Reversible wetting of titanium dioxide films

A. G.G. Toh, M. G. Nolan, R. Cai, D. L. Butler

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

4 Citations (Scopus)

Abstract

Titanium dioxide (TiO2) films were rendered hydrophilic through ultraviolet (UV) light irradiation (254nm) and returned to their previous hydrophobic condition when exposed to a sealed pressurized nitrogen atmosphere. UV light irradiation on TiO2 films resulted in super-hydrophilic surfaces with water contact angles of <5°. Alternatively, exposure of the films to an N2 environment resulted in relatively hydrophobic surfaces with water contact angles of >40°. The switching of TiO 2 surface wettability could be repeated on the same surface with little hysteresis in water contact angle values. The mechanism behind the hydrophilic and hydrophobic reversal in TiO2 surfaces is proposed to be due to UV light mediated photocatalysis and physio- adsorption of N 2 molecules respectively. The non-intrusive control of TiO 2 surface wettability could be an attractive alternative to other wettability-based microfluidic valving strategies like electrowetting and photochromic wetting variation. The above results are discussed in terms of the potential use of the films in wettability based valving and repeated wettability patterning of TiO2 surfaces for open and sealed microfluidic systems.

Original languageEnglish
Title of host publicationProc. SPIE 6800, Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV
Place of PublicationBellingham, Washington
Volume6800
DOIs
Publication statusPublished - 2008
Externally publishedYes
EventDevice and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV - Canberra, Australia
Duration: 5 Dec 20077 Dec 2007

Conference

ConferenceDevice and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV
CountryAustralia
CityCanberra
Period5/12/077/12/07

Keywords

  • hydrophilicity
  • hydrophobicity
  • microfluidics
  • N
  • photocatalysis
  • titanium dioxide

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    Toh, A. G. G., Nolan, M. G., Cai, R., & Butler, D. L. (2008). Reversible wetting of titanium dioxide films. In Proc. SPIE 6800, Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV (Vol. 6800). [680004]. https://doi.org/10.1117/12.759438