpose of the Study:
- To experimentally investigate particle dynamics in viscoelastic fluids.
- To challenge the assumption of fluid equilibrium in driven colloidal systems.
- To characterize novel oscillatory dynamics in colloidal suspensions.
Main Methods:
- Experimental observation of microscopic colloidal particles in viscoelastic fluids.
- Application of small driving forces to the colloidal particles.
- Analysis of particle oscillations using an overdamped Langevin equation.
Main Results:
- Observed particle oscillations with durations of several tens of seconds, even at small driving forces.
- Attributed oscillations to non-equilibrium fluid fluctuations excited by particle motion.
- Demonstrated quantitative agreement between experimental data and a modified Langevin equation.
Conclusions:
- The assumption of fluid equilibrium is invalid for driven colloidal particles in viscoelastic fluids.
- Observed oscillatory dynamics can be modeled as a stochastically driven underdamped oscillator.
- These findings necessitate re-evaluation of colloidal probe experiments and expand colloid applications.
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