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Title: Dynamics of a nanodroplet under a transmission electron microscope

We investigate the cyclical stick-slip motion of water nanodroplets on a hydrophilic substrate viewed with and stimulated by a transmission electron microscope. Using a continuum long wave theory, we show how the electrostatic stress imposed by non-uniform charge distribution causes a pinned convex drop to deform into a toroidal shape, with the shape characterized by the competition between the electrostatic stress and the surface tension of the drop, as well as the charge density distribution which follows a Poisson equation. A horizontal gradient in the charge density creates a lateral driving force, which when sufficiently large, overcomes the pinning induced by surface heterogeneities in the substrate disjoining pressure, causing the drop to slide on the substrate via a cyclical stick-slip motion. Our model predicts step-like dynamics in drop displacement and surface area jumps, qualitatively consistent with experimental observations.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [3] ;  [3] ;  [5]
  1. A-STAR Institute of High Performance Computing, 1 Fusionopolis Way, Connexis, Singapore 138632 (Singapore)
  2. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore)
  3. (Singapore)
  4. Center for BioImaging Sciences, National University of Singapore, Science Drive 4, Singapore 117543 (Singapore)
  5. School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA and Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)
Publication Date:
OSTI Identifier:
22257752
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Fluids (1994); Journal Volume: 26; Journal Issue: 1; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHARGE DENSITY; CHARGE DISTRIBUTION; POISSON EQUATION; SLIP; SUBSTRATES; SURFACE AREA; SURFACE TENSION; TRANSMISSION ELECTRON MICROSCOPY