On pinchoff behavior of electrified droplets

Min Wook Lee, Na Young Kim, Sam S. Yoon

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


Electrohydrodynamic (EHD) inkjets produce micro- and nano-sized droplets by using an electrostatic field imposed between the nozzle and the substrate. The conducting droplet about to separate (or "pinchoff") from the continuous fluid undergoes a transitional topological change under the competition between the electrical force due the imposed electrostatic field and the forces arising from liquid's own thermo-physical properties, such as viscosity and surface tension. This study is the first attempt to elucidate the pinchoff topology and characteristics of an electrified liquid droplet experimentally. Aspect ratio, which is defined as the ratio of the vertical (b) to horizontal (a) dimensions of a pinchoff droplet, is reported. The range of the dimensionless charging level (Ne) that yields stable microdripping droplets is also reported for various liquids (i.e., acetone, methanol, ethanol, water, dimethylformamide, and methoxyethanol). We experimentally showed that pinchoff topology is a function of both the charge level (Ne) and the electrical conductivity (K) of the droplet liquid. Despite the different properties of the liquids examined, pinchoff topologies were similar when Ne and K were set as constants.

Original languageEnglish
Pages (from-to)114-124
Number of pages11
JournalJournal of Aerosol Science
Publication statusPublished - 2013 Mar

Bibliographical note

Funding Information:
This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP, No. 20104010100640 ), National Research Foundation of Korea (NRF- 2012-0001169 ), and the Converging Research Center Program through the Ministry of Education, Science and Technology ( 2010K000969 ). This work was also supported by the National Research Foundation of Korea (NRF- 2011-0030433 and 2010-0010217 ) grant funded by the Korean government (MEST) and a special grant for the KUCE Crimson Professorship by Korea University.


  • Aspect ratio
  • EHD (electrohydrodynamics)
  • Electrical conductivity
  • Microdripping
  • Pinchoff
  • Topology

ASJC Scopus subject areas

  • Environmental Engineering
  • Pollution
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes
  • Atmospheric Science


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