Droplet Misalignment Limit for Inkjet Printing into Cavities on Textured Surfaces

Area of Science:

• Fluid Dynamics
• Surface Science
• Computational Physics

Background:

• Controlling droplet deposition on textured surfaces is crucial for engineering and medical applications.
• Understanding droplet behavior in confined spaces, especially under misalignment, is key to improving print quality.

Purpose of the Study:

• Investigate droplet deposition dynamics in confined spaces.
• Analyze the impact of print head misalignment, nonuniform wettability, and droplet size on final morphology and print quality.
• Determine optimal conditions for droplet self-alignment and cavity filling.

Main Methods:

• Utilized a multiphase pseudopotential lattice Boltzmann methodology for simulation.
• Characterized print quality using the wetted fraction parameter.
• Examined effects of single and multiaxis misalignment, varying wettabilities, and droplet sizes.

Main Results:

• Multiaxis misalignment led to a higher wetted fraction compared to single-axis misalignment.
• Larger ratios of contact angles between substrate and cavity walls enhanced droplet self-alignment.
• Uniform wettabilities were identified that mitigate misalignment effects.
• Larger droplets can compensate for misalignment, and limits for single-drop cavity filling were defined.
• Cavity spacing is critical for determining maximum permissible misalignment in closely positioned cavities.

Conclusions:

• Droplet deposition dynamics are significantly influenced by misalignment, wettability, and droplet size.
• Strategies involving multiaxis misalignment, specific contact angle ratios, and optimized droplet sizes can enhance print quality.
• Cavity spacing plays a vital role in managing misalignment in multi-cavity deposition.