Ultrafast bounce of particle-laden droplets

Area of Science:

• Fluid Dynamics
• Materials Science
• Surface Science

Background:

• Liquid droplet rebound on surfaces mimics elastic spheres but has unique contact dynamics.
• Existing methods to reduce droplet contact time are limited to milliseconds due to capillary effects.
• Rapid droplet detachment is crucial for numerous industrial and scientific applications.

Purpose of the Study:

• To achieve ultrafast rebound of liquid droplets with significantly reduced contact times.
• To investigate the underlying mechanisms of contact time reduction in droplet-surface interactions.
• To develop a versatile strategy for controlling solid-liquid composite system dynamics.

Main Methods:

• Designed heterogeneous core-shell droplets encapsulating a particle (DEP).
• Investigated droplet rebound dynamics on various surfaces (polydimethylsiloxane, glass).
• Conducted systematic experimental and analytical studies across different impact velocities and systems.

Main Results:

• Achieved unprecedentedly short contact times of 0.3 ms and 0.05 ms with polydimethylsiloxane and glass, respectively.
• Demonstrated universal applicability across diverse systems: water/oil droplets, elastic/rigid particles, super-repellent/superlyophilic surfaces.
• Observed solid-like behavior in DEP due to synchronized particle-droplet motion, overcoming capillary dominance.

Conclusions:

• DEP technology enables ultrafast liquid droplet rebound by breaking capillary dominance.
• The study delineates three bouncing regimes and identifies conditions for regime transitions.
• DEP offers a robust strategy for tailoring contact time in solid-liquid composite systems.