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REVIEW ARTICLE

Mechanisms and modeling of electrohydrodynamic

phenomena

Dajing Gao , Donggang Yao , Steven K. Leist , Yifan Fei , Jack Zhou *
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1 Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, USA
2 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
Abstract: The purpose of this paper is to review the mechanisms of electrohydrodynamic (EHD) phenomenon. From this
review, researchers and students can learn principles and development history of EHD. Significant progress has been identified
in research and development of EHD high-resolution deposition as a direct additive manufacturing method, and more effort
will be driven to this direction soon. An introduction is given about current trend of additive manufacturing and advantages
of EHD inkjet printing. Both theoretical models and experiment approaches about the formation of cone, development of
cone-jet transition and stability of jet are presented. The formation of a stable cone-jet is the key factor for precision EHD
printing which will be discussed. Different scaling laws can be used to predict the diameter of jet and emitted current in
different parametrical ranges. The information available in this review builds a bridge between EHD phenomenon and three-
dimensional high-resolution inkjet printing.

Keywords: Electrohydrodynamic; cone-jet; jet stability; inkjet printing; additive manufacturing

*Correspondence to: Jack Zhou, Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, United States of
America; Zhoug@coe.drexel.edu

Received: October 17, 2018; Accepted: October 17, 2018; Published Online: December 28, 2018
Citation: Gao D, Yao D, Leist SK, Fei Y, Zhou J, 2018, Mechanisms and modeling of electrohydrodynamic phenomena. Int
J Bioprint, 5(1): 166. http://dx/doi.org/10.18063/ijb.v5i1.166

1 Introduction freedom and reduction of assembly time and cost. Inkjet
printing, which is a low cost, high speed and large area
Due to the current trend toward the miniaturization of additive manufacturing process , relies on the generation
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devices, traditional manufacturing methods such as
casting, injection molding, and computer numerical of droplets at or near a nozzle aperture, followed by non-
control machining cannot satisfy the developing needs contact deposition onto a substrate with high spatial
of industries. The lithography-based microfabrication control. Unfortunately, inkjet printing systems share the
experiences inherent limitations in processing diverse same drawback, namely that the droplet size is solely
materials, and extending fabrication into the third dependent on the nozzle diameter, with droplet diameter
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dimension . In addition, it is a time-consuming about twice the nozzle diameter , and the nozzle diameter
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process to use masks and photo-resistant chemicals, cannot be scaled down continuously.
and also expensive when the manufacturing process To overcome the above limitations, electrohydrodynamic
requires a sophisticated, clean room and state-of-the-art (EHD) inkjet printing (also called “EHD jet printing”)
lithographic equipment . Additive manufacturing, based has been proposed as a solution to the limited resolution
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on localized deposition of material and a layer-by-layer of the conventional inkjet printer system, because EHD
printing process, is able to build customized products in printing can generate small droplets without the need
a short time-frame and offers significant advantages over to miniaturize the nozzle. The process involved, called
traditional manufacturing processes in the area of design “electrospray in the cone-jet mode,” uses electrical

Mechanisms and modeling of electrohydrodynamic phenomena © 2019 Gao D, et al. This is an Open Access article distributed under the terms of the
Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial
use, distribution, and reproduction in any medium, provided the original work is properly cited.
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