Multi-Jet Electrospinning With High-Throughput Using a
Coaxial Grooved Nozzle and Two Fluids
Sang Soo Kim,
Aerosol and Particle Technology Laboratory, School of Mechanical, Aerospace & Systems Engineering, Korea
Advanced Institute of Science and Technology, Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea
Technology Convergence R&BD Group, Korea Institute of Industrial Technology, Yuga-myeon, Dalseong-gun,
Daegu 711-880, Republic of Korea
To broaden the applications of the electrospinning tech-
nique, high throughput is one of the primary goals of
many researchers. To overcome the throughput limitation,
we have introduced coaxial grooved nozzles. By using a
coaxial grooved nozzle and two fluids, including polyeth-
ylene oxide (PEO), we are able to achieve stable multi-jet
operation and relatively high throughput. The multi-jets
are initiated by the multi-jet mode of the inner fluid, and
share the total flow rate of the polymer solution. We have
investigated the operating conditions for various flow rate
combinations of two fluids. The morphology of the result-
ing nanofibers is uniform without bead formation. The
fibers have an average diameter of about 350 nm.
ENG. SCI., 58:416–421, 2018.
2017 Society of Plastics Engineers
Electrospinning is a simple and versatile technique for fabri-
cating nanofibers and fibrous mats, capable of producing contin-
uous nanofibers with various types of surface morphology [1–5].
Because of its numerous advantages, the procedure has been
widely employed with variety of polymers in various applica-
tions [1–3, 6, 7]. Although the single-step electrospinning and
electrospray processes have developed rapidly in creating differ-
ent kinds of micro-/nano structures such as core–shell and Janus,
how to manipulate the behaviors of working fluid under electri-
cal fields for high-throughput production is still a big concern
[8–10]. It is not easy to increase the throughput, simply because
the flow rate is one of the most sensitive processing parameters
in electrospinning [11, 12]. Typically, a lower flow rate is more
desirable, so that enough time is allowed for the polymer solu-
tion to evaporate. When the flow rate is high, beaded fibers are
fabricated due to incomplete evaporation of the solvent [13–15].
Various approaches have been tried to overcome the through-
put limitation [16–22]. The most noteworthy of these involve
multi-jet electrospinning, using a multi-nozzle setup. Multi-
needle electrospinning with a linear array of nozzles was inves-
tigated by Bowman et al.  and Theron et al. . Tomas-
zewksi and Szadkowski  improved the nozzle configuration
by examining various types and determining an optimized two-
dimensional configuration. Multi-nozzle approaches guarantee a
relatively high throughput compared to a single-nozzle setup.
However, electrical interference can easily arise between neigh-
boring nozzles, due to their geometrical proximity. The dis-
turbed electric field directly influences not only the
electrospinning operation, but also the characteristics of the
electrospun fibers. To improve the productivity of multi-nozzle
electrospinning, Kim et al. introduced an auxiliary electrode
. Other approaches involve electrospinning without needles.
Yarin and Zussman studied liquid surface electrospinning via a
magnetic field . A porous hollow tube was used by Varab-
has et al. . Wang et al. introduced a conical coil as electro-
spinning spinneret . The advantage of a needle-free
technique is that electrical interference is minimized [24, 25].
Recent studies have shown that mass production of electrospin-
ning is possible using gas jets [26–28].
The primary goal of this research was to find optimized oper-
ating conditions for stable multi-jet formation with high
throughput, using a simple apparatus. The basic concept was
explained in our previous work, which demonstrated the possi-
bility of obtaining high throughput by using a coaxial grooved
nozzle system in the electrospray technique [8, 29]. Coaxial
nozzles are commonly used for fabricating micro encapsulation
or two-layer electrospun fibers [8, 30–32]. However, we intro-
duced coaxial nozzles to provide an effective driving force via
the interaction between two fluids.
MATERIAL AND METHODS
A schematic of the experimental setup is shown in Fig. 1.
The overall system consisted of four parts: a coaxial grooved
nozzle assembly, a liquid feeding system, a high-voltage source,
and fiber collector.
We used two fluids for multi-jet electrospinning. The inner
fluid was ethanol (Merck, Germany), which has good electrical
conductivity, suitable for electrospray, and is easily removed
before it reaches the collector, due to its high volatility. The
outer liquid was polyethylene oxide (PEO), with a molecular
weight of 600,000 g/mol (Sigma-Aldrich, USA). The 6 wt%
PEO was mixed with deionized (DI) water. To make the solu-
tion homogeneous, it was mixed in a vortex generator for about
2 h, and then relaxed for 24 h at room temperature. The physi-
cal properties of the two fluids are listed in Table 1. To prevent
the formation of micro-bubbles, the fluids were sonicated before
being loaded into the syringes. The nozzles and syringe needles
were connected by Teflon tubing, and the prepared fluids were
accurately fed into the nozzles by two syringe pumps (KDS-
100, KD-Scientific, USA).
The flow rate of the outer liquid was set at 6, 8, 10, 12, and
14 mL/h in turn. The flow rate of the inner liquid was varied
according to the number of multi-jets formed at each fixed flow
Correspondence to: W. Kim; e-mail: email@example.com
Contract grant sponsors: National Research Foundation of Korea (NRF)
(funded by the Ministry of Education, Science and Technology, Korea Insti-
tute of Industrial Technology (KITECH) through Research and Development).
Published online in Wiley Online Library (wileyonlinelibrary.com).
2017 Society of Plastics Engineers
POLYMER ENGINEERING AND SCIENCE—2018