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In the domain of 3D food printing, previously developed 3D candy printers focused majorly on soft candy materials, such as chocolate, gum, and jelly. These techniques also presented limitations in terms of reproducibility and model diversity. Accordingly, this study aimed to address these problems via investigation of the behavior of sugar, a printing material, with respect to the extrusion process of 3D hard candy manufacture and analysis of the reproducibility. Moreover, the relationship among the nozzle movement speed, extrusion speed, and pattern spacing was analyzed to derive the optimal conditions for the extrusion process for reproducing a 3D virtual model. It was observed that the pattern spacing was optimized at 0.9 mm, considering a stable manufacturing process and manufacturing speed. The optimized parameter values of nozzle diameter, nozzle-substrate distance, pneumatic pressure, control temperature, printing speed, and standoff distance were computed through a correlation analysis conducted with pattern spacing. Under these conditions, moldings with a total height of 6 cm could be built. Moreover, a considerably high reproducibility of the 3D model was achieved on consideration of changes in the pattern thickness according to the nozzle movement speed and extrusion speed. Overall, this study contributes to literature and bridges a gap therein by presenting a process technology for guaranteeing the reproducibility of 3D models. It also demonstrates that the production of personalized custom shapes will be effective and feasible in the future.

The inherent tradeoff between the optical mode confinement and the propagation loss due to the high dissipation level of metals has proved to be a significant setback in the design of plasmonic waveguide-based devices. In this Letter, we demonstrate a ring-less nanogap resonator consisting of two straight waveguides with metallic layers and a nanogap between. A finite-difference time-domain simulation of the proposed structure reveals that it exhibits a band-stop and lasing characteristics. The obtained full-width at half-maximum, free spectral range, and Q-factor values are found to be improved as compared to those obtained without a nanogap. Thus, to the best of our knowledge, the new resonator and laser structure can be obtained through the waveguide structure without the ring-shaped resonator.

Non-contact printing methods have recently attracted attention in the field of optoelectronics manufacturing including solar cells, light-emitting diodes, photodetectors, and transparent electrodes. Non-contact printing is a powerful and cost-effective technique for high-precision processing through the direct printing of optoelectronic devices. Multimode optical waveguides which are generally fabricated by lithography or reactive ion etching reported exhibiting minimum losses of 0.02 dB/cm and 0.2 dB/cm, respectively. Although these techniques are well established in the fabrication process, it is complicated and possible only with large-scale equipment. Non-contact printing technique can be used to solve these problems. In this paper, we design and demonstrate the printing of optical waveguides with a flexible substrate. The waveguide width was advanced through the nozzle design within 500 μm and applied to the high voltage and nozzle structure so that the capillary force does not damage the pattern.

Printed organic sensors are of significant importance owing to their simplicity, low cost, easy fabrication and solution processability. However, organic sensors often face the problem of performance degradation when exposed to ambient environment therefore, the effect of humidity needs to be studied for prolonging the lifetime of organic sensors. In this study, we propose atomically thin and highly reliable encapsulation layer on the surface of an organic functional material to enhance its lifetime as a temperature sensing unit. Our organic temperature sensor is based on a conductive and uniform IDT pattern deposited on a glass substrate through advanced printing technology of reverse offset. Thin film of PEDOT:PSS is used as the temperature sensitive functional layer deposited through electrohydrodynamic atomization while the organic thin film was encapsulated with aluminum oxide (Al2O3) through spatial atmospheric atomic layer deposition system (SAALD). The temperature range of the developed sensors was from 25 to 90 °C with relative humidity reaching up to 75% RH. The obtained results exhibited that Al2O3 encapsulation deposited through SAALD significantly enhanced the linearity, repeatability, endurance (50 cycles), retention (1 month) and lifetime of organic temperature sensor as compared to the non-encapsulated sensor. The performance degradation mechanism of non-encapsulated sensor due to humid environment has been discussed in detail. This study contributes an important step forward for preserving the performance and elongating the lifetime of organic electronic devices through a single atomically thin encapsulation.

Photonic integrated circuits (PICs) have been a very active research area ever since the inception of integrated optics for the application of the wavelength division multiplexing networks. In this paper, we reported the T-shaped nano-gap resonator with the straight waveguide without the ring shape resonator, which is replaced with a straight waveguide, nano-metallic layer, T-shaped waveguide, and nano-gap. We investigated the resonant properties of the structure using the FDTD method. The results reveal that the proposed structure has the band-stop characteristic for PICs.

Several research works for finding and optimizing the methods of dispensing high viscosity phosphor used in the fabrication ofR white LED’s are currently in progress. High viscosity phosphor dispensing with a high accuracy is crucial because the dispensing rate and uniformity directly affect parameters such as the CIE chromaticity diagram, color temperature and luminous flux of white LED’s. This study presents a novel method of dispensing high viscosity phosphor using electrohydrodynamic printing. The dispensing rate was optimized less than 0.01 mg phosphor using experiments and optimizing the process parameters including the standoff distance from the nozzle to the substrate, ink supply pressure, and multi-step pulsed waveform magnitude ratio. The dispensing rate was measured by dispensing 20 dots using drop-on-demand with the optimized parameters, and the experiments were repeated 10 times to maximize the data accuracy. The average dispensing rate that can be reliably used for high viscosity phosphor dispensing was 0.0052 mg.ecivd 28 D mbr 015Revised 30 March 2016Accepted 6 Arpil 2016

Currently various studies are underway for dispensing high-viscosity phosphor. These studies have reported limita- tions and challenges in the dispensing process. The discharged amount of phosphor was approximately the same each time which is important for the implementation of high-efficiency white LED technology. This paper present high-viscosity phosphor dis- pensing process for white LED implementation by using electrostatic printing technology. The voltage controlled DOD (Drop- On-Demand) discharge experiment was studied to determine angle of drop meniscus at nozzle and dot diameter. With increase in Discharge voltage, the discharge angle of meniscus increased while dot diameter decreased. Therefore it can be concluded that we can control the discharge rate by controling the discharge angle of meniscus.

The study demonstrates the electrostatic atomization behavior of polymer based solution and the fabrication of the thin film of poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylenevinylene] polymer using electrospray deposition technology. In this study, the polymer ink was developed and was subjected to electrostatic atomization. The ink behavior under the influence of electric field was investigated and the operating envelope of the ink was explored. The film deposited through electrospray was then characterized in physical as well as electrical aspect. Finally, the organic diode with electrosprayed polymer was fabricated. The performance of the diode device was investigated by current–voltage measurement and compared with a spin-coated device.

A novel route to thin-film fabrication of graphene oxide (GO) is presented using a well-known technique, i.e., electrospray deposition. For deposition of the graphene-oxide thin film, grapheneoxide ink containing 0.025 wt% graphene oxide flowing through a metal capillary was subjected to a static electric field in order to generate atomized droplets, thereby depositing a uniform thin film of graphene oxide on an indium-tin-oxide coated polyethylene terephthalate substrate. The quality of the layer was characterized by analyzing the surface morphology and the thickness, and the electrical measurements on the single film were performed. In order to study the resistive switching behavior of GO, a prototype GO-based resistive switching device having an active area of 0.026 mm2 was developed and was analyzed by current voltage measurements. The IV characteristics of the device successfully showed a typical non-volatile resistive switching behavior for a GO layer having the retention times of ∼103 s, thus highlighting the electrospray deposition technology as a reliable candidate for the fabrication of GO layers.

The Electrostatic Inkjet system has many applications in cost and time effective manufacturing of printed electronics like RFIDs, OLEDs and flexible displays etc. This paper presents pneumatic ink supply system for an electrohydrodynamic deposition (EHD) setup for the precise pressure control to produce a small amount of discharge at the end of the capillary. The meniscus shape depends upon the applied pneumatic pressure to the ink supply system. Furthermore, this paper also compares meniscus shapes at different applied pneumatic pressures. It is concluded that patterning of constant line-width can be achieved better by controlling the meniscus shape using this technique.

This paper represents the multiphysics simulation of droplet generation of ink containing conductive nano-particles through electrostatic forces on substrate. The main focus is to investigate the phenomena by generating the drops through a nozzle with the help of electrostatic forces. The electrostatic based deposition system has vast application in printed electronics and biotechnology. In electrostatic deposition mechanism for droplet generation, a strong electric potential is applied at the tip of the nozzle; due this electric potential, the liquid containing the nano-particles experience strong electrostatic static forces at the interface with the air (at the tip of the nozzle). When these electrostatic forces exceed the internal (viscous forces) and external forces (surface tension), a deformation takes place which results in the flow of the liquid in the form of droplets. The size of the droplet is dependent on different parameters like applied voltage, properties of the ink, dimension of the nozzle. To have better understanding of this, a numerical simulation was performed based on multi-physics approach. Multiple simulations were performed by changing the position of electrode in nozzle and varying the applied voltage. Droplet size with respect to applied voltage was evaluated; electric field with respect to applied voltage and time for the droplet generation was also evaluated through these simulations. This study will help in better understanding the parameters of droplet generation phenomena and optimal design of the nozzle for the electrostatic inkjet system.

There has been growing interests in direct patterning of metallic contents on the surface of the substrate without including complex steps of the microfabrication lithography process. The direct fabrication process using electrostatic ink-jet printing can be expected to be a powerful tool for both nanotechnology research and applications such as microelectronics. The droplet ejection voltage, meniscus, cone-jet behavior, and counter electrode distance depends on the ink properties such as surface tension, viscosity, and percentage of metallic pigments. In this paper, 2-μm level needle-type electrostatic head designs for contact-less fabrication of printed electronics, composed of differently treated surface materials, have been studied and analyzed. The electrostatically actuated ink-jet heads were tested and compared for low power and high resolution on ink containing metallic nano-particle particles as pigments. The two laboratory-fabricated discrete and electrostatically actuated ink-jet heads, one made by poly di-methyl siloxane modeling process and other through micro-electrical discharge machine techniques, were compared, and their orifice outlet surface (hydrophobic and hydrophilic) condition influence has been discussed. The paper also investigates different dripping behaviors of metallic ink under the influence of counter electrode distance, voltages, and materials. The observation of droplet ejection with high-speed camera revealed that in the case of hydrophobic head, better meniscus shape and ejection was achieved even at low voltage compared to the hydrophilic head. It was also found that the less flow rate is required in hydrophobic head. Printing characteristic of the hydrophilic nozzle head was also compared with the hydrophobic head on PET substrate.

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO) and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PEDOT:PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films’ characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics.

In the hybrid SAW-ED deposition system for conductive thin-layer, droplets generation depend upon the SAW. Also, the electrostatic field can help pull off the droplets to the substrates. In this paper, the efficiency of hybrid SAW-ED head is studied analytically. For the development of hybrid SAW-ED deposition system, the optimized parameters for conductive thin-layer can be ascertained from the results discussed here. The background of this research is to get micro droplets and successive spray and the optimal conditions for the development of conductive thin-layer needed for devices of printed electronics through hybrid SAW-ED deposition system.

There have been growing interests in direct patterning of metallic contents on the surface of the substrate without including complex steps of the micro fabrication lithography process. The direct fabrication process using ink-jet printing can be expected to be a powerful tool for both nanotechnology research and applications such as micro electronics. The electrostatic inkjet system has a huge number of applications in terms of cost and time effected manufacturing of printed electronics like RFID, electronic devices and flexible display, solar cell, sensors etc. Inkjet printers operate by propelling various size droplets of conductive ink onto the non conductive substrate. For experimental purpose, an integrated electrostatic inkjet nozzle head was fabricated. For the charging of ink meniscus, an electrode is inserted inside the nozzle head containing conductive ink. The difference between the charge meniscus and ground electrode is depended on the ink properties like surface tension, viscosity and number of metallic pigments. Therefore, for the extraction of droplets, a ring type ground terminal with internal diameter of 1.5mm, 1mm. 0.5mm with a fixed distance of 500um from the meniscus is employed. The paper is focused on the different meniscus shape and extractions in meniscus before dripping is evaluated through experiments. And optimal ground is proposed. This study will help to develop and analysis the integrated electrostatic nozzle head and aspects of the nozzle head.