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Proceedings Paper

Graphene doped ZnO films for photoelectrowetting on microchannels
Author(s): Khaled Al-Aribe; George K. Knopf
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Paper Abstract

Photoelectrowetting on dielectric surfaces can be used to drive droplets of liquid along reconfigurable paths on a microfluidic chip using controlled optical signals. These electrostatically activated surfaces along the desired path eliminate the need for precision molded channels and discrete functional components such as microvalves and micropumps. The photoelectrowetting effect exploits the surface tension of the droplet to maintain its volume during the transportation pathway and the photoelectric properties of the substrate surface are used to induce reversible fluidic flow. The active light-driven substrate is structured from graphene doped zinc-oxide (ZnO-G) films deposited on ITO coated glass. This substrate is coated from the ZnO-G side with Ruthenium-based dye (N719) to maximize its absorbability. The light triggers two forces that enable the droplet to be transported along the substrate. The first arises from the induced hydrophobicity gradient formed across the droplet contact area with the substrate surface. Exposing the ZnO-G film to a broad spectrum white light source alters the surface’s electric potential which induces a change in the droplet’s contact angle and the associated hydrophobicity. Once the hydrophobicity gradient is generated the droplet will start to move in the direction of the wetting zone. The second force is also created by the optical input when the absorbed light generates a photoelectric potential that produces a piezo-electrical effect on the ZnO-G film. The light triggered piezo-electrical behavior of the ZnO-G film can be used to generate the erasable microchannels that can guide droplet movement through a microfluidic chip. Preliminary experiments are performed to investigate the photoelectric potential of light activated ZnO-G films.

Paper Details

Date Published: 28 February 2017
PDF: 8 pages
Proc. SPIE 10061, Microfluidics, BioMEMS, and Medical Microsystems XV, 1006105 (28 February 2017); doi: 10.1117/12.2252148
Show Author Affiliations
Khaled Al-Aribe, Abu Dhabi Univ. (United Arab Emirates)
George K. Knopf, The Univ. of Western Ontario (Canada)

Published in SPIE Proceedings Vol. 10061:
Microfluidics, BioMEMS, and Medical Microsystems XV
Bonnie L. Gray; Holger Becker, Editor(s)

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