Comprehensive study on electrospray deposition in the single Taylor cone–jet mode by changing the spatial electric potential using a ring-shaped ternary electrode

Yuta Kuwahata,Hiroaki Takehara,Takanori Ichiki

doi:10.1063/1.5142317

Abstract

In this work, the effect of changing the spatial electric potential to the spray current and the threshold voltage in the single Taylor cone–jet mode of the electrospray deposition (ESD) process has been investigated. The spatial electric potential between a nozzle electrode and a counter electrode was deformed by using an additional ring-shaped ternary electrode. The voltage ranges of the stable single Taylor cone–jet were determined from the current–voltage (I–V) characteristics of the system. Depending on the changes occurring in the spatial electric potential around the nozzle electrode, a shift of the threshold voltage to form a stable single Taylor cone–jet was clearly observed. For further investigation, the spatial electric potential and electric-field lines were analyzed by numerical simulations based on the computational finite element method. The deformation of the electric-field lines between the nozzle and counter electrodes implies a lack of droplet adhesion onto the ternary ring electrode and a focus of electrospray. Finally, we demonstrated the ESD of polymer materials with an area of 371 ± 160 mm2 at a deposition rate of 314 ± 73 nm/min. The ESD technique is an important additive surface-modification method that is applicable to a variety of materials and suitable for highly viscous solutions and fragile biological samples.

Highlights

Additive manufacturing technology, which enables the direct introduction of materials on two- and/or three-dimensional structures to create the final products, is a highly attractive and promising manufacturing tool in industry.1 Independent of the specific applications, manufacturing technologies are key to exploiting the potential of materials
The adhesion and accumulation of charged droplets onto the ternary electrode often cause a decline in material’s usage efficiency and a degradation of the controllability of the spatial electric potential by the ternary ring electrode. This adhesion onto the ternary electrode could be avoided by increasing the voltage applied to the ternary ring electrode
A shift in the threshold voltage (Vth-low and Vth-high) to form a single Taylor cone–jet mode with an increase in the voltage applied to the ring electrode (Vring) was observed from the I–V curves

Summary

Introduction

Additive manufacturing technology, which enables the direct introduction of materials on two- and/or three-dimensional structures to create the final products, is a highly attractive and promising manufacturing tool in industry. Independent of the specific applications, manufacturing technologies are key to exploiting the potential of materials. Electrospray deposition (ESD) is a nano/microfabrication technique that can be applied to nanoparticle synthesis, thin-fiber formation, and thin-film deposition. It is an important additive manufacturing technology that can be applied at room temperature and atmospheric pressure.. The advantages of the ESD process are as follows: (i) it enables the generation of monodisperse nanoparticles and uniform thin films; (ii) it is versatile and can be used for a variety of materials, including ceramics, polymers, and biological molecules; (iii) it is simple and easy to operate at atmospheric pressure, and it is scalable for applications in the scitation.org/journal/adv manufacturing industry; and (iv) only a small amount of material is required to deposit a thin layer, and there is minimal material loss in comparison with spin-coating The ESD process has been applied to form polymer films with controlled morphology in applications for organic photovoltaics, organic electronic devices, and the medical coating of implants. The advantages of the ESD process are as follows: (i) it enables the generation of monodisperse nanoparticles and uniform thin films; (ii) it is versatile and can be used for a variety of materials, including ceramics, polymers, and biological molecules; (iii) it is simple and easy to operate at atmospheric pressure, and it is scalable for applications in the scitation.org/journal/adv manufacturing industry; and (iv) only a small amount of material is required to deposit a thin layer, and there is minimal material loss in comparison with spin-coating

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Results

Conclusion