Electrohydrodynamic Research Articles

An integrated microfluidic platform for on-demand single droplet dispenser with high accuracy by electrohydrodynamic (EHD) printing technique

Droplet microfluidics has revolutionized single-cell analysis, allowing for ultra-high-throughput sorting of droplets to meet the demands of single-cell sorting. However, accurately and efficiently dispensing target droplets into specific containers for downstream analysis has remained a challenge. Here, we present an integrated microfluidic droplet dispenser based on the electrohydrodynamic (EHD) principle, capable of on-demand single droplet dispensing with high accuracy. Our system uses optical signal activation and EHD actuation to isolate and dispense droplets. The microfluidic droplet auto dispenser consists of four main modules: a pump-drive chip module, an optical automatic signal recognition module, a high voltage control module, and an automated X-Y translation stage module. By optimizing the chip structure and voltage parameter, this platform successfully isolates single Escherichia coli (E. coli) cells onto a Petri dish for downstream cultivation and heterogeneity analysis. In addition, the dispenser microfluidic system dispenses the sorted droplets in a "one droplet, one well" manner, providing an automated method for droplet interface from the micro- to macro- platform. This dispenser system provides a platform for phenotypic screening of single colony pick and single cell analysis

Additive Manufacturing for Terahertz Metamaterials on the Dielectric Surface based on Optimized Electrohydrodynamic Drop-on-demand Printing Technology.

The conventional techniques used to fabricate terahertz metamaterials, such as photolithography and etching, face hindrances in the form of high costs, lengthy processing cycles, and environmental pollution. In contrast, electrohydrodynamic (EHD) drop-on-demand (DOD) printing technology holds promise as an additive manufacturing method capable of producing micrometer- and nanometer-scale patterns rapidly and cost-effectively. However, achieving stable large-area printing proves challenging due to issues related to charge accumulation in insulated substrates and inconsistent meniscus vibration. In this paper, a smooth bipolar waveform driving method is proposed aimed at solving the problems of charge accumulation on insulated substrates and poor print consistency. The method involves utilizing driving waveforms with opposite polarities for neighboring droplets, allowing the charges carried by the printed droplets to neutralize each other. Moreover, extending the duration of the high voltage rise and fall times enhances the consistency of meniscus motion, thereby improving the stability of printing. Through optimization of the printing parameters, droplets with a diameter of 1.37 μm and straight lines with a width of 3 μm were printed. Furthermore, this approach was employed to print terahertz metamaterial surface devices, and the performance of the metamaterial is in good agreement with the simulation results. These findings demonstrate that the method greatly improves the stability of EHD DOD printing, thereby advancing the application of the technology in additive processing at the micro- and nanoscale.

Electroseismic Scholte‐wave analysis: A potential method for estimating shear‐wave velocity structure of shallow‐water seabed sediments

AbstractThe potential application of conducting Scholte‐wave analysis using electroseismic pressure fields excited by an electric current source due to the electrokinetic effect in fluid‐saturated porous seabed sediments is investigated. First, we develop a numerical modelling algorithm by combining the Luco–Apsel–Chen generalized reflection and transmission method with the peak‐trough averaging method to simulate the electroseismic wave fields in stratified fluid/porous media. The modelling results show that the electroseismic pressure signals recorded on the seafloor are mainly composed of evanescent electroseismic waves, and Scholte waves are the dominant wave pattern. Their amplitudes are generally within the order of magnitudes capable of being detected by current seismic instruments. Then, the modified frequency–Bessel transform method is extended to extract the Scholte‐wave dispersion curves from electroseismic pressure fields. Results demonstrate that Scholte‐wave dispersion curves extracted from electroseismic records are superior to those extracted from conventional seismic wave fields excited by an airgun source under the same source–receiver geometry because they contain many overtones and are almost free from the interferences of dispersive guided waves. Furthermore, the Scholte‐wave dispersion inversion results obtained by employing the Levenberg–Marquardt method show that the shear‐wave velocity model inverted by Scholte‐wave dispersion curves extracted from the electroseismic pressure field is more accurate than those obtained by dispersion curves extracted from the seismic wave fields with the guided‐wave removal. The above results indicate that the electroseismic Scholte‐wave analysis method has the potential to evaluate the shear‐wave velocities of shallow‐water seabed sediments.

Interface detection of near-borehole stratified formation under different permeabilities based on seismoelectric logs: A finite-difference modeling

Seismoelectric wavefields arising from electrokinetic effects in fluid-filled porous media are valuable for reservoir exploration. Identifying the formation interface is crucial for reservoir exploration. In this study, we developed a finite-difference (FD) algorithm for calculating borehole seismoelectric wavefields and proposed the use of seismoelectric logs to detect permeability interfaces in near-borehole formations. The borehole-formation acoustic wave and its induced electromagnetic (EM) wavefield are calculated separately using the FD algorithm where the feedback effect of the EM wavefield on the acoustic wave is disregarded. We find that various acoustic-guided waves propagating along the borehole wall (P, S, and Stoneley waves) could generate significant EM waves at the formation interfaces with varying permeabilities. At the horizontal interfaces, the acoustic field does not generate significant interface signals. The EM wave induced by the Stoneley wave is clearly observed in the borehole, whereas those induced by the P and S waves are barely distinguishable. At the tilted interfaces, the Stoneley-wave-induced EM wave is more noticeable, and even P- and S- waves-induced EM waves are clearly observed. The mud cake and invaded zone near the borehole wall have little influence on the interface detection of near-borehole formations using seismoelectric logs. The collar wave during sonic logging while drilling, is a nerve-wracking, noisy signal that can significantly impede the extraction of P- and S-wave velocities. However, the collar wave can generate significant interfacial EM signals, thereby allowing for the detection of formation interfaces using the collar wave. Theoretical calculation shows that compared with the acoustic field in sonic logging, the electric field in seismoelectric logging has more advantages in stratified interface identification. It shows that seismoelectric logging has potential application value in the detection of the formation interface.

Upstream Electrohydrodynamic Conduction Pumping for Flow Distribution Control of Parallel Microchannel Evaporators

Abstract Flow boiling in mini and microchannels has become an attractive option for many applications, such as compact and low charge heat exchangers. Microchannel heat exchangers, however, are more susceptible to maldistribution between parallel flow channels. When operating during uneven heat load conditions, the maldistribution becomes even more severe. Electrohydrodynamic (EHD) conduction pumping technology offers an innovative way to redistribute flow between parallel branches in a microchannel heat exchanger and is also being explored as a next generation mechanism of microgravity heat transport. In EHD conduction pumping, a strong electric field interacts with dissociated electrolytes in dielectric fluid to generate a net body force, and thus, a net flow, with no moving parts, no acoustical noise, lower power consumption, and the ability to operate in microgravity. An EHD conduction pump was designed, fabricated, and tested for upstream flow distribution control of a parallel microchannel evaporator in an opposing configuration. Flow redistribution capability was measured at system flowrates up to 6 ml/min. The EHD conduction pump was capable of completely blocking and reversing the flow in its branch. Recovery from near critical heat flux conditions up to a maximum heat flux of 77.5 W/cm2 was also demonstrated for the operating conditions and design of this study. This was achieved in the absence of enhanced surfaces. The working fluid is HFE 7100. The results show that EHD conduction is able to effectively control the flow distribution of the microchannel evaporator, however, its effectiveness decreases with increasing heat flux and flowrate.

Unipolar Solution Flow in Calcium-Organic Frameworks for Seawater-Evaporation-Induced Electricity Generation.

Seawater-flow- and -evaporation-induced electricity generation holds significant promise in advancing next-generation sustainable energy technologies. This method relies on the electrokinetic effect but faces substantial limitations when operating in a highly ion-concentrated environment, for example, natural seawater. We present herein a novel solution using calcium-based metal-organic frameworks (MOFs, C12H6Ca2O19·2H2O) for seawater-evaporation-induced electricity generation. Remarkably, Ca-MOFs show an open-circuit voltage of 0.4 V and a short-circuit current of 14 μA when immersed in seawater under natural conditions. Our experiments and simulations revealed that sodium (Na) ions selectively transport within sub-nanochannels of these synthetic superhydrophilic MOFs. This selective ion transport engenders a unipolar solution flow, which drives the electricity generation behavior in seawater. This work not only showcases an effective Ca-MOF for electricity generation through seawater flow/evaporation but also contributes significantly to our understanding of water-driven energy harvesting technologies and their potential applications beyond this specific context.

Numerical study on the influence of fluid properties in constant-voltage electrohydrodynamic pulsating jets

The pulsating jet is a common working mode in electrohydrodynamic printing (EHDP), and this process is highly influenced by operating parameters and material properties. In this paper, we investigated the behavior of pulsating jets in liquids with varying physical properties through numerical simulations. We established an electrohydrodynamic (EHD) solver and employed a charge flux restriction step to ensure a realistic distribution of free charges. Our simulations revealed three different ejection regimes: an oscillating cone (OC), a choked jet (CJ), and a stable cone–jet (SJ). We found that the ejection regime is primarily determined by three dimensionless numbers related to liquid properties: the Ohnesorge number, Q0εr/Q, and Q0/(QRe). Based on these dimensionless numbers, we analyzed the influence of liquid properties on pulsating jets in OC and CJ. In OC, the jet's breakage is mainly attributed to the significant oscillation of the Taylor cone, a phenomenon primarily influenced by viscosity and conductivity. In CJ, the emission of the jet is terminated due to the excessive resistant force in the cone–jet transition region. For liquids with low to medium viscosity, the dominant resistant force is either the polarization force or the viscous force depending on whether εrRe is larger or smaller than 1, respectively. In the cases of high viscosity liquids, the viscous force always plays a major role as the primary resistance. These findings provide deeper insight into the physical mechanisms of pulsating jets.

RESPONSE SURFACE METHODOLOGY-BASED NOVEL LATTICE HEAT SINK OPTIMIZATION FOR ELECTROHYDRODYNAMIC (EHD) SPRAY COOLING

In recent years, the size of electronic equipment has become smaller, while the increased processing capacity has led to progressive elevation in the heat flux. As a result of this, the performance of this equipment decreases, and their service lives decrease. Although traditional cooling methods are insufficient to remove the surface heat, new cooling techniques, for example, electrohydrodynamic spray (EHD-spray) cooling, show promise in guaranteeing the operation of these systems under the intended conditions. EHD-spray, also known as electrospray, is an atomization method that provides equal and homogeneous droplets. Although EHD has been used in many studies in the literature, its use in heat transfer has only recently become an important research area. Studies on EHD-spray, which has important advantages such as requiring a very small amount of fluid and low energy, are limited, and there are almost no studies using finned heat sinks. In the study carried out, unique design heat sinks produced by the selective laser melting (SLM) method were optimized with the respond surface method (RSM) Box-Behnken design (BBD) management, that is one of the most effective design methods. In the study where heat sink surface area (HSSA), fluid composition ratio (FCR), and flow rate (FR) were used as variable parameters, the highest heat transfer coefficient (HTC) was found for 100% distilled water at a 17 mL/h flow rate, and the heat sink had the lowest surface area. The results show that EHD-spray is promising for cooling high-heat-flux systems.

Compound giant unilamellar vesicles as a bio-mimetic model for electrohydrodynamics of a nucleate cell.

The understanding obtained by studies on the electrohydrodynamics (EHD) of single giant unilamellar vesicles (sGUVs) has contributed significantly towards a better comprehension of the response of biological cells to electric fields. This has subsequently helped in developing technologies such as cell dielectrophoresis and cell electroporation. For nucleate eukaryotic cells though, a vesicle-in-vesicle compound giant unilamellar vesicle (cGUV) is a more appropriate bio-mimic than a sGUV. In this work, we present an improvised method for the formation of cGUVs, wherein the electrical conductivities of the inner, annular and outer regions of the cGUVs can be modified. A comprehensive experimental study is presented on the EHD of these cGUVs under weak AC fields over a wide range of frequencies, and an encouraging agreement is observed between the experiments and earlier published theoretical studies on concentric cGUVs. The spherical, prolate or oblate spheroidal deformations of a cGUV under AC electric fields depend upon the membrane electromechanical properties as well as the magnitude and direction of the electric traction at the membrane produced by the Maxwell stress that varies with the relative timescales associated with the frequency of the applied AC electric field and that of the membrane charging time and the Maxwell-Wagner relaxation time. This work establishes cGUVs as appropriate bio-mimics for conducting EHD studies relevant to eukaryotic cells.

Fabrication of low-cost and environmental-friendly EHD printable thin film nanocomposite triboelectric nanogenerator using household recyclable materials

Humans generate massive amounts of plastic and electronic waste, which pollute our environment, particularly our water supplies, and cause fatal difficulties. In addition, the increased use of fossil fuels is wreaking havoc on the ecosystem. In order to solve these issues, we describe a simple, low-cost, and environmentally-friendly triboelectric nanogenerator (TENG) made of electronic waste and recycled plastic, and we add nanomaterial to improve power generation using biomechanical energy. The present investigation involves synthesizing carbon dots (CDs) nano-material through a single-step hydrothermal technique and CDs nano-material characterized via UV.Vis Spectroscopy. The proposed carbon dot-graphite nano composite-based TENGs (CGC-TENGs) are created by reusing dry cells (electronic waste) to obtain graphite, plastic bottles to obtain plastic, and synthesized CDs. CGC-TENGs manufactures a simple, low-cost, and environmentally friendly In-house quick and bulk fabrication printed electro hydrodynamics (EHD) electrospray process that uses less solvent and does not require specialist equipment or knowledge. Comparing fabricate TENG device results, in which CDs used produced high voltage (127.31 V)/current (107.12 μA), while not using CDs produced low voltage (95.23 V)/current (104.12 μA) at similar fabrication parameters, the size of the devices are 4.5 cm × 7 cm, and 15 N force applied. The CGC-TENG (δ) has maximum output performance and is thoroughly investigated using an open-circuit voltage of 171.30 V, a short circuit current of 111.39 μA, and a maximum output power density of 53.08 μW/cm2. CGC-TENG (δ) was used to power an electronic glucose monitoring device, and twenty-three blue light-emitting diodes (LEDs) to demonstrate its practical applications. The approach we propose produces renewable energy sources by reutilizing plastic waste and technological waste, providing a practical and sustainable path toward our goal of creating a green planet.

Dynamics and phase behavior of metallo-dielectric rod-shaped microswimmers driven by alternating current electric field.

The ability to move and self-organize in response to external stimuli is a fascinating feature of living active matter. Here, the metallo-dielectric rod-shaped microswimmers are shown to have a similar behavior in the presence of an AC electric field. The silica-copper Janus microrods were fabricated using the physical vapor deposition-based glancing angle deposition technique (GLAD). When the aqueous solution of the microrods was under the influence of an external AC electric field, they were found to exhibit different phases such as clustering, swimming, and vertical standing in response to variation of the applied frequency. The swimming behavior (5-90 kHz) of the rods is attributed to the induced-charge electrophoresis (ICEP) phenomenon, whereas the dynamic clustering (<5 kHz) could be explained in terms of the electrohydrodynamic (EHD) interaction. Interestingly, the rods flip to attain the vertically standing position when responding to the applied electric field above 90 kHz. The reorientation and switching of the major axis of the rod along the field direction is attributed to the electro-orientation phenomenon. This is basically due to the dominance of the electric torque above the upper limit of the characteristic frequency, where the strength of slip flows around the microrods is predicted to be poor. The present study not only offers insight into the fundamental aspects of the dynamics and the phase behavior of rod-shaped microswimmers, but also opens an avenue to design reconfigurable active matter systems with features inspired by biological systems.

FLUID FLOW CONTROL IN POROUS MEDIA WITH CONSIDERATION OF ELECTROKINETIC EFFECTS

The paper presents results of the research on the influence of electrokinetic characteristics of fluids on its flow in porous media. Experimental studies have shown the effect of fluid slippage in the channels of porous media due to the electrically charged boundary "liquid-porous medium". It is shown that the change of flow velocity profile and pressure gradient is caused by the display of electrokinetic effects in the filtration of polar liquids.The investigation has shown that the process of the electrolyte solutions filtration in a porous medium is accompanied by the change in the liquid flow rate and the electro-potential of the flow. The periodic nature of changes in flow characteristics is explained by continuous charge formation and charge interaction in the diffuse layer. Periodic charge accumulation and subsequent charge transfer across the channel cross section depending on the charge sign acquired, as well as compression of the diffuse layer with increasing NaCl electrolyte concentration in aqueous solution may be the cause of fluid flow variations. The observed effects may serve as a tool for controlling fluid flow in water-oil-saturated formations and, in particular, injectivity of injection wells by controlling electrical conductivity of water injected into the formation.

Quality evaluation of house cricket flour processed by electrohydrodynamic drying and pulsed electric fields treatment

House crickets are expected to play a significant role in the future food sector. Electrohydrodynamic (EHD) drying offers an environmentally friendly alternative to conventional drying methods. Pulsed electric fields (PEF) is a non-thermal process that facilitates conventional processes. EHD was applied to house crickets with and without PEF pretreatment, and the effect of PEF and EHD on the quality of the insects was evaluated. PEF pretreatment positively affected the oven drying at 60 °C by reducing its duration and thus decreasing the energy consumption by 14.22%. Moisture removal of EHD was not sufficient to replace oven drying, but when combined with oven drying, the overall energy consumption was reduced by >50%. PEF processing also increased the protein solubility (53.07% higher than the respective control) and antioxidant activity (24.05% higher than the respective control) of the oven-dried samples and reduced the histamine content of the EHD-dried samples (25.87% lower than the respective control).

Influence of Dielectric Material Thickness on the Formation of Atmospheric Plasma

This research examines the effects of dielectric material thickness and geometry on the formation of surface dielectric barrier discharge (DBD) in air. To initiate the discharge process, electrodes are connected to a high voltage source, ionizing the surrounding air and forming a thin layer of plasma near the dielectric material. The electrohydrodynamic (EHD) forces generated during this process are measured and analyzed to determine the influence of dielectric thickness and geometry on plasma formation. This study provides a more comprehensive understanding of the roles that dielectric material properties play in atmospheric plasma generation, contributing to potential optimization in the application of plasma-based technologies.

Harnessing Smectic Ordering for Electric-Field-Driven Guided-Growth of Surface Topography in a Liquid Crystal Polymer.

The guided-growth strategy has been widely explored and proved its efficacy in fabricating surface micro/nanostructures in a variety of systems. However, soft materials like polymers are much less investigated partly due to the lack of strong internal driving mechanisms. Herein, the possibility of utilizing liquid crystal (LC) ordering of smectic liquid crystal polymers (LCPs) to induce guided growth of surface topography during the formation of electrohydrodynamic (EHD) patterns is demonstrated. In a two-stage growth, regular stripes are first found to selectively emerge from the homogeneously aligned region of an initially flat LCP film, and then extend neatly along the normal direction of the boundary line between homogeneous and homeotropic alignments. The stripes can maintain their directions for quite a distance before deviating. Coupled with the advanced tools for controlling LC alignment, intricate surface topographies can be produced in LCP films starting from relatively simple designs. The regularity of grown pattern is determined by the LC ordering of the polymer material, and influenced by conditions of EHD growth. The proposed approach provides new opportunities to employ LCPs in optical and electrical applications.

Study on the effect of positive nematic liquid crystalline physical parameters on EHD properties

ABSTRACT The paper investigated the effects of viscous, elastic and dielectric parameters on the EHD performance of a positive nematic liquid crystal 5CB using CFD (CFD stands for Computational Fluid Dynamics) method. The governing equations including the continuity, momentum and angular momentum equation are presented. The constitutive equations for viscoelastic deformation and shear stress were established based on the L-E and O-F theories. The variables of micro-flow velocity, 5CB molecular director angular velocity, etc were chosen as the EHD (EHD is the abbreviation for electrohydrodynamic dynamics) feature quantities. The application of a DC electric field can cause continuous stable micro-flow in LC cell. The magnitude and direction of micro-flow are coupled with the angular velocity of the 5CB directors and are also influenced by viscoelastic parameters. The relaxation time is inversely proportional to the electric field intensity and dielectric parameters, proportional to the viscous parameters, and independent of the elastic parameters. Using the micro-PIV experiments, the numerical simulation results were tested. A stable approximate antisymmetric ‘S’ type flow profile was obtained in the 5CB cell which is in good agreement with the simulation result. The conclusions can lay a theoretical foundation for further study and application of liquid crystalline microfluidic driving methods.

EHD flow and heat transfer of hybrid nanofluid in a free surface cavity fitted with an internal hot obstacle

The objective of this study is to numerically investigate the effects of electrohydrodynamics (EHD) on coupled free convective thermocapillary flow. The study focuses on a free-surface cavity filled with a hybrid nanofluid (MWCTN- Fe3O4-thermal oil) and containing a hot rigid obstacle. An electric field is applied between the obstacle and the lower cavity wall to induce additional instabilities in this region. This technique aims to eliminate the dead zone typically present in traditional natural convection and is expected to greatly improve heat transfer efficiency. To achieve this objective, the equations governing the EHD phenomenon, as well as the equations defining the physicochemical properties of the hybrid nanofluid, are solved using the finite volume method (FVM) coupled with a blocked-off region procedure. A parametric study is conducted, involving the Marangoni number (surface tension), the thermal Rayleigh number (buoyancy force), the electrical Rayleigh number (electrical force), the nanoparticle concentration, the size and the position of the obstacle. It has been demonstrated that applying of an electric field to the convective-thermocapillary flow of the nanofluid (combining two enhancement techniques) significantly enhances heat transfer, resulting in a more than 230 % increase in the Nusselt number.

3D printing dielectric elastomers for advanced functional structures: A mini‐review

AbstractThree‐dimensional (3D) printed bionic products play an important role in intelligent robotics, microelectronics, and polymers. The printing and manufacturing process of 3D printers is conducive to obtaining soft structures that meet specific requirements, and saves time and cost. Soft intelligent robotics, an emerging research field, has always been developed based on soft materials and actuators with their biological properties. This article reviews the current understanding of 3D bioprinting technologies for dielectric elastomers (DEs), DE actuators (DEAs) and soft robots, such as inkjet, extrusion, laser‐induced and stereolithography bioprinting. 3D printers for fabricating soft materials are presented and classified. The approaches to exploit 3D bioprinters for DEs/DEAs are as follows: (1) 3D printing DEAs utilize ionic hydrogel–elastomer hybrids that are analogous to human muscles, and the DEAs usually have flexible structures and large deformations with multiple functionalities. (2) An electrohydrodynamic (EHD) 3D printer confers high printing resolution and high production efficiency, which offers advantages such as full automation and flexible design. The optimal printing conditions are mainly determined by the effects of printing voltages and ink properties, which are related to the formation of the liquid cone and the printed line width. Furthermore, the advantages of 3D bioprinting technologies have accelerated their development and applications.

Electrohydrodynamic Nanopatterning: A Novel Solvent-Assisted Technique for Unconventional Substrates.

Electrohydrodynamic (EHD)-driven patterning is a pioneering lithographic technique capable of replicating and modifying micro/nanostructures efficiently. However, this process is currently restricted to conventional substrates, as it necessitates a uniform and robust electric field over a large area. Consequently, the use of nontraditional substrates, such as those that are flexible, nonflat, or have high insulation, has been notably limited. In our study, we extend the applicability of EHD-driven patterning by introducing a solvent-assisted capillary peel-and-transfer method that allows the successful removal of diverse EHD-induced structures from their original substrates. Compared with the traditional route, our process boasts a success rate close to 100%. The detached structures can then be efficiently transferred to nonconventional substrates, overcoming the limitations of the traditional EHD process. Our method exhibits significant versatility, as evidenced by successful transfer of structures with engineered wettability and patterned structures composed of metals and metal oxides onto nonconventional substrates.

Energy-saving discharge needle shape for electrohydrodynamic airflow generation

Electrohydrodynamics (EHD) is a way to produce low energy-consuming airflow without moving components. The basis of airflow by EHD is corona discharge. A way to generate corona discharge is done, among others, via needle-type emitter electrodes whose shape and arrangement play a crucial role in the effectiveness of the discharge. Until now, the needle shape was chosen somewhat arbitrarily, although it impacts the energy consumption of the EHD process. We lack systematic studies on the impact of needle shape on the EHD discharge process and associated airflow to help engineers and scientists choose the best shape. This in-silico study screens the impact of the needle shape parameters on EHD performance in terms of electrical power consumption and airflow generation. The study aims to find the ideal EHD needle shape for unrestricted and confined flow. For this purpose, we test three different geometrical configurations. The first configuration is a free-flow single-needle configuration. The second configuration adds a dielectric nearby, which represents a needle enclosure. Lastly, a configuration including a dielectric and a converging nozzle is examined. All studies use a 2D-axisymmetric, fully automatized EHD physics-based model. The first set of parametric studies explores the inherent geometrical properties of the needle shape, like tip radii (10–250 μm), needle cone angle (10–70°), and needle diameters (0.5–2 mm). The second set of parametric studies investigates the operation conditions, such as the emitter-collector distance (10–40 mm), the nozzle contraction ratio (0.04–1), and the operating voltage (6–32 kV). The results of the free-flow configuration show qualitative agreement with experiments on existing needle products. The ideal energy-saving needle shape for free flow configuration features a short conical tip length (i.e., a large angle ≥30°), a diameter of 2 mm, and a needle rip radius of 100 μm. The situation changes when a dielectric is present, and a sharp angle of 10° is favorable to reduce energy consumption. Since a dielectric inverts the optimal needle shape, it makes sense to customize it for a particular application in EHD airflow generation. We provide performance maps that can be used as design charts. This study is a guideline to optimize EHD devices further to reduce energy consumption and increase airflow speed.