Surface Modification of 3D Printed Microfluidic Devices for Controlled Wetting in Two-Phase Flow.

Area of Science:

• Materials Science
• Chemical Engineering
• Microfluidics

Background:

• 3D-printed microfluidic devices (MFDs) often lack surface hydrophobicity, leading to issues like droplet adhesion and aqueous spreading.
• This limits their utility in applications such as droplet microfluidics and lab-on-a-chip systems.

Purpose of the Study:

• To develop an effective post-processing technique to enhance the surface hydrophobicity of 3D-printed MFDs.
• To improve the performance of MFDs in microfluidic applications by reducing unwanted droplet interactions.

Main Methods:

• A post-processing method involving flowing hydrophobic monomers into MFD channels without initiator.
• Subsequent UV light exposure to initiate polymerization of surface-bound monomers, leveraging residual initiators from the initial 3D printing process.
• Surface characterization using contact angle measurements to quantify hydrophobicity.

Main Results:

• The post-processing technique significantly increased the hydrophobicity of MFD surfaces, evidenced by higher contact angles.
• Treatment with alkyl acrylates and fluorinated acrylates yielded the most hydrophobic surfaces.
• The method successfully prevented bulk polymerization within the channels, maintaining device functionality.

Conclusions:

• A fast, easy, and effective post-processing method was established to impart significant hydrophobicity to 3D-printed MFDs.
• This technique enhances MFD performance by mitigating droplet adhesion and aqueous spreading.
• The approach is versatile and can be adapted for surface modification with various monomers to achieve tailored channel characteristics.