Pattern Formation by Staphylococcus epidermidis via Droplet Evaporation on Micropillars Arrays at a Surface

Area of Science:

• Materials Science
• Microbiology
• Fluid Dynamics

Background:

• Evaporation of droplets containing microorganisms like Staphylococcus epidermidis (S. epidermidis) results in complex deposition patterns.
• Surface microstructuring can influence these evaporation dynamics and deposition patterns.

Purpose of the Study:

• To investigate the effect of epoxy surface structuring on the evaporation of S. epidermidis-laden water droplets.
• To understand how microstructured surfaces influence bacterial deposition patterns and viability.

Main Methods:

• Fabrication of epoxy surfaces with varying microstructures.
• Observation and analysis of water droplet evaporation and S. epidermidis deposition patterns.
• Modeling capillary flows during evaporation using polystyrene particles.
• Bacterial viability measurements of S. epidermidis.

Main Results:

• Droplet evaporation on microstructured surfaces leads to distinct deposition patterns (e.g., octagonal, square) influenced by microstructure height.
• The interplay between zipping-wetting and coffee-stain effects dictates S. epidermidis distribution.
• High viability of planktonic S. epidermidis was observed, but biomass deposition on microstructured surfaces was low.

Conclusions:

• Surface microstructuring significantly controls the spatial distribution and deposition of S. epidermidis during droplet evaporation.
• Findings provide design principles for microstructured surfaces to manage bacterial propagation, potentially reducing biocide use.