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Controlled Optofluidic Crystallization of Colloids Tethered at Interfaces
Alessio Caciagli1, Rajesh Singh2, Darshana Joshi1
1Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
Physical Review Letters
|August 27, 2020
Summary
Laser illumination rapidly crystallizes colloids at oil-water interfaces. This light-induced effect combines thermophoretic pumping and optical binding for novel colloidal assembly.
Area of Science:
- Colloid science
- Soft matter physics
- Optofluidics
Background:
- Colloidal particles at interfaces are crucial in various applications.
- Controlling colloidal self-assembly is a key challenge in materials science.
Purpose of the Study:
- To investigate light-induced crystallization of colloids at an oil-water interface.
- To understand the underlying mechanisms of laser-driven colloidal assembly.
Main Methods:
- Experiments involving colloids tethered to an oil-water interface.
- Application of laser illumination to induce changes in colloidal arrangement.
- Analysis of thermophoretic and optical forces acting on the colloids.
Main Results:
- Observed rapid crystallization of colloids upon laser illumination.
- Identified a combination of thermophoretic pumping and optical binding as the driving forces.
- Demonstrated that flow-induced forces can be described by a potential gradient.
- Showed that local heating leads to an effective equilibrium description of the nonequilibrium state.
Conclusions:
- Laser illumination provides a novel method for rapid colloidal crystallization.
- Optofluidic manipulation offers new possibilities for controlling and assembling colloidal particles.
- The findings open avenues for designing advanced materials and microdevices.
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