Light-Triggered Manipulations of Droplets All in One: Reversible Wetting, Transport, Splitting, and Merging.

Area of Science:

• Soft Matter Physics
• Surface Science
• Materials Science

Background:

• Controlling microdroplet behavior is crucial for various applications.
• Existing methods often lack precision or require complex setups.

Purpose of the Study:

• To develop a novel method for light-triggered microdroplet manipulation.
• To explore reversible changes in wetting properties using photoswitchable films.

Main Methods:

• Utilizing adaptive films with azobenzene-containing surfactants.
• Employing optical stimuli to induce photoisomerization and surface energy changes.
• Investigating droplet behavior including wetting, splitting, merging, and transport.

Main Results:

• Demonstrated reversible wetting, droplet splitting, merging, and transport.
• Achieved reversible increase in droplet basal area up to 5 times.
• Showcased droplet locomotion up to 150 μm·s⁻¹ using a moving light spot.

Conclusions:

• Developed a versatile platform for precise microdroplet manipulation using light.
• The findings pave the way for programmable microfluidic workbenches.
• This technique offers a gentle and efficient method for controlling microdroplets.