title: Micropatterning for the control of surface cavitation: visualization through high-speed imaging.
abstract: For the first time, we apply a high-speed imaging technique to record the activity of acoustically driven cavitation bubbles (86 kHz) on micropatterned surfaces with hydrophobic and hydrophilic stripes. The width of the hydrophobic stripes lies between 3.5 and 115 μm. This work provides the first direct visualization of the preferential location of bubbles on the hydrophobic areas of the patterns. The results confirm our previous prediction that surface cavitation strongly depends on the surface energy of the irradiated substrate. The observations show a remarkable effect of the stripe width on the size, movement, growth, splitting, and multiplying of the bubbles. The high-speed imaging also reveals that there is a minimal width of the hydrophobic stripes that allows bubble attraction and formation. Our observations are supported by a theoretical approach based on the forces acting on the bubbles.
authors.affiliation: Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany.
authors.forename: Valentina
authors.initials: V
authors.lastname: Belova-Magri
authors.forename: Adam
authors.initials: A
authors.lastname: Brotchie
authors.forename: Carlos
authors.initials: C
authors.lastname: Cairós
authors.forename: Robert
authors.initials: R
authors.lastname: Mettin
authors.forename: Helmuth
authors.initials: H
authors.lastname: Möhwald
keywords: cavitation bubble; high-speed imaging; hydrophobic/hydrophilic surface; surface attached bubbles; surface cavitation; ultrasound