Direct measurement of the viscoelectric effect in water

Di Jin*, Yongyun Hwang, Liraz Chai, Nir Kampf, Jacob Klein*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The viscoelectric effect concerns the increase in viscosity of a polar liquid in an electric field due to its interaction with the dipolar molecules and was first determined for polar organic liquids more than 80 y ago. For the case of water, however, the most common polar liquid, direct measurement of the viscoelectric effect is challenging and has not to date been carried out, despite its importance in a wide range of electrokinetic and flow effects. In consequence, estimates of its magnitude for water vary by more than three orders of magnitude. Here, we measure the viscoelectric effect in water directly using a surface force balance by measuring the dynamic approach of two molecularly smooth surfaces with a controlled, uniform electric field between them across highly purified water. As the water is squeezed out of the gap between the approaching surfaces, viscous damping dominates the approach dynamics; this is modulated by the viscoelectric effect under the uniform transverse electric field across the water, enabling its magnitude to be directly determined as a function of the field. We measured a value for this magnitude, which differs by one and by two orders of magnitude, respectively, from its highest and lowest previously estimated values.

Original languageAmerican English
Article numbere2113690119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
StatePublished - 4 Jan 2022

Bibliographical note

Funding Information:
ACKNOWLEDGMENTS. We thank Alexander Vaskevitch and Sam Safran for valuable comments, Gilad Silbert for providing the numerical solver to the PB equation, Yu Zhang and Ran Tivony for assistance with experiments, and George Degen for assisting us with the camera technique. We also thank the McCutchen Foundation, the Israel Science Foundation-National Natural Science Foundation of China joint program (ISF-NSFC Grant 2577/17), and the Israel Science Foundation (Grant ISF 1229/20) for their support of this work. This project has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement 743016). This work was made possible in part by the historic generosity of the Harold Perlman family.

Publisher Copyright:
© 2022 National Academy of Sciences. All rights reserved.


  • Electrokinetic phenomena
  • Surface forces balance
  • Viscoelectric effect
  • Viscosity/electric field coupling


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