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Proceedings Paper

Optical systems based on electrowetting
Author(s): Frank Gindele; Frank Gaul; Thomas Kolling
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Paper Abstract

The optical application of electrowetting-on-dielectric (EWOD) using thin dielectric layers is the focus of this paper. An optical switching configuration is designed with transparent indium-tin-oxide (ITO) electrodes and glass substrates as well as a transparent dielectric film between the liquid and the electrodes. A polyimide layer with a thickness of 0.5 μm to 1.5 μm and a top coating of 0.5 μm PTFE as hydrophobic surface has been used as dielectric film. Experimentally we present a significant change in the contact angle up to 56° applying a voltage of 155 V. The wettability of the surface can be controlled and a liquid flow is achieved by applying a voltage below 100 V. The saturation of contact angle is described by a model including a contact angle dependent resistance of the dielectric layer as fitting parameter and a constant resistance of the water droplet. The resistances have been confirmed by independent measurements. Based on these results optical switching has been performed by the principle of total reflection. Thereby the refractive index of the optical beam path is changed between the total reflection condition at an interface and transmission. This operation is realised by moving a water droplet between two glass plates. Within this concept addressable operations of a liquid on a fluidic chip and the integration of optical guiding and switching of light is possible. The application of EWOD for optics can be fundamental for the integration of micro-optics and fluidics in one device and the development of new micro-opto-electro-mechanical systems (MOEMS).

Paper Details

Date Published: 16 August 2004
PDF: 12 pages
Proc. SPIE 5455, MEMS, MOEMS, and Micromachining, (16 August 2004); doi: 10.1117/12.543367
Show Author Affiliations
Frank Gindele, Institut fur Mikrotechnik Mainz GmbH (Germany)
Frank Gaul, Institut fur Mikrotechnik Mainz GmbH (Germany)
Thomas Kolling, Institut fur Mikrotechnik Mainz GmbH (Germany)

Published in SPIE Proceedings Vol. 5455:
MEMS, MOEMS, and Micromachining
Hakan Urey; Ayman El-Fatatry, Editor(s)

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