Indexed by:期刊论文

Date of Publication:2021-01-28

Journal:MICRO & NANO LETTERS

Volume:13

Issue:7

Page Number:896-901

ISSN No.:1750-0443

Key Words:water; drops; two-phase flow; pipe flow; hydrophobicity; etching; electrochemistry; contact angle; capillarity; reversible lossless manipulation; water droplets; microdroplets; liquid transportation; superhydrophobic surfaces; adhesion; transfer pipette; superhydrophobic hole; pressure-generation device; electrochemical etching; boiling-water immersion; stearic acid modification; water contact angle; roll-off angle; capillary force; gravity; biological field; microfluidic field; H2O

Abstract:The lossless manipulation of microdroplets has great promising applications in the fields of such as liquids transportation. In recent years, superhydrophobic surfaces with low adhesion have been utilised as an effective solid surface to realise the lossless transfer of liquids. However, the present methods using superhydrophobic surfaces are hard to realise the reversible lossless manipulation of water droplets with a large-range volume. Here, a special transfer pipette composed of a superhydrophobic hole and an optimised pressure-generation device is developed to realise the lossless manipulation of water droplets. The superhydrophobic surfaces are obtained by electrochemical etching, boiling-water immersion and stearic acid modification, showing an excellent superhydrophobicity with a water contact angle of approximate to 165 degrees and roll-off angle of approximate to 2 degrees. The capture and release of water droplets are realised via controlling the resultant force of the vertical component of capillary force and gravity of droplets. The applied pressure is far less than the threshold pressure which guaranties the lossless property in the manipulation processes. The operable limiting volume of water droplets even reaches to 1404 mu L, showing a large-range operable volume. Moreover, the strategy can easily realise the reversible and repeatable manipulation showing potential applications in the biological and microfluidic fields.