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REVIEW ARTICLE

Designs and applications of electrohydrodynamic 3D

printing

Dajing Gao, Jack G. Zhou*

Department of Mechanical Engineering and Mechanics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA

Abstract: This paper mainly reviews the designs of electrohydrodynamic (EHD) inkjet printing machine and related
applications. The review introduces the features of EHD printing and its possible research directions. Significant progress has
been identified in research and development of EHD high-resolution printing 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. Designs of EHD printing platform and applications of different technologies are discussed.
Currently, EHD jet printing is in its infancy stage with several inherent problems to be overcome, such as low yielding rate
and limitation of stand-off height. Some potential modifications are proposed to improve printing performance. EHD high-
resolution printing has already been applied to precision components for electronics and biotechnology applications. This
paper gives a review about the latest research regarding EHD used for high-resolution inkjet printing. A starting base is given
to help researchers and students to get a quick overview on the recent development of EHD printing technology.
Keywords: Electrohydrodynamic printing; inkjet printing devices; additive manufacturing

Correspondence to: Jack Zhou, Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, USA; Zhoug@coe.drexel.edu
Received: June 11, 2018; Accepted: November 28, 2018; Published Online: December 26, 2018

Citation: Gao D, Zhou JG, 2019, Designs and applications of electrohydrodynamic three-dimensional printing.
Int J Bioprint, 5(1): 172. http://doi.org/10.18063/ijb.v5i1.172

1. Introduction called “electrospray in the cone-jet mode,” uses electrical
(“Maxwell”) forces to pull the liquids from the nozzle
With the rapid development of modern microelectronic tip, rather than apply thermal or acoustic energy to push
industry and biotechnology, traditional manufacturing liquid from a fine capillary. In the liquid cone, the electric
methods cannot satisfy the developing needs of field causes electric charges to accumulate at the liquid
these industries due to inherent restrictions. Additive surface. The electrical forces counteract surface tension,
manufacturing, based on localized deposition of material and the resultant force leads the meniscus at the nozzle
and a layer-by-layer printing process, is able to build end to change from a hemispherical to a conical shape.
customized products in a short time frame and offers With the increase of electric field, the electric stress at the
significant advantages over traditional manufacturing tip of cone exceeds the surface tension and a droplet or
processes in the area of design freedom and reduction of jet of liquid is emitted toward ground substrate. The EHD
assembly time and cost. Electrohydrodynamic (EHD) inkjet, inkjet printing can be a high-resolution inkjet printing
also called “e-jet,” printing as a mask-less, non-contact, technology because there is a large “neck-down ratio”
direct-write, and additive manufacturing process has between the diameters of the nozzle and the jet: The jet
attracted the remarkable attention. EHD inkjet printing diameter is about two orders of magnitude smaller than
is first proposed as a solution to the limited resolution the nozzle diameter. Thus, in EHD jet printing, the nozzle
of the conventional inkjet printer system since EHD diameter (>100 µm) can be much larger than that used in
printing can produce a thin and intact jet without the thermal or piezoelectric inkjet printing (about 20 µm);
need to miniaturize the nozzle. The process involved, this makes blockages much less likely and makes it easy

Designs and applications of electrohydrodynamic three-dimensional printing © 2019 Gao, 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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