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Actuation of Flexible Membranes via Capillary Force: Single-Active-Surface Experiments

Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904, USA
Author to whom correspondence should be addressed.
Micromachines 2018, 9(11), 545;
Received: 20 September 2018 / Revised: 11 October 2018 / Accepted: 23 October 2018 / Published: 25 October 2018
(This article belongs to the Special Issue Microscale Surface Tension and Its Applications)
PDF [1962 KB, uploaded 25 October 2018]


Conventional approaches to microscale actuation, such as electrostatic, have difficulty in achieving large motion at moderate voltages. Recently, actuators relying on the active control of capillary pressure have been demonstrated, with the pressure change caused by electrowetting on a pair of opposing surfaces. In this work, experimental results are presented from five prototype devices in which only a single active surface is used. The results demonstrate that pressure changes induced in a liquid bridge in this manner can produce large deflections (15 μm) of a flexible membrane. Voltages employed in the tests were moderate (≤25 V). The influence of several design variables, such as membrane diameter and thickness, on the membrane deflection are examined. Theoretical predictions are also presented and generally follow the experimental values. Potential sources for the discrepancies between theory and experimental results are discussed. While deflections obtained using a single active surface are not as large as those obtained with two active surfaces, single-active-surface configurations offer a simple route to achieving adequate deflections for lab-on-a-chip microsystems. View Full-Text
Keywords: electrowetting; actuation; capillary pressure; lab-on-a-chip electrowetting; actuation; capillary pressure; lab-on-a-chip

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Barth, C.; Knospe, C. Actuation of Flexible Membranes via Capillary Force: Single-Active-Surface Experiments. Micromachines 2018, 9, 545.

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