Actuation of water droplet on a simplified open-plate digital microfluids device with large electrode gaps

Date

4-2012

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Lou Serafin M. Lozada

Abstract

In this study, the effect of electrode array size on droplet actuation on an open-plate digital microfluidics device was investigated. Since droplet actuation basically works by the principle of electrowetting, static electrowetting was performed on .a 12.5-ilL water droplet from 50V to 1000 V. The droplet was placed in an electric field set up between a needle and a copper strip of different widths (w) - 0.3 mm, 0.6 mm, 1.0 mm, 1.5 mm, 2.0 mm, and 20.0 mm. The deformation, as measured by the change in contact angle, A cos 0, shows a good fit to the Lippmann-Young relation at voltages below 366.67±51.64 V. However, starting at 366.67±51.64 V saturation occurs. For w <1.0 mm, A cos °sat is larger and V1 is higher at larger w. In droplet actuation, a 12.5-4 droplet was transported by setting up an electric field between two adjacent coplanar electrodes with different w. The electrode array pitch was maintained at 2.3 mm. Droplet motion was examined by measuring the average speed, v, and change in lagging and leading contact angle, A cos 0/„, and A cos 0/eaci, from 100 V to 1000 V. Results show that at smaller width-to-pitch ratio and wider gap, the droplet moves faster, and full actuation is achieved at higher V without droplet trapping. In addition, the deformation is larger, as in static electrowetting. The highest v, 11.9 mm s-1, was observed using a 0.6-mm width at 700 V. With w >0.6 mm, the highest v was only 6.5 mm PACS: 47.20.Dr (Surface-tension-driven instability), 47.61.Ne (Micromixing)

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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