The paper reports on wetting, electrowetting (EW), and systematic contact angle hysteresis measurements after electrowetting of superhydrophobic silicon nanowire surfaces (NWs). The surfaces consist of C4F8-coated silicon nanowires grown on Si/SiO2 substrate. Different surfaces modulating (i) the dielectric layer thickness and (ii) the nanotexturation were investigated in this study. It was found that the superhydrophobic NWs display different EW behaviors according to their double nanotexturation with varying droplet impalement levels. Some surfaces exhibited a total reversibility to EW with no impalement (contact angle variation of 35+/-2 degrees at 190 VTRMS with deionized water), whereas other surfaces showed nonreversible behavior to EW with partial droplet impalement. A scenario is proposed to explain the unique properties of these surfaces.
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http://dx.doi.org/10.1021/la803756f | DOI Listing |
J Colloid Interface Sci
October 2024
Micro- and Nanotechnology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China.
Hypothesis: Electrowetting on conventional dielectrics requires direct fluid-electrode contact to generate strong electric fields at the three-phase contact line to modulate the wetting. Since the electric field alters wetting, the modulation of wetting can be achieved by applying an external electric field through insulated electrodes, preventing the liquid from contacting the electrodes.
Experiment: A simple and efficient method for non-contact between the fluid and the electrode external electric field modulation of fluid wetting was proposed.
Sci Rep
May 2024
Institute of Applied Mechanics, National Taiwan University, No.1, Sec. 4, Roosevelt Rd., Da'an Dist., Taipei City, 106, Taiwan (R.O.C.).
In this study, we experimentally identify the effect of liquid dielectrophoresis (LDEP) force on a superhydrophobic surface in directing the trajectory of moving water droplets across designed interdigitated electrodes and show that this method is capable of rapidly selecting droplets at a high speed (200 mm/s). As the droplets traverse down the surface by the electric field, their deflection on the edge of these electrodes is achieved successively, allowing for the selective manipulation of discrete droplets. A series of experiments were conducted to validate the relationships among droplet deflections, applied electric fields, and dynamic contact angles.
View Article and Find Full Text PDFAdv Mater
June 2024
Cancer Hospital of Dalian University of Technology (Liaoning Cancer Hospital & Institute), Shenyang, 110042, P. R. China.
Nanomaterials (Basel)
June 2022
Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany.
Digital microfluidics (DMF) is a versatile platform for conducting a variety of biological and chemical assays. The most commonly used set-up for the actuation of microliter droplets is electrowetting on dielectric (EWOD), where the liquid is moved by an electrostatic force on a dielectric layer. Superhydrophobic materials are promising materials for dielectric layers, especially since the minimum contact between droplet and surface is key for low adhesion of biomolecules, as it causes droplet pinning and cross contamination.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2022
Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23221, USA.
Correction for 'Reversible electrowetting transitions on superhydrophobic surfaces' by D. Vanzo , , 2021, , 27005-27013, DOI:10.1039/D1CP04220C.
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