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Updated: Aug 10, 2026
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On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids
Published on: March 2, 2012
Stability of charge inversion, Thomson problem, and application to electrophoresis
Michael Patra1, Marco Patriarca, Mikko Karttunen
1Biophysics and Statistical Mechanics Group, Laboratory for Computational Engineering, Helsinki University of Technology, P.O. Box 9203, FIN-02015 HUT, Finland.
Summary
Colloidal systems with microions exhibit overcharging, forming stable, low-energy states. This stability is reduced by electric fields, with implications for multi-colloid systems.
Area of Science:
- Colloid and Interface Science
- Statistical Mechanics
- Condensed Matter Physics
Background:
- Charge inversion is a key phenomenon in colloidal systems.
- The Thomson problem addresses optimal microion arrangement on a sphere.
- Understanding microion behavior is crucial for colloid stability.
Purpose of the Study:
- To analyze charge inversion in colloidal systems at zero temperature.
- To connect colloidal charge inversion to the Thomson problem.
- To investigate microion layer stability and behavior under electric fields.
Main Methods:
- Stability analysis of colloidal systems.
- Application of concepts from the Thomson problem.
- Investigation of microion arrangements and energy states.
Main Results:
- Globally stable, lowest-energy states are always overcharged for finite microion charge.
- A layer at least twice the charge-neutral amount of microions is locally stable.
- Applied electric fields reduce the stability of the microion cloud.
Conclusions:
- Charge inversion in colloids leads to overcharging in stable states.
- Microion layer stability is a significant factor in colloidal complex formation.
- The study provides insights into multi-colloid systems at finite temperatures.
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