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Patterning of Microorganisms and Microparticles through Sequential Capillarity-assisted Assembly
Published on: November 4, 2021
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Dielectrophoretic assembly of dimpled colloids into open packing structures.
Zhuoqiang Jia1, Stefano Sacanna, Stephanie S Lee
1Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ, USA. stephanie.lee@stevens.edu.
Soft Matter
|August 1, 2017
Summary
Two-dimensional colloidal crystals exhibit reversible phase transitions between open and close-packed structures. Applied electric fields control lattice symmetry and packing fraction, demonstrating tunable self-assembly in colloidal systems.
Area of Science:
- Colloidal science
- Soft matter physics
- Materials science
Background:
- Colloidal crystals are model systems for studying phase transitions.
- Controlling the assembly of colloidal particles is crucial for developing novel materials.
- Understanding interparticle forces is key to predicting and manipulating self-assembly.
Purpose of the Study:
- To investigate reversible solid-state phase transitions in two-dimensional colloidal crystals.
- To explore the effect of electric fields on lattice structure and packing fraction.
- To elucidate the mechanisms driving the observed phase transitions.
Main Methods:
- Utilized negative dielectrophoresis to manipulate 1.8 μm dimpled spherical colloids.
- Employed finite Fourier transform analysis to study lattice dynamics.
- Conducted COMSOL simulations to model interparticle interactions and electric field effects.
Main Results:
- Observed reversible transitions between open (cmm symmetry, ϕ=0.68) and close-packed (p6m symmetry, ϕ=0.90) structures.
- Identified repulsive forces perpendicular to electric field lines, caused by field concentration at colloid edges.
- Demonstrated that lattice stretching magnitude correlates with electric field strength.
Conclusions:
- Applied electric fields can reversibly tune the structure and packing of 2D colloidal crystals.
- The observed transitions are driven by electric field-induced interparticle repulsions.
- Entropically favored close-packed structures can be recovered by screening colloids from the electric field.
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