Materials Science

Fluorescent Staining of Silicone Micro-and Nano-patterns for Their Optical Imaging

Authors

Abstract

Performance of engineered surfaces can be enhanced by making them hydrophobic or superhydrophobic via coating them with low-surface-energy micro-and nano-patterns. However, the wetting phenomena of particularly irregular shape and spacing (super)hydrophobic patterns such as polysiloxane coatings are not yet fully understood from a microscopic perspective. Here, we show a new method to collect 3D confocal images from irregular polysiloxane micro-and nanorods from a single rod resolution to discuss their wetting response over long liquid/solid interaction times and quantify the length and diameter of these rods. To collect such 3D confocal images, fluorescent dye containing water droplets were left on our superhydrophobic and hydrophobic polysiloxane coated surfaces. Then their liquid/solid interfaces were imaged at different staining scenarios: (i) using different fluorescent dyes, (ii) when the droplets were in contact with surfaces, or (iii) after the droplets were taken away from the surface at the end of staining. Using such staining strategies, we could resolve the micro-and nanorods from root to top and determine their length and diameter, which were then found to be in good agreement with those obtained from their electron microscopy images. 3D confocal images in this paper, for the first time, present the long-time existence of more than one wetting state under the same droplet in contact with surfaces, as well as external and internal three-phase contact lines shifting and pinning. In the end, these findings were used to explain the time-dependent wetting kinetics of our surfaces. We believe that the proposed imaging strategy here will, in the future, be used to study many other irregular patterned (super)antiwetting surfaces to describe their wetting theory, which is today impossible due to the complicated surface geometry of these irregular patterns.

Content

Thumbnail image of Manuscript-Varol-Seeger-2021.pdf

Supplementary material

Thumbnail image of SI-Varol-Seeger-2021.pdf
Supplementary Data-Varol-Seeger-2021
Supplementary Data of the pre-print called "Fluorescent Staining of Silicone Micro-and Nano-patterns for Their Optical Imaging" written by Dr. H.Samet Varol and Prof. Stefan Seeger.
Thumbnail image of SI-Video1-Varol-Seeger-2021.mp4
Supplementary Video-S1
Supplementary Video presenting the confocal image of the hydrophobic surface after image analysis. The confocal image was taken when the surface was in contact with a water droplet containing Atto-COOH dyes (50µg/mL) inside.