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3 pages, 152 KiB

Open AccessEditorial

Special Issue on Printed Electronics 2017

by Je Hoon Oh

Appl. Sci. 2018, 8(7), 1089; https://doi.org/10.3390/app8071089 - 5 Jul 2018

Cited by 1 | Viewed by 1850

Abstract

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(This article belongs to the Special Issue Printed Electronics 2017)

Research

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14 pages, 5818 KiB

Open AccessFeature PaperArticle

A Vector Printing Method for High-Speed Electrohydrodynamic (EHD) Jet Printing Based on Encoder Position Sensors

by Thanh Huy Phung, Luu Ngoc Nguyen and Kye-Si Kwon

Appl. Sci. 2018, 8(3), 351; https://doi.org/10.3390/app8030351 - 28 Feb 2018

Cited by 9 | Viewed by 5182

Abstract

Electrohyrodynamic (EHD) jet printing has been widely used in the field of direct micro-nano patterning applications, due to its high resolution printing capability. So far, vector line printing using a single nozzle has been widely used for most EHD printing applications. However, the [...] Read more.

Electrohyrodynamic (EHD) jet printing has been widely used in the field of direct micro-nano patterning applications, due to its high resolution printing capability. So far, vector line printing using a single nozzle has been widely used for most EHD printing applications. However, the application has been limited to low-speed printing, to avoid non-uniform line width near the end points where line printing starts and ends. At end points of line vector printing, the deposited drop amount is likely to be significantly large compared to the rest of the printed lines, due to unavoidable acceleration and deceleration. In this study, we proposed a method to solve the printing quality problems by producing droplets at an equally spaced distance, irrespective of the printing speed. For this purpose, an encoder processing unit (EPU) was developed, so that the jetting trigger could be generated according to user-defined spacing by using encoder position signals, which are used for the positioning control of the two linear stages. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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15 pages, 3215 KiB

Open AccessArticle

Thermal Characteristics of Plastic Film Tension in Roll-to-Roll Gravure Printed Electronics

by Kui He, Shanhui Liu, Kedian Wang and Xuesong Mei

Appl. Sci. 2018, 8(2), 312; https://doi.org/10.3390/app8020312 - 23 Feb 2018

Cited by 4 | Viewed by 4407

Abstract

In the printing section of a roll-to-roll gravure printed electronics machine, the plastic film tension is directly associated with the product quality. The temperature distribution of the plastic film in the printing section is non-uniform, because of the higher drying temperature and the [...] Read more.

In the printing section of a roll-to-roll gravure printed electronics machine, the plastic film tension is directly associated with the product quality. The temperature distribution of the plastic film in the printing section is non-uniform, because of the higher drying temperature and the lower room temperature. Furthermore, the drying temperature and the room temperature are not constants in industrial production. As the plastic film is sensitive to temperature, the temperature of the plastic film will affects the web tension in the printing section. In this paper, the thermal characteristics of the plastic film tension in roll-to-roll gravure printed electronics are studied in order to help to improve the product quality. First, the tension model including the factor of temperature is derived based on the law of mass conservation. Then, some simulations and experiments are carried out in order to in-depth research the effects of the drying temperature and room temperature based on the relations between system inputs and outputs. The results show that the drying temperature and room temperature have significant influences on the web tension. The research on the thermal characteristics of plastic film tension would benefit the tension control accuracy for further study. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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16 pages, 12269 KiB

Open AccessFeature PaperArticle

Formation and Characterization of Inkjet-Printed Nanosilver Lines on Plasma-Treated Glass Substrates

by Jae-Sung Kwon, Dong Jun Lee and Je Hoon Oh

Appl. Sci. 2018, 8(2), 280; https://doi.org/10.3390/app8020280 - 12 Feb 2018

Cited by 14 | Viewed by 5276

Abstract

In this study, we investigated geometrical characteristics of the inkjet-printed lines with non-zero receding contact angle (CA) on plasma-treated substrates in terms of various printing variables and analyzed the fluidic behavior and hydrodynamic instability involved in the line formation process. The printing variables [...] Read more.

In this study, we investigated geometrical characteristics of the inkjet-printed lines with non-zero receding contact angle (CA) on plasma-treated substrates in terms of various printing variables and analyzed the fluidic behavior and hydrodynamic instability involved in the line formation process. The printing variables included surface energy, droplet overlap ratio, printing frequency, a number of ink droplets, substrate temperature and printing procedures. For the study, a colloidal suspension containing 56 wt % silver nanoparticles in tetradecane solvent was used as a printing ink. It has electrical resistivity of 4.7 μΩ·cm. The substrates were obtained by performing a plasma enhanced chemical vapor deposition (PECVD) process with C₄F₈ and O₂ under various treatment conditions. As results of the experiments, the surface shape and pattern of the inkjet-printed Ag lines were dominantly influenced by the surface energy of the substrates, among the printing variables. Accordingly even when the receding CA was non-zero, bulging instability of the lines occurred forming separate circular patterns or regular bulges connected by ridges. It is a new finding of this study, which is completely different with the bulging instability of inkjet lines with zero receding CA specified by previous researches. The bulging instability decreased by increasing surface temperature of the substrates or employing interlacing procedure instead of continuous procedure for printing. The interlacing procedure also was advantageous to fabricate thick and narrow Ag lines with well-defined shape through overprinting on a hydrophobic substrate. These results will contribute greatly to not only the production of various printed electronics containing high-aspect-ratio structures but also the improvement of working performance of the devices. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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9 pages, 2522 KiB

Open AccessArticle

Nozzle Printed-PEDOT:PSS for Organic Light Emitting Diodes with Various Dilution Rates of Ethanol

by Dai Geon Yoon, MinGyu Kang, Jong Beom Kim and Kyung-Tae Kang

Appl. Sci. 2018, 8(2), 203; https://doi.org/10.3390/app8020203 - 30 Jan 2018

Cited by 19 | Viewed by 4300

Abstract

In this study, we investigated the ink formulation of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the hole injection layer (HIL) in an organic light emitting diode (OLED) structure. Generally, in a PEDOT:PSS solution, water is incorporated in the solution for the solution process. However, [...] Read more.

In this study, we investigated the ink formulation of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the hole injection layer (HIL) in an organic light emitting diode (OLED) structure. Generally, in a PEDOT:PSS solution, water is incorporated in the solution for the solution process. However, the fabrication of thin film which contained the water, main solvent, could not easily form by using printing technology except spin-coating process because of the high surface tension of water. On the other hand, mixing PEDOT:PSS solution and ethanol (EtOH), a dilution solvent, could restrain the non-uniform layer that forms by the high surface tension and low volatility of water. Therefore, we printed a PEDOT:PSS solution with various concentrations of EtOH by using a nozzle printer and obtained a uniform pattern. The line width of PEDOT:PSS diluted with 90% (volume ratio) ehtanol was measured as about 4 mm with good uniformity with a 0.1 mm nozzle. Also, imaging software and a scanning electron microscope (SEM) were used to measure the uniformity of PEDOT:PSS coated on a substrate. Finally, we fabricated a green phosphorescent OLED device with printed-PEDOT:PSS with specific concentrations of EtOH and we achieved a current efficiency of 27 cd/A with uniform quality of luminance in the case of device containing 90% EtOH. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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9 pages, 2139 KiB

Open AccessFeature PaperArticle

Effect of Substrates on the Dynamic Properties of Inkjet-Printed Ag Thin Films

by Deokman Kim, Yunsang Kwak and Junhong Park

Appl. Sci. 2018, 8(2), 195; https://doi.org/10.3390/app8020195 - 29 Jan 2018

Cited by 2 | Viewed by 3498

Abstract

The dynamic properties of inkjet-printed Ag thin films on flexible substrates were measured using flexural wave propagation. The Ag nanoparticle suspension was inkjet-printed on polyimide (PI), silicon wafer, and glass. The effects of flexible substrates on the dynamic properties of the films were [...] Read more.

The dynamic properties of inkjet-printed Ag thin films on flexible substrates were measured using flexural wave propagation. The Ag nanoparticle suspension was inkjet-printed on polyimide (PI), silicon wafer, and glass. The effects of flexible substrates on the dynamic properties of the films were investigated. Beam-shaped Ag-printed substrates were fabricated by pico-second laser pulse cutting. The wave approach was presented to analyze the vibrations of the thin film on the substrates. The Young’s modulus and loss factor of the Ag thin films with the substrates were represented by the combined bending stiffness of the bilayer beam. The vibration response of the base-excited cantilever was measured using an accelerometer and laser Doppler vibrometer (LDV). Vibration transfers were analyzed to obtain dynamic characteristics of the Ag-printed bilayer beam. The substrate affects the reduction of the Ag thin film thickness during the sintering process and surface roughness of the film. The proposed method based on the wave approach allows measurement of the dynamic properties regardless of the ratio of the modulus between the thin film and substrate. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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8 pages, 1468 KiB

Open AccessArticle

Effect of Meniscus Damping Ratio on Drop-on-Demand Electrohydrodynamic Jetting

by Samuel Haedong Kim, Heuiseok Kang, Kyungtae Kang, Sang Ho Lee, Kwan Hyun Cho and Jun Young Hwang

Appl. Sci. 2018, 8(2), 164; https://doi.org/10.3390/app8020164 - 24 Jan 2018

Cited by 14 | Viewed by 3438

Abstract

Drop-on-demand (DOD) electrohydrodynamic (EHD) jet printing uses a nozzle and pulsated electric fields to eject small ink droplets of functional material to the appointed spot of a substrate at the appointed time, which offers solutions of high resolution patterning for fabrication of printed [...] Read more.

Drop-on-demand (DOD) electrohydrodynamic (EHD) jet printing uses a nozzle and pulsated electric fields to eject small ink droplets of functional material to the appointed spot of a substrate at the appointed time, which offers solutions of high resolution patterning for fabrication of printed electronics, bioengineering, and display. Because the EHD jet connects fine drops to yield a fine pattern, it is essential to realize high throughput by generating drops quickly and reliably. In this study, the characteristics of jetting frequency were experimentally investigated as a function of nozzle dimensions by measuring response of jetting frequency to pulsating frequency which is varying from 1 Hz to 2000 Hz. The results showed that, even when the nozzle diameter is the same, the other dimensions of the nozzle significantly change the response of jetting to high pulsating frequency. Using a linear damping model describing hydrodynamic motion of ink inside the nozzle, the different behavior of the jetting frequency was explained via the different damping ratio of the oscillating ink: contrary to an underdamped system, an overdamped system supports a jetting frequency higher than the natural frequency. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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13 pages, 2736 KiB

Open AccessArticle

The Effect of Laser Pulse Widths on Laser—Ag Nanoparticle Interaction: Femto- to Nanosecond Lasers

by Jin-Woo Jeon, Sangwoo Yoon, Hae Woon Choi, Joohan Kim, Dave Farson and Sung-Hak Cho

Appl. Sci. 2018, 8(1), 112; https://doi.org/10.3390/app8010112 - 14 Jan 2018

Cited by 55 | Viewed by 8124

Abstract

The effect of the laser pulse width on the production of nanoparticles by laser fragmentation was investigated. Laser pulse widths of 164 fs, 5 ps, 4 ns, 36 ns, 64 ns, and 100 ns were used. To assess the effect of the laser [...] Read more.

The effect of the laser pulse width on the production of nanoparticles by laser fragmentation was investigated. Laser pulse widths of 164 fs, 5 ps, 4 ns, 36 ns, 64 ns, and 100 ns were used. To assess the effect of the laser pulse width on the energy distribution in the nanoparticles, the energy distribution was simulated using wave optics. Silver (Ag) nanoparticles were produced by laser irradiation of an Ag target in distilled water. The wavelength of the femtosecond, picosecond, and nanosecond lasers used was 1070 nm, and their fluences were 0.10–0.13 mJ/cm². Nanoparticle microstructure was visualized by transmission electron microscopy and scanning electron microscopy, and the nanoparticle size distribution was evaluated using a particle size analyzer. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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7988 KiB

Open AccessArticle

A Compact and Multi-Stack Electromagnetic Bandgap Structure for Gigahertz Noise Suppression in Multilayer Printed Circuit Boards

by Myunghoi Kim and Seungyoung Ahn

Appl. Sci. 2017, 7(8), 804; https://doi.org/10.3390/app7080804 - 7 Aug 2017

Cited by 7 | Viewed by 3983

Abstract

In modern printed electronics, the performances of a circuit and a device are severely deteriorated by the electromagnetic noise in the gigahertz (GHz) frequency range, such as the simultaneous switching noise and ground bounce noise. A compact and multi-stack electromagnetic bandgap (CMS-EBG) structure [...] Read more.

In modern printed electronics, the performances of a circuit and a device are severely deteriorated by the electromagnetic noise in the gigahertz (GHz) frequency range, such as the simultaneous switching noise and ground bounce noise. A compact and multi-stack electromagnetic bandgap (CMS-EBG) structure is proposed to suppress the electromagnetic noise over the GHz frequency range with a short distance between a noise source and a victim on multilayer printed circuit boards (MPCBs). The original configuration of the stepped impedance resonators is presented to efficiently form multiple stacks of EBG cells. The noise suppression characteristics of the CMS-EBG structure are rigorously examined using Floquet-Bloch analysis. In the analysis, dispersion diagrams are extracted from an equivalent circuit model and a full-wave simulation model. It is experimentally verified that the CMS-EBG structure suppresses the resonant modes over the wideband frequency range with a short source-to-victim distance; thus, this structure substantially mitigates GHz electromagnetic noise in compact MPCBs. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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7898 KiB

Open AccessArticle

Measurements of Thermally-Induced Curvatures and Warpages of Printed Circuit Board during a Solder Reflow Process Using Strain Gauges

by Meng-Chieh Liao, Pu-Shan Huang, Yi-Hsien Lin, Ming-Yi Tsai, Chen-Yu Huang and Te-Chin Huang

Appl. Sci. 2017, 7(7), 739; https://doi.org/10.3390/app7070739 - 20 Jul 2017

Cited by 20 | Viewed by 9845

Abstract

Measurements of the curvatures and warpages of a printed circuit board (PCB) during a thermal solder reflow process using strain gauges are proposed in this study. In the experiments, a shadow moiré is used for measuring the out-of-plane deformations (or warpage) of a [...] Read more.

Measurements of the curvatures and warpages of a printed circuit board (PCB) during a thermal solder reflow process using strain gauges are proposed in this study. In the experiments, a shadow moiré is used for measuring the out-of-plane deformations (or warpage) of a bi-material plate and a PCB with dual in-line memory module (DIMM) sockets during solder reflow heating, while the finite element method (FEM) is used to analyze the thermally-induced deformation of the PCB specimen for ensuring the validity of the measurement. Conventional strain gauges are employed to measure the strains (albeit as in-plane strain data) in both specimens during the solder reflow process. The results indicate that the strain gauge-measured strain data from the top and bottom surfaces of both specimens during the solder reflow can be converted into curvature data with specific equations, and even into global out-of-plane deformations or warpages with a proposed simple beam model. Such results are also consistent with those from the shadow moiré and FEM. Therefore, it has been proved that the strain gauge measurement associated with the simple beam model can provide a method for the real-time monitoring of PCB deformations or warpages with different temperatures during the solder reflow process. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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16 pages, 2249 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Inkjet-Printed and Paper-Based Electrochemical Sensors

by Ryan P. Tortorich, Hamed Shamkhalichenar and Jin-Woo Choi

Appl. Sci. 2018, 8(2), 288; https://doi.org/10.3390/app8020288 - 14 Feb 2018

Cited by 99 | Viewed by 12404

Abstract

It is becoming increasingly more important to provide a low-cost point-of-care diagnostic device with the ability to detect and monitor various biological and chemical compounds. Traditional laboratories can be time-consuming and very costly. Through the combination of well-established materials and fabrication methods, it [...] Read more.

It is becoming increasingly more important to provide a low-cost point-of-care diagnostic device with the ability to detect and monitor various biological and chemical compounds. Traditional laboratories can be time-consuming and very costly. Through the combination of well-established materials and fabrication methods, it is possible to produce devices that meet the needs of many patients, healthcare and medical professionals, and environmental specialists. Existing research has demonstrated that inkjet-printed and paper-based electrochemical sensors are suitable for this application due to advantages provided by the carefully selected materials and fabrication method. Inkjet printing provides a low cost fabrication method with incredible control over the material deposition process, while paper-based substrates enable pump-free microfluidic devices due to their natural wicking ability. Furthermore, electrochemical sensing is incredibly selective and provides accurate and repeatable quantitative results without expensive measurement equipment. By merging each of these favorable techniques and materials and continuing to innovate, the production of low-cost point-of-care sensors is certainly within reach. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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