Nis elements advanced research microscope imaging software

An oxygen plasma cleaner (Harrick plasma cleaner PDC-32G) was used to oxidize the surface and change the wettability of 1.5 mm PMMA particles. Cleaned particles were treated with oxygen plasma for 5 minutes to increase the surface hydrophilicity. The changed wettability of the particles was manifested as a change in the fraction of the particle immersed when placed on the subphase.
To measure the immersed depth of a PMMA particle, it was gently placed at the water/vapor interface in a square glass cuvette (2 cm × 2 cm). A solid state camera (Cohu, model #4115-5000-0000) with a zoom objective (Bausch and Lomb Monozoom 7) was focused at the three-phase contact line around the particle periphery, with illumination from behind the cuvette. Captured images were analyzed (Nikon NIS-Elements Advanced Research microscope imaging software) to determine the immersed depth of particle, the distance from the interface where liquid meets the particle to the bottom of the particle. The immersed depths, of untreated 0.5 mm, 1.5 mm and 3.2 mm particles in water were 0.32 ± 0.02 mm, 0.86 ± 0.04 mm and 1.8 ± 0.1 mm, respectively. The immersed depth of the plasma treated 1.5 mm particle in water was 1.4 ± 0.1 mm.