AC Electrowetting of Polymer Aqueous Drops on Parallel Electrodes

ORAL

Abstract

We have recently observed the strong field dependence of AC-electrowetting of simple electrolyte aqueous drops on parallel gold electrodes, yet the detailed dynamic process of AC-field induced surface wetting remains unclear. In this work, we use fluorescence labeled DNA aqueous solution as a model system to directly visualize the wetting process of aqueous drops under varied AC electric fields by using combined fluorescence microscopy and contact angle goniometer. The electrowetting behavior of DNA aqueous drops is observed at AC-field frequency greater than the reciprocal of the RC time scale for electrode screening. And the onset of AC electrowetting is accompanied by the observed oscillation in drop contour shape and contact line. In addition, the ejection of nanodrops from the parent aqueous drop is observed when the threshold AC-field amplitude is exceeded. A scaling theory based on electrode interfacial screening is developed to quantify the AC-electrowetting behavior with the dependence of AC-field frequency, strength and medium conductivity.

–

Authors

  • Lu Zhang

    Department of Chemical and Biomolecular Engineering, University of Notre Dame

  • Nishant Chetwani

    Department of Chemical and Biomolecular Engineering, University of Notre Dame

  • H.C. Chang

    Department of Chemical and Biomolecular Engineering, University of Notre Dame, University of Notre Dame, Department of Chemical and Biomolecular Engineering, University of Notre Dame

  • Yingxi Elaine Zhu

    Department of Chemical and Biomolecular Engineering, University of Notre Dame, University of Notre Dame, Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA, University of Notre Dame, Department of Chemical and Biomolecular Engineering, Notre Dame, IN 46556