Indexed by:期刊论文

Date of Publication:2019-01-29

Journal:LANGMUIR

Included Journals:SCIE、PubMed、Scopus

Volume:35

Issue:4

Page Number:935-942

ISSN No.:0743-7463

Key Words:Anisotropy; Controlled drug delivery; Drops; End effectors; Targeted drug delivery, Chemical oxidation; Droplet manipulation; Fluorocarbon film deposition; Hydrophobic patterns; Lab-on-chip devices; Molecular detection; Patterned surface; Sliding resistance, Hydrophobicity

Abstract:Superhydrophobic copper surfaces patterned with non-round hydrophobic areas were fabricated by a combination of through-mask chemical oxidation and fluorocarbon film deposition techniques. The anisotropic sliding resistance of droplets on typical non-round hydrophobic patterns such as semicircle, V-shape, and line segment hydrophobic patterns was observed. The dependence of sliding anisotropy on the pattern shape and dimensions was investigated. Results showed that the experimental sliding resistance was in good agreement with the calculated data using a classical drag resistance model (Furmidge equation). By taking advantage of the anisotropic sliding resistance, these patterned surfaces can be used as droplet mechanical hands to capture, transfer, mix, and release in situ micro droplets by simply moving the surfaces in different directions. A droplet pinned on a non-round hydrophobic pattern can be captured by lifting a surface with another non-round hydrophobic pattern in a large-sliding-resistance direction after touching it, while the captured droplet can be released in situ with nearly no mass loss by horizontally moving the surface in the low-sliding-resistance direction. The lossless droplet manipulations using hydrophobic/superhydrophobic patterned surfaces have advantages of being low in cost and easy to operate and may have great promising applications to high throughput drug screening, molecular detection, and other lab-on-chip devices.