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The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids
Published on: September 30, 2014
Dynamic electrowetting-on-dielectric (DEWOD) on unstretched and stretched teflon
Min Wook Lee1, Sanjay S Latthe, Alexander L Yarin
1School of Mechanical Engineering, Korea University, Seoul 136-713, Korea.
Langmuir : the ACS Journal of Surfaces and Colloids
|May 28, 2013
Summary
Dynamic electrowetting on dielectric (DEWOD) was studied using stretched and unstretched Teflon surfaces during water drop impacts. Applying voltage significantly reduced superhydrophobicity, enabling control over water drop behavior for applications like microfluidics.
Area of Science:
- Materials Science
- Surface Science
- Fluid Dynamics
Background:
- Electrowetting-on-dielectric (EWOD) typically involves static conditions and standard capacitance.
- Dynamic EWOD (DEWOD) presents unique challenges due to changing capacitance during impact.
- Hydrophobic surfaces like Teflon are crucial for water-repellent applications.
Purpose of the Study:
- To investigate the dynamic electrowetting behavior of water drops on unstretched and stretched Teflon surfaces.
- To analyze the effect of surface strain and electrical potential on water droplet impact and rebound.
- To explore the potential of DEWOD for controlling liquid behavior in dynamic scenarios.
Main Methods:
- Experimental investigation of deionized water drop impact and rebound on unstretched and stretched Teflon (up to 250% strain).
- Measurement of surface roughness and equilibrium water contact angles.
- Application of electrical potential to induce electrowetting and analysis of dynamic responses.
Main Results:
- Stretching Teflon increased surface roughness and equilibrium contact angle, enhancing superhydrophobicity.
- DEWOD significantly reduced superhydrophobicity on both surfaces upon voltage application.
- Stretched Teflon exhibited a sharper DEWOD response, with a 3 kV potential causing water drops to adhere, while unstretched Teflon still showed partial rebound.
Conclusions:
- Dynamic electrowetting offers a powerful method to actively control superhydrophobic surfaces.
- Strained hydrophobic surfaces show enhanced DEWOD effects, allowing for precise manipulation of liquid behavior.
- DEWOD has potential applications in spray cooling, painting, coating, and microfluidic drop transport.
