Inkjet-printed Devices Research Articles

МІКРОГІДРОДИНАМІЧНІ ХАРАКТЕРИСТИКИ РОЗПОВСЮДЖЕННЯ ЛАКОФАРБОВОГО ПОКРИТТЯ ВЗДОВЖ ЗАДОВІЛЬНОЇ ПОВЕРХНІ

At present, the methodology of mathematical modeling and computational experiment has become an integral part of the general approaches characteristic of modern information technologies. Its practical implementation significantly increases the efficiency of engineering developments, especially when creating fundamentally new, prototype-free machines and devices, materials and technologies. It allows you to reduce the time and money spent on the use of advanced achievements of physics, chemistry, mechanics and other basic sciences in engineering. In recent years, new trends in hydromechanics related to nanotechnology have been developing [1]. In traditional hydrodynamics, the motion of gases and liquids in macroscopic dimensions is studied. Micro- and nanohydrodynamics is a field of mechanics in which the movement of gas and liquid is studied in sizes that are conditionally related to the field of nanotechnology (less than 100 nm = 0.1 μm). Microhydrodynamics is used in the development of elements of inkjet technology and inkjet printing devices, in describing the movement of microorganisms and large molecules, as well as in various branches of the chemical and transport industry [2]. However, in connection with the use of modern technologies for controlling production processes, more and more accurate studies of related processes are needed. This concerns, first of all, the control of the movement of continuous media in many areas of industry, in transport, everyday life and public utilities. There is a growing interest in the study of flows of various kinds with extraneous inclusions, for example, steam and gas and slag inclusions in the foundry industry, particles in cooling systems in the power industry, particles in the mineral processing industry, particles of chemical compounds in the chemical industry, objects of transportation in hydraulic and pneumatic transport and in many other areas.

Fully inkjet-printed distance-based paper microfluidic devices for colorimetric calcium determination using ion-selective optodes.

Although the determination of calcium ions (Ca2+) is of high importance to monitor water hardness, currently available devices for on-site analysis suffer from a lack of user-friendliness and sensitivity. This work demonstrates fully inkjet-printed and low-cost microfluidic paper-based analytical devices (μPADs) for the simple naked-eye colorimetric determination of calcium ions (Ca2+) in drinking and tap water samples. The quantification of Ca2+ relies on visual readout of the length of a colour-changed detection channel modified with ionophore-doped ion-selective optode nanospheres (nano-optodes), eliminating the requirement of a scanner or a camera. All fabrication steps for deposition of assay reagents have been performed by means of a simple desktop thermal inkjet printer, which is expected to contribute to highly batch-to-batch reproducible device preparation. The detectable Ca2+ concentrations between 0.05 mmol L-1 and 5 mmol L-1 cover the range recommended by the International Organization for Standardization (0.05-2.5 mmol L-1) and the World Health Organization (WHO) guideline for Ca2+ quantification in drinking water (less than 5 mmol L-1). The lowest concentration of Ca2+ detectable by the naked eye was found to be 0.05 mmol L-1, which is below the value achieved with previously reported paper-based devices. μPAD quantified Ca2+ concentrations in tap or drinking waters were within 15% error of the results obtained with a classical complexometric titration. Hence, distance-based μPADs relying on nano-optodes are sensitive and reproducible tools for equipment-free on-site assaying of Ca2+ in real samples.

Variability Modeling for Printed Inorganic Electrolyte-Gated Transistors and Circuits

Electrolyte-gated field-effect transistor technology is an attractive candidate for printed low-power electronics due to its high field-effect mobility and extremely low-voltage operation. Relying on an additive process, inkjet-printed devices display large process variations due to ink-substrate interactions, sensitivity to environmental conditions, such as temperature and humidity, as well as intrinsic variations of the ink. All of these sources of variations may display themselves in non-Gaussian distributions as suggested by our experiments. In this paper, we therefore propose a generic methodology for variability modeling of printed transistors, based on the Gaussian mixture model, which can be used to model any arbitrary distribution of the transistor model parameters. The proposed methodology was tested on two different data sets and has been used to predict the behavior of a measured printed security circuit as well as transistor dc characteristics.

Characterization of electrowetting, contact angle hysteresis, and adhesion on digital microfluidic devices with inkjet-printed electrodes

This investigation characterizes electrowetting performance, contact angle hysteresis, contact line pinning force, and adhesion work on digital microfluidic devices with inkjet-printed electrodes. It also demonstrates electrowetting-induced droplet detachment on these devices. Average performance was similar to cleanroom-fabricated devices in all experimental measurements, but variability was persistently higher on inkjet-printed devices. This appears to be consistent with increased defect density and variation in local electrowetting number caused by increased roughness of printed electrodes. This work suggests that inkjet-printed devices are suitable for the study of colloidal transport and deposition under electric fields and electrowetting-induced droplet detachment when accompanied by rigorous uncertainty analysis.

A General Approach for Fluid Patterning and Application in Fabricating Microdevices

Engineering the fluid interface such as the gas-liquid interface is of great significance for solvent processing applications including functional material assembly, inkjet printing, and high-performance device fabrication. However, precisely controlling the fluid interface remains a great challenge owing to its flexibility and fluidity. Here, a general method to manipulate the fluid interface for fluid patterning using micropillars in the microchannel is reported. The principle of fluid patterning for immiscible fluid pairs including air, water, and oils is proposed. This understanding enables the preparation of programmable multiphase fluid patterns and assembly of multilayer functional materials to fabricate micro-optoelectronic devices. This general strategy of fluid patterning provides a promising platform to study the fundamental processes occurring on the fluid interface, and benefits applications in many subjects, such as microfluidics, microbiology, chemical analysis and detection, material synthesis and assembly, device fabrication, etc.

Modification of polymer gate dielectrics for organic thin-film transistor from inkjet printing

As a prominent printing technique, inkjet printing is an ideal technique for the mass production of solution-processed thin-film transistor. Therefore, in this work, the inkjet-printed organic field effect transistor (OFET) was investigated on different dielectric substrates, especially on polymer-based dielectrics, which have great potential for flexible OFET devices. Comparing with metal oxide dielectrics, polymer dielectric offered a higher surface roughness and worse surface wettability, resulting in reduced charge mobility. Meanwhile, due to the nature of polymer, it had much higher leakage current than metal oxide. Fortunately, with atomic layer deposition of a thin layer of Al2O3, the surface properties of dielectric layer and molecular packing of semiconducting layer were significantly improved, which boosted charge mobility from 0.08 to 0.65 cm2 V−1 s−1 along with significantly reduced leakage current. This method can be broadly applicable to the inkjet-printed OFET devices and flexible OFET devices for further improvement of device performance.

Inkjet Printed Electrodes in Thin Film Transistors

Inkjet printing is a non-vacuum, non-contact, low-cost, and direct patterning thin film deposition technique. Compared to traditional processes, it demands less materials and energy, simplifies processing steps and is compatible with the fast fabrication of flexible and large-size devices, thus potential in the application of thin film transistors. In this paper, we have compared the main techniques of inkjet printing, and discussed the formulation of conductive inks, the deposition of high quality electrodes, and the obtaining of high resolution and high performance thin film transistors. Moreover, the faced problems and corresponding solving methods of inkjet printed thin film transistor with low sintering temperature, small line width, short channel, high mobility, and designed structure are summarized by the understanding of the interaction among inkjet printing devices, materials, processes, and the fabrication of transistors, which providing referential significance of the following research effort.

Inkjet printing of blue phosphorescent light-emitting layer based on bis(3,5-di(9H-carbazol-9-yl))diphenylsilane.

In this study, micropatterning of a blue light emitting, tetraphenylsilane-based phosphorescent material by inkjet printing was investigated. Bis(3,5-di(9H-carbazol-9-yl))diphenylsilane (SimCP2) doped with iridium bis(4,6-difluorophenypyridinato)picolate (FIrpic) was dissolved in a solvent mixture, and various conditions for the solvent composition and drying of films were examined. Homogeneous dot and line patterns with controllable thickness and smooth surface were obtained from a mixture of chlorobenzene and cyclohexanone at a moderate printing speed of 3 mm s−1 and a droplet ejection frequency of 70 Hz. An inkjet-printed device was designed and fabricated in [ITO/PEDOT:PSS /PVK/SimCP2:Flrpic/TSPO1/TPBi/LiF/Al] configuration, from which sky-blue light (0.14, 0.25) was obtained with a luminous efficiency of 10.73 cd A−1 and a power efficiency of 6.13 lm W−1. This amounted to 68% of the performance of an identical device where the emitting layer was spin coated. These results show the potential of inkjet printing as a low-cost patterning method for low molecular weight emitters in blue light emitting devices.

Fabrication of paper-based analytical devices optimized by central composite design.

In this work, an application of a design of experiments approach for the optimization of an isoniazid assay on a single-area inkjet-printed paper-based analytical device (PAD) is described. For this purpose, a central composite design was used for evaluation of the effect of device geometry and amount of assay reagents on the efficiency of the proposed device. The factors of interest were printed length, width, and sampling volume as factors related to device geometry, and amounts of the assay reagents polyvinyl alcohol (PVA), NH4OH, and AgNO3. Deposition of the assay reagents was performed by a thermal inkjet printer. The colorimetric assay mechanism of this device is based on the chemical interaction of isoniazid, ammonium hydroxide, and PVA with silver ions to induce the formation of yellow silver nanoparticles (AgNPs). The in situ-formed AgNPs can be easily detected by the naked eye or with a simple flat-bed scanner. Under optimal conditions, the calibration curve was linear in the isoniazid concentration range 0.03-10 mmol L-1 with a relative standard deviation of 3.4% (n = 5 for determination of 1.0 mmol L-1). Finally, the application of the proposed device for isoniazid determination in pharmaceutical preparations produced satisfactory results.

Photoacid catalyzed organic–inorganic hybrid inks for the manufacturing of inkjet-printed photonic devices

Inkjet printing of photoacid catalyzed organic–inorganic hybrid formulations has been used in the preparation of low-loss optical waveguides.

Inkjet printing of energetic composites with high density.

To explore a new manufacturing method in preparing energetic composites, an inkjet printing device possessing the ability of high precision and flexibility was utilized to deposit six 3,4-dinitrofurazanofuroxan (DNTF) and hexogen (RDX) based explosive inks. The printed quality, inner structure, printed density and crystal morphology of energetic composites were tested, as well as their thermal decomposition properties and detonation properties. The results indicate that inkjet printing provides a good formation uniformity for explosive inks. Interestingly, all energetic composites exhibit excellent printed density with all values higher than 90% theoretical maximum density (TMD). Meanwhile, the composite DNTF/RDX/EC/GAP (54/36/5/5) performs best, reaching 96.88% TMD, which has reached a new height in the three-dimensional printing of energetic composites. Further study manifests that there is no appearance of new material, and the stacking manner of rodlike structures in multilayer manufacturing is the key to achieving such an amazing result. The particles in the energetic composites are spherical with the size ranging from 500 nm to 2 μm and connect with each other closely in the matrix of binders. Moreover, the energetic composites that were directly deposited into wedge channels display a good capability in steadily detonating above the size of 1 × 0.32 mm.

Pyridine-Based Electron-Transport Materials with High Solubility, Excellent Film-Forming Ability, and Wettability for Inkjet-Printed OLEDs.

Film morphology has predominant influence on the performance of multilayered organic light-emitting diodes (OLEDs), whereas there is little reported literature from the angle of the molecular level to investigate the impact on film-forming ability and device performance. In this work, four isomeric cross-linkable electron-transport materials constructed with pyridine, 1,2,4-triazole, and vinylbenzyl ether groups were developed for inkjet-printed OLEDs. Their lowest unoccupied molecular orbital (∼3.20 eV) and highest occupied molecular orbital (∼6.50 eV) levels are similar, which are mainly determined by the 1,2,4-triazole groups. The triplet energies of these compounds can be tuned from 2.51 to 2.82 eV by different coupling modes with the core of pyridine, where the 2,6-pyridine-based compound has the highest value of 2.82 eV. Film formation and solubility of the compounds were investigated. It was found that the 2,6-pyridine-based compound outperformed the 2,4-pyridine, 2,5-pyridine, and 3,5-pyridine-based compounds. The spin-coated blue OLEDs based on the four compounds have achieved over 14.0% external quantum efficiencies (EQEs) at the luminance of 100 cd m-2, and a maximum EQE of 12.1% was obtained for the inkjet-printed device with 2,6-pyridine-based compound.

Influence of the Nozzle Shape on the Breakup Behavior of Continuous Ink Jets

In this work, the influence of nozzle shape on microfluidic ink jet breakup is investigated. First, an industrial ink used in continuous inkjet (CIJ) printing devices is selected. Ink rheological properties are measured to ensure an apparent Newtonian behavior and a constant surface tension. Then, breakup lengths and shapes are observed on a wide range of disturbance amplitude for four different nozzles. Later on, ink breakup behaviors are compared to the linear theory. Finally, these results are discussed using numerical simulations to highlight the influence of the velocity profiles at the nozzle outlet. Using such computations, a simple approach is derived to accurately predict the breakup length for industrial CIJ nozzles.

Low-voltage, high-sensitivity and high-reliability bimodal sensor array with fully inkjet-printed flexible conducting electrode for low power consumption electronic skin

Electronic skin, which has pixels composed of various functional sensors and can be applied to robots and various medical devices by mimicking the human skin, requires flexible, multi-mode, high-sensitivity, and low-interference sensors. In this study, we used a flexible electrode material comprised of organic conductor-elastomer-metal nanoparticles, as the core material and the inkjet printing method as the core process. These were used to form a flexible sensor for electronic skin applications, which involved vertically laminated sensors that utilize different sensing principles, thus enabling the realization of a flexible bimodal sensor with negligible interference. The pressure sensor with low resistivity and a flexible electrode, which was implemented using the sophisticated synthesis method, performed well under low-voltage (0.5mV) operation conditions, exhibited pressure sensitivity over a wide range (3Pa to 5kPa), and showed excellent reliability characteristics (100,000 cycles) that can withstand severe mechanical stress. The temperature sensor, which was formed by a long bent organic conductor-metal line, changes its resistance with temperature, has a resistance change sensitivity of 0.32% per degree of temperature change, and exhibits a hysteresis-free temperature sensing capability. In particular, this device has maintained its robustness even over 5000 bending cycles. The 25 pixels temperature-pressure bimodal sensor array demonstrates very fast response rates, high sensitivity, and negligible interference performance. The low-resistivity/high-flexibility conducting electrode, inkjet printing process, device architecture, and integration scheme proposed in this study are expected to be widely used for electronic skin, multi-mode sensors, and flexible devices.

Inkjet Printed HfO2-Based ReRAMs: First Demonstration and Performance Characterization

In this letter we demonstrate for the first time, the implementation of inkjet-printed high-performance ReRAM devices based on the high-k HfO2 dielectric. Features such as high on/off current ratio and low switching voltages pave the way for low power applications. These characteristics, along with the known flexible properties of the inkjet-printed dielectric layer, make this kind of ReRAMs suitable for portable devices that do not require large integration density i.e. low density nonvolatile memories or reconfigurable analog circuits.

Flexible hybrid circuit fully inkjet-printed: Surface mount devices assembled by silver nanoparticles-based inkjet ink

Nowadays, inkjet-printed devices such as transistors are still unstable in air and have poor performances. Moreover, the present electronics applications require a high degree of reliability and quality of their properties. In order to accomplish these application requirements, hybrid electronics is fulfilled by combining the advantages of the printing technologies with the surface-mount technology. In this work, silver nanoparticle-based inkjet ink (AgNP ink) is used as a novel approach to connect surface-mount devices (SMDs) onto inkjet-printed pads, conducted by inkjet printing technology. Excellent quality AgNP ink-junctions are ensured with high resolution picoliter drop jetting at low temperature (∼150 °C). Electrical, mechanical, and morphological characterizations are carried out to assess the performance of the AgNP ink junction. Moreover, AgNP ink is compared with common benchmark materials (i.e., silver epoxy and solder). Electrical contact resistance characterization shows a similar performance between the AgNP ink and the usual ones. Mechanical characterization shows comparable shear strength for AgNP ink and silver epoxy, and both present higher adhesion than solder. Morphological inspections by field-emission scanning electron microscopy confirm a high quality interface of the silver nanoparticle interconnection. Finally, a flexible hybrid circuit on paper controlled by an Arduino board is manufactured, demonstrating the viability and scalability of the AgNP ink assembling technique.

インクジェット装置による低温度感度複合型 PSP フィルムの開発

インクジェット装置による低温度感度複合型 PSP フィルムの開発

Inkjet-Printed Flexible mm-Wave Van-Atta Reflectarrays: A Solution for Ultralong-Range Dense Multitag and Multisensing Chipless RFID Implementations for IoT Smart Skins

In this effort, the authors implement the first ultralong-range chipless sensing sticker, by providing more than an order of magnitude increase in reading range, compared with the state of the art. The theoretical advantages of the use of millimeter-wave frequencies for high-performance chipless radio-frequency identification (RFID) sensor implementations are first argued before both a new fully inkjet-printed flexible device, based on the Van-Atta reflectarray structure, as well as a new chipless RFID polarimetric interrogation, and time-frequency data-processing approach is then presented and implemented, for operation in the Ka-band. The array, fully inkjet printed on Kapton HN polyimide, was demonstrated as being robust to variations of interrogation angle (between ±70° from normal), as well as to bending. With its demonstrated range, in excess of 30 m, and its proven adequacy for dense multitag and multisensing implementations in indoor environments, the structure may set the foundation for the emergence of flexible printable low-cost sensing smart skins for the Internet of Things.

Rheological characterization of liquid electrolytes for drop-on-demand inkjet printing

Physico-chemical properties of inkjet printing liquids significantly affect the quality of print-out, thus being the key parameter in the performance of printed electronic device (PEDs). Complex hydrodynamic interactions that inks are subjected to in an inkjet printing device has an influence on their rheological response, thus final drop formation, jetting, and drying kinetics. This paper provides a systematic comparison of three PED electrolytes based on different solvents i.e. Sulfolane, 3-Methoxypropionitrile and Acetonitrile that gave them different physico-chemical properties. Rheological properties of printed electrolytes were found to strongly influence the quality of print-outs, which is investigated both optically and morphologically. Best printing results were obtained with the sulfolane-based electrolyte that has the most uniform temperature and shear rate dependent rheological behavior as well as the lowest evaporation rate. By carefully controlling the printing temperature window, it is possible to subject PED electrolytes to higher shearing viscosity profiles while avoiding undesirable dilatant behavior which results in clogged printing nozzles and disrupted droplet trajectory.

Growth-Inhibitory Effect of Chemotherapeutic Drugs Dispensed by Inkjet Bioprinting on Cancer and Non-Cancer Cells

Thermal inkjet technology has long been used in the printing industry, but little has been studied on the benefits that it can provide to the drug-screening field. The objective of the work reported here was a proof of concept of using a modified inkjet printer to have a more accessible and miniature cellomic anticancer drug-screening platform. The authors' previous findings have shown that inkjet-based screening can reliably create isolated arrays of spots of living cells and antibiotics at low volume (180 pl) and high throughput (213 spots/sec) [J. I. Rodríguez-Dévora, B. Zhang, D. Reyna, Z. D. Shi, and T. Xu, “High throughput miniature drug-screening platform using bioprinting technology,” Biofabrication 4, 035001 (2012)]. The methodology of the work reported here included using a modified office inkjet printing device; the authors studied the inhibitory effects of dichloroacetate sodium (DCA) over hepatocellular carcinoma (HepG2) and epithelial cells (EpC). A DCA drug concentration gradient was printed over cell cultures to evaluate the drug's cytotoxic effect. Half maximal and ninety percent inhibitory concentrations (IC50, IC90) were obtained from the dose–response curves and compared with concentrations obtained using the traditional micropipetting technique. The resulting inhibitory concentration values obtained by both dispensing techniques fall within the millimolar range. The significance of these finding is that the proposed screening platform closely mimics the traditional screening outcome at a miniaturized volume rate, thus downsizing the screening process from traditional sub-microliter to nano- or even picoliter range. Inkjet technology shows promise in miniaturizing and expediting the drug-screening process. This platform can be used to asses a preliminary dose–response curve in order to improve the treatment modalities using the patient's limited supply of biopsied cells toward personalized medicine. © 2016 Society for Imaging Science and Technology.