Related Experiment Video
Updated: Mar 27, 2026
07:57
Taking Advantage of Reduced Droplet-surface Interaction to Optimize Transport of Bioanalytes in Digital Microfluidics
Published on: November 10, 2014
8.4K
Motility of active fluid drops on surfaces
Diana Khoromskaia1, Gareth P Alexander1
1Department of Physics and Centre for Complexity Science, University of Warwick, Coventry CV4 7AL, United Kingdom.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|January 15, 2016
Summary
Active liquid crystal drops self-propel due to topological defects. Asymmetric orientation profiles and surface friction control their movement and speed on planar surfaces.
Area of Science:
- Physics
- Materials Science
- Fluid Dynamics
Background:
- Active liquid crystals exhibit self-propulsion.
- Motility is linked to topological defects in filament orientation.
Purpose of the Study:
- Investigate the onset and aspects of motility in 3D active fluid drops on a planar surface.
- Analyze the influence of orientation profiles, drop shape, and surface friction on self-propulsion.
Main Methods:
- Theoretical analysis of active fluid drops.
- Derivation of exact flow expressions within a thin drop approximation.
- Decomposition of flow into geometrical and shape-coupling terms.
Main Results:
- Asymmetric splay or bend in orientation profiles drives directed bulk flow and motility.
- Maximal speeds are achieved with topological defects inducing splay or bend.
- Friction at the substrate dictates self-propulsion direction and speed.
Conclusions:
- Topological defects and asymmetric orientation profiles are key to active drop motility.
- Drop shape and surface friction are critical parameters for controlling self-propulsion.
- This work provides a theoretical framework for understanding active fluid drop dynamics.
Related Concept Videos
01:22Surface Tension of Fluid
1.9K
Surface tension is a fundamental property of fluids, occurring at the boundary between a liquid and a gas or between two immiscible liquids. This phenomenon arises from the cohesive forces between molecules at the fluid's surface, creating an effect similar to a stretched elastic membrane. Inside each fluid, molecules are equally attracted in all directions by neighboring molecules, but surface molecules experience a net inward force, resulting in surface tension.
Surface tension varies...
Surface tension varies...
1.9K
02:57Surface Tension, Capillary Action, and Viscosity
34.5K
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
34.5K
01:19Capillarity in Fluid
1.5K
Capillarity describes the movement of liquid in small spaces without external forces acting on it. The capillarity is driven by surface tension and adhesive interactions between the liquid and surrounding solid surfaces. This effect is often seen in narrow tubes, porous materials, and fine particles.
Surface tension is crucial to capillarity. It results from cohesive forces between liquid molecules at the liquid-air boundary, forming a skin that resists external forces. When the capillary tube...
Surface tension is crucial to capillarity. It results from cohesive forces between liquid molecules at the liquid-air boundary, forming a skin that resists external forces. When the capillary tube...
1.5K
01:17Viscosity
7.9K
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
7.9K
01:27Surface Active Agents
113
Surfactants, named for their behavior at interfaces, positively adsorb at the interfaces of two phases, reducing interfacial tension. Their versatility as emulsifiers, detergents, and foaming agents stems from this ability. Surfactants, often termed amphiphiles, share the property of amphipathy, with molecules having both hydrophilic and hydrophobic portions. The hydrophilic part is called the head, and the hydrophobic part, including an elongated alkyl substituent, forms the tail.Surfactants...
113
01:18Rise of Liquid in a Capillary Tube
3.4K
When very thin cylindrical tubes, called capillaries, are dipped in a liquid, the liquid rises or falls in the tube compared to the surrounding liquid. This phenomenon is called capillary action. Capillary action occurs due to the combination of two opposing forces: the cohesive forces of the liquid, which cause it to stick to itself and form a rounded shape, and the adhesive forces between the liquid and the walls of the container, which cause the liquid to be attracted to the container walls.
3.4K