Formation of surface nanodroplets facing a structured microchannel wall.

Area of Science:

• Microfluidics
• Surface Science
• Nanotechnology

Background:

• Surface nanodroplets are crucial for lab-on-a-chip devices and catalytic reactions.
• Solvent exchange in microchannels is a common method for producing these nanodroplets.
• Controlling nanodroplet size and distribution is key for their applications.

Purpose of the Study:

• To investigate the impact of microfluidic structures on surface nanodroplet formation.
• To understand how microgap geometry influences nanodroplet characteristics.
• To explore methods for controlling nanodroplet size and spatial organization.

Main Methods:

• Simulations of fluid flow and oversaturation profiles within microchannels.
• Fabrication of microfluidic devices with embedded microgaps.
• Analysis of surface nanodroplet size and distribution under varying flow conditions and microgap geometries.

Main Results:

• Microgaps enhance nanodroplet volume and create asymmetric spatial distributions.
• The Peclet number (Pe) significantly affects droplet distribution and size scaling.
• Microgap dimensions (height and aspect ratio) influence droplet size at constant Pe.

Conclusions:

• Local microfluidic structures provide effective control over surface nanodroplet formation.
• Microgap-induced flow patterns are responsible for observed nanodroplet characteristics.
• This approach enables precise bottom-up control of nanodroplet size and organization on surfaces.