Manipulated wettability of a superhydrophobic quartz crystal microbalance through electrowetting

K D Esmeryan, G McHale, C L Trabi, N R Geraldi, M I Newton

Research output: Contribution to journalArticlepeer-review

Abstract

The liquid phase response of quartz crystal microbalances (QCM) with a thin coating (~9 µm) of epoxy resin with and without a carbon nanoparticles top layer is reported. The nanoparticles convert the epoxy surface to a superhydrophobic one with a high static contact angle (~151º-155º) and low contact angle hysteresis (~1º-3.7º) where droplets of water are in the suspended Cassie-Baxter state. The frequency decrease of the fully immersed QCM with the superhydrophobic surface is less than with only epoxy layer, thus indicating a decoupling of the QCM response. A wettability transition to a liquid penetrating into the surface roughness state (for droplets a high contact angle hysteresis Wenzel state) was triggered using a molarity of ethanol droplet test (MED) and electrowetting; the MED approach caused some surface damage. The electrowetting induced transition caused a frequency decrease of 739 Hz at a critical voltage of ~100 V compared to the QCM in air. This critical voltage correlates to a contact angle decrease of 26º and a high contact angle hysteresis state in droplet experiments. These experiments provide a proof-of-concept that QCMs can be used to sense wetting state transitions and not only mass attachments or changes in viscosity-density products of liquids.
Original languageEnglish
Pages (from-to)345307
Number of pages1
JournalJournal of Physics D: Applied Physics
Volume46
Issue number34
DOIs
Publication statusPublished - 9 Aug 2013

Keywords

  • electrowetting
  • superhydrophobic
  • slip
  • QCM
  • quartz crystal microbalance
  • acoustic wave

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