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Innovative fluorescence security technologies for paper-based information are still highly pursued nowadays because data leakage and indelibility have become serious economic and social problems. Herein, we report a novel transient bio-fluorochromic supramolecular co-assembly mediated by a hydrolytic enzyme (ALP: alkaline phosphatase) towards rewritable security printing. A co-assembly based on the designed tetrabranched cationic diethynylanthracene monomer tends to be formed by adding adenosine triphosphate (ATP) as the biofuel. The resulting co-assembly possesses a time-encoded bio-fluorochromic feature, upon successively hydrolyzing ATP with ALP and re-adding new batches of ATP. On this basis, the dynamic fluorescent properties of this time-encoded co-assembly system have been successfully enabled in rewritable security patterns via an inkjet printing technique, providing fascinating potential for fluorescence security materials with a biomimetic mode., Rewritable security printing has been successfully achieved based on a biofuel-driven transient supramolecular co-assembly mediated by an enzyme, providing fascinating potential for artificial functional materials with a biomimetic mode.

Electrohydrodynamic (EHD) inkjet printing is a type of potential non-contact micro/nanoscale manufacturing technology. The printed droplet dimension plays an important role in EHD inkjet printing due to its significant influence on printing quality and the resolution of patterns. The complexity of the mechanism and the limited process optimization techniques present a challenge in obtaining the desired printing resolution, eventually becoming an expensive and time consuming endeavor. Recent developments in computational fluid dynamics (CFD) bring an effective alternative to alleviate the aforementioned challenges. In this study, a CFD model is proposed to investigate the mechanism of the cone-jet printing process in EHD inkjet printing. The complete cone-jet printing process is successfully simulated with four phases: Taylor cone formation, cone-jet generation, jet break and droplet expansion. A further analysis predicts the jetting diameter and printed droplet diameter with different operating parameters and substrates. The simulation has a satisfactory agreement with experiments in predicting the printing behavior and printing quality (jetting diameter, printed droplet diameter). Such advancement in modeling can be utilized to guide the quick determination of operation parameters for the desired printing resolution when given a new ink.

Inkjet printing is a very attractive technology for printed electronics and a potential alternative to current high cost and multi-chemical lithography processes, for display and other applications in the electronics field. Inkjet technology can be employed to fabricate organic light emitting diodes (OLED), quantum dots displays, and thin-film transistors (TFTs). Among potential applications, metal oxide TFTs, which have good properties and moderate processing methods, could be prepared using inkjet printing in the display industry. One effective method of improving their electrical properties is via doping. Lithium doping an oxide TFT is a very delicate process, and difficult to get good results. In this study, lithium was added to indium-zinc oxide (IZO) for inkjet printing to make oxide TFTs. Electrical properties, transfer and output curves, were achieved using inkjet printing even at the relatively low annealing temperature of 200 oC. After optimizing the inkjet process parameters, a 0.01 M Li-doped IZO TFT at 400 oC showed a mobility of 9.08 ± 0.7 cm2/V s, a sub-threshold slope of 0.62 V/dec, a threshold voltage of 2.66 V, and an on-to-off current ratio of 2.83 × 108. Improved bias stability and hysteresis behavior of the inkjet-printed IZO TFT were also achieved by lithium doping.

3D printing or additive manufacturing is an emerging technique for the fabrications of biomedical components. Several researchers are working on fabrications of the biomedical components, future prospective of implantation, and transplantation aspects. The current review presents a meticulous summary of research work done so far by the researchers in the view of design and fabrications about biomedical components by using 3D printing technology such as fused deposition modeling (FDM), inkjet printing, stereolithography, and selective laser sintering (SLS). The design and fabrications of biomedical components include 3D printing of bone, low-cost high-quality prosthetics, intervertebral disks, medical equipment, heart valve, building tissues using blood vessels and drugs. The objective of this review article is to explore different additive manufacturing processes, challenges, and future developments for 3D printing for biomedical components.

A series of triphenylamine (TPA) derivatives with various substituent groups were prepared and showed different absorption and fluorescence characteristics due to the substituent effect. On account of the existence of pyridine units, these TPA derivatives exhibited acid-induced tunable multicolor fluorescence emission including white light emission. In addition, acid-induced fluorescence regulation of these compounds has been also realized in the solid state, which enable them to be successfully constructed the stimuli-responsive fluorescent films and fluorescent inks for inkjet printing.

In this paper, the effects of the combination of solvents on the uniformity of a dried emitting layer and on device performance were studied. Green emitter inks with various solvents were prepared, and it was seen that good film uniformity of printed layers could be obtained with a solvent mixture with different boiling points, which reduced the coffee ring effect on a dried surface. During the inkjet process, the drop injection condition aiming was also controlled for better drop-to-drop spacing and reduction of the line-edge roughness. Printed patterns of a small molecular/polymer hybrid emitting layer, composed of the chlorobenzene-dichlorobenzene solvent mixture, showed significantly reduced roughness of the microscopic surface and improved efficiency of the inkjet device, at levels nearly comparable to those of spin-coated patterns. A suitable hole transport layer (HTL) was also further developed as an interfacial material, prior to the solution processing of the emitter. The cross-linkable HTL was composed of triphenylamine as the cross-linking unit and a fluorene-based compound. At the optimized condition of the solvent formulation, printed droplets within 100 µm× 300 µm pixels formed a uniform stripe without remarkable coffee-ring defects and line-edge surface roughness.

Purpose The purpose of this study is to investigate the changes in the performance of ink formulations caused by the addition of compounds that improve the ink’s physical properties to achieve an optimum formulation for inkjet printing, because of the importance and simplicity of this method. Design/methodology/approach Ink samples were formulated using Acid Red 14 as ink colorant, different percentages of polymeric compounds including polyvinyl alcohol (PVA), polyvinylpyrrolidone and Carboxy methyl cellulose (CMC) as viscosity modifier compounds and surfactant as the surface tension enhancer. Formulated samples were adjusted in terms of fluid physical properties e.g. viscosity, density and surface tension, and the effect of used compounds on the improvement of both physical and colorimetric properties such as viscosity, surface tension, colorimetric coordinates and lightfastness has been evaluated to achieve the optimum printing inks to be printed on three different substrates. Findings The experimental observations showed that CMC was the most compatible compound as the viscosity modifier as its viscosity value was in the printable range of 2–22 cP. Moreover, a flow-curve test was applied to the ink samples and their Newtonian behavior was approved. Based on the spectrophotometric test results of printed samples, the samples containing PVA provided acceptable lightfastness in comparison to other ink samples on every used substrate. Originality/value An optimum relation between colorimetric coordinates of the printed samples and ink formulation could be considered and achieved.

Purpose The review glances upon the colorants used for printing on ceramic substrates by ink jet technology and techniques, chemistry involved during the selection of the colorants. Design/methodology/approach The ink jet technology is an easy and a convenient technique, specially designed colorants are used for such applications with tailor made properties and features. Findings New developments in technology and chemistry of colorants to achieve successes in application studies of ceramic substrates. Research limitations/implications N/A. Practical implications This review glances upon the history, development and practical approach of the current techniques with available dyes and pigments and the techniques involved during the synthesis and application. Originality/value The review paper provides information about the development of the inkjet technique on ceramics and available colorants with methods.

Combinatorial and high-throughput experimentation (HTE) is achieving more relevance in material design, representing a turning point in the process of accelerated discovery, development, and optimization of materials based on data-driven approaches. The versatility of drop-on-demand inkjet printing (IJP) allows performing combinatorial studies through fabrication of compositionally graded materials with high spatial precision, here by mixing superconducting REBCO precursor solutions with different rare earth (RE) elements. The homogeneity of combinatorial Y1−xGdxBa2Cu3O7 samples was designed with computational methods and confirmed by energy-dispersive Xray spectroscopy (EDX) and high-resolution X-ray diffraction (XRD). We reveal the advantages of this strategy in the optimization of the epitaxial growth of high-temperature REBCO superconducting films using the novel transient liquid-assisted growth method (TLAG). Advanced characterization methods, such as in situ synchrotron growth experiments, are tailored to suit the combinatorial approach and demonstrated to be essential for HTE schemes. The experimental strategy presented is key for the attainment of large datasets for the implementation of machine learning backed material design frameworks., The authors acknowledge the European Research Council for the ULTRASUPERTAPE project (ERC-2014-ADG-669504) and EU COST action for CA16218 (NANOCOHYBRI). We also acknowledge financial support from the Spanish Ministry of Economy and Competitiveness, and Spanish Ministry of Science, Innovation and Universities through the “Severo Ochoa” Program for Centers of Excellence in R&D (SEV-2015-0496 and CEX2019-000917-S), SUMATE project (RTI2018-095853-B-C21, co-financed by the European Regional Development Fund). Synchrotron SOLEIL is acknowledged for granting the beamtime (under project no. 20190274) and P. Joly for setup assistance at the DiffAbs beamline. We also acknowledge support from the Catalan Government with 2017-SGR-1519 and the energy Catalan network E4S. A.Q. thanks the Spanish Ministry of Science, Innovation and Universities for his “Juan de la Cierva” postdoctoral fellowship (Grant no. IJC2018-035034-I). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

Purpose Pretreatment of fabric with a number of chemicals and auxiliaries is a prerequisite for inkjet printing. Owing to the rapidly increasing use of inkjet printing for textile fabrics, the study of the effects of process variables on various characteristics of the resulting print has drawn considerable interest recently. The purpose of this paper is to study the effects of different variables associated with the inkjet printing process on the quality of the resulting print. Specifically, the effects of chemicals and auxiliaries used in the pretreatment of the fabric prior to printing and factors such as steaming time were studies. Design/methodology/approach In the present study, which forms a part of a larger study by the authors, the influence of the nature of thickener, the amounts of thickener, urea and alkali, pH of the pretreatment liquor and the duration of steaming on ink penetration into the printed fabrics and the ink spreading across the fabrics was studied. The nature of ink penetration and ink spreading are known to have pronounced effects on the quality and, in turn, the overall appearance of the resulting print. A set of experiments based on a blocked 25–1 fractional factorial design with four centre points were conducted to evaluate the role of the aforementioned five variables. Ink penetration was quantified on the basis of the principles of Kebulka-Munk theory while ink spreading was analysed by image analysis. Findings Detailed statistical analyses of the experimental data obtained show that different thickeners perform differently and can have a marked influence on ink penetration and ink spreading. In the case of polyacrylic acid-based thickener, changing the levels of the factors has a marked effect on ink penetration and in-turn on ink spreading. In the case of polyacrylamide (PAM)-based thickener, on the other hand, the effect of changing the levels of various factors on the ink penetration and ink spreading is considerably less pronounced. In addition, PAM treated samples exhibited better performance in terms of ink penetration and spreading. Originality/value This study provides useful information for textile printers and highlights the importance of selecting the right type of thickener to make the printing process and the quality of the resulting print more predictable and controllable.

Sample library preparation is a central step in the process of evaluating materials with the general aim of efficient library formulation while minimizing resource consumption. We demonstrate here the first implementation of a microfluidic-enabled thin film sample library formulation platform with integrated inkjet printing capability for directly patterning these libraries with reduced material wastage. System development and general performance screening protocol for these patterned thin films are described. We study the combinatorial formulation capabilities of this system by focusing on some practical case studies for probing the electrical conductivity in organic, biocompatible and electroactive polymer/additive (PEDOT:PSS/DMSO and PEDOT:PSS/EG) blends. Functionally-graded thin film libraries are prepared by mixing ink components and directly dispensing the processed blends into programmed geometries using the integrated platform. Electrical and morphological characterization of these printed thin film libraries is conducted to validate the formulation efficacy of the platform. Interrogating these printed libraries, we were able to iteratively identify the location of conductivity maxima for the studied blends and corroborate the morphological basis of this enhancement with established theories.

The significant incidence of cancer on public health in the modern industrialized world is pushing the research on novel therapeutic techniques and diagnosis tools. The latter, in particular, are of vital importance, since in many cases a prompt cancer diagnosis can significantly decrease patient’s mortality. Bioimpedance tissue analysis, in particular, is gaining attention as a promising methodology to identify tumor. Manufacturing technologies for bioimpedance probes are however still not completely adapt for cost effective mass production. In this context, the present work aims at producing a costless bioimpedance sensor by employing inkjet printing and electrolytic metal deposition. The probe manufactured in this way is successfully employed for bioimpedance testing of three animal tissues, demonstrating ability to successfully distinguish between them.

For drop-on-demand (DOD) inkjet printing, stable and single ink droplet formation without satellite dots is the key to improve the print quality. The formation of stable and single droplet is influenced by filament break up and the polymer chain’s coil–stretch transition behavior. In this paper, the droplet formation behaviors of polyfluorene (PFO) ink at various driving voltages (V), polymer chain’s coil–stretch transition mechanism and its effects on single ink droplet formation are investigated. It indicates that when 58 63 V, Wi > 0.5, the PFO molecular chain is stretched because of the high hydrodynamic forces, resulting unwanted satellite droplets. When 55

In this work, Pt-doped In2O3 nanoparticles (Pt-In2O3) were inkjet printed on a FET-type sensor platform that has a floating gate horizontally aligned with a control gate for humidity detection at room temperature. The relative humidity (RH)-sensing behavior of the FET-type sensor was investigated in a range from 3.3 (dry air in the work) to about 18%. A pulsed measurement method was applied to the transient RH-sensing tests of the FET-type sensor to suppress sensor baseline drift. An inkjet-printed Pt-In2O3 resistive-type sensor was also fabricated on the same wafer for comparison, and it showed no response to low RH levels (below 18%). In contrast, the FET-type sensor presented excellent low humidity sensitivity and fast response (32% of response and 58 s of response time for 18% RH) as it is able to detect the work-function changes of the sensing material induced by the physisorption of water molecules. The sensing mechanism of the FET-type sensor and the principle behind the difference in sensing performance between two types of sensors were explained through the analysis on the adsorption processes of water molecules and energy band diagrams. This research is very useful for the in-depth study of the humidity-sensing behaviors of Pt-In2O3, and the proposed FET-type humidity sensor could be a potential candidate in the field of real-time gas detection.

Multinozzle printing processing with the fabrication of a functional material film lays the foundation for the development of efficient scale production of a photoelectric device. However, a prominent challenge is how to realize the volume uniformity of the droplets. Here, a classical analysis method is introduced first by printing poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) to analyze the behavior of droplets. It relies on a variance calculation for the clarification of the law of implicit behavior of droplets in terms of digitizing. This method reveals the effect of printing parameters on the uniformity of the volume of droplets in multinozzle printing. Overall, by combining both ink formulations and printing parameter optimization, it is concluded that the minimum volume variance of nozzles with different numbers is less than 0.5% and the influence of various parameters in multinozzle printing is found to be ranked. The feasibility of this analysis method is presented and is of great significance to achieving a very stable, large-scale multinozzle printing device.

Cotton fabric has been extensively used as the substrate of inkjet printing to manufacture traditional garments as well as emerging e-textiles due to its comfort, renewability, good dyeability, biodegradability and relatively low cost. In present work, the spreading and coalescence of ink drops on a cotton fabric as well as their effects on the image quality were investigated. A reactive orange 13 dye was selected as the colorant to make it convenient to observe the depositing morphologies of ink drops. The impacting and wetting processes of an ink drop on a cotton fiber were observed through a high-speed camera. Depositing morphologies of an ink drop, coalescing structures of ink drops and patterns printed with different drop spacings were observed through a microscope. The results show that the ink drop stably deposited on the cotton fabric and formed a long strip pattern after wetting. That indicates the inkjet printing pattern on a cotton fabric should be composed of “line segments” instead of round points. The edges of the pattern printed with a small drop spacing appeared bleeding phenomenon due to the ink drops excessively accumulated on the gaps between cotton fibers. Ink drops could not coalesce at a large drop spacing resulting in the printed pattern being discontinuous. The ideal pattern was printed at an intermediate drop spacing, which was 20 µm in this experiment.

Evaporative deposits from drops are widely studied due to their numerous applications in low-effort self-assembly, including for inkjet printing, microscale separations, and sensing/diagnostics. This phenomenon has been broadly explored for drops containing suspended colloidal particles but has been less quantified for drops with dissolved solutes. When a drop of solute/solvent mixture is evaporated on a substrate, nonvolatile solutes become supersaturated as the solvent evaporates, which then leads to crystal nucleation at the substrate-drop contact line. Emerging crystals alter the local wettability and fundamentally alter the dynamics of evaporation, which, in turn, influences the resultant evaporative deposit. Here we investigate the role of interactions between the substrate, crystals, and solution by comparing the evaporative deposition of three different salts as solutes against an evaporating colloidal solution. We show that nucleation effects can cause crystalline deposits to have a temperature relationship that is opposite to that of colloidal deposits and demonstrate how a balance between the contact-line pinning force and nucleation controls the deposit size.

Inkjet printing method is one of the most effective ways for fabricating large-area perovskite solar cells (PSCs). However, because ink crystallizes rapidly during printing, the printed perovskite film is discontinuous with increasing defects. It severely restricts the application of the inkjet printing technology to the fabrication of perovskite photovoltaic devices. Here, we designed a new mixed-cation perovskite ink system that can controllably retard the crystallization rate of perovskite. In this new ink system, the printing solvent is composed of n-methyl pyrrolidone (NMP) and dimethyl formamide (DMF), and PbX2 is replaced by PbX2-DMSO (X = Br, I) complex as a printing precursor to create a high-quality perovskite layer. Accordingly, the printed Cs0.05MA0.14FA0.81PbI2.55Br0.45 perovskite film exhibited high homogeneity with a large grain size (over 500 nm). Besides, the printed perovskite film possessed lower defects with improved carrier lifetime compared to the control sample. Combining these advantages, the printed PSC delivers decent power conversion efficiencies (PCEs) of 19.6% (0.04 cm2) and 17.9% (1.01 cm2). The large-area device can still retain its original efficiency of 89% when stored in air with humidity less than 20% for 1000 h.

In textile inkjet printing, understanding the effect of viscosity and surface tension of a reactive dye ink on droplet formation is of great significance. As an organic ecofriendly solvent, polyethylene glycol with a molecular weight of -400 g/mol (PEG400) was used to prepare reactive dye inks with or without Surfynol 465 (S465) to explain separately how viscosity and surface tension affect the droplet formation of a reactive dye ink. The intermolecular interactions in the ink and physical properties of the ink were investigated by measuring the visible absorption spectra, hydrodynamic radius, viscosity, and surface tension. Droplet formation under a single variable influence of viscosity or surface tension was observed by taking photographs using a high-speed camera. Results show that a high ink viscosity condition generates no satellite droplet formation and a slower droplet velocity, and a higher surface tension tends to cause ligament rupture from the nozzle tip and the droplet. Moreover, a twill cotton fabric printed using the PEG-S465-dye ink at a 30% PEG400 concentration showed higher ink penetration, dye fixation rate, ideal color strength, and rubbing fastness.

Anticounterfeiting techniques based on physical unclonable functions exhibit great potential in security protection of extensive commodities from daily necessities to high-end products. Herein, we propose a facile strategy to fabricate an unclonable super micro fingerprint (SMFP) array by introducing in situ grown perovskite crystals for multilevel anticounterfeiting labels. The unclonable features are formed on the basis of the differential transportation of a microscale perovskite precursor droplet during the inkjet printing process, coupled with random crystallization and Ostwald ripening of perovskite crystals originating from their ion crystal property. Furthermore, the unclonable patterns can be readily tailored by tuning in situ crystallization conditions of the perovskite. Three-dimensional height information on the perovskite patterns are introduced into a security label and further transformed into structural color, significantly enhancing the capacity of anticounterfeiting labels. The SMFPs are characterized with tunable multilevel anticounterfeiting properties, including macroscale patterns, microscale unclonable pattern, fluorescent two-dimensional pattens, and colorful three-dimensional information.

We present a high resolution, ultra-frugal printing of paper microfluidic devices using in-house paraffin formulation on a simple filter paper. The patterns printed using an office inkjet printer formed a selective hydrophobic barrier of 4 ± 1 µm thickness with a hydrophilic channel width of 275 µm. These printed patterns effectively confine common aqueous solutions and solvents, which was verified by solvent compatibility studies. SEM analysis reveals that the solvent confinement is due to pore blockage in the filter paper. The fabricated paper-based device was validated for qualitative assessment of Candida albicans (pathogenic fungi) by using a combination of L-proline β-naphthylamide as the substrate and cinnamaldehyde as an indicator. Our studies reveal that the pathogenic fungi can be detected within 10 min with the limit of detection (LOD) of 0.86 × 106 cfu/mL. Owing to its simplicity, this facile method shows high potential and can be scaled up for developing robust paper-based devices for biomarker detection in resource-limited settings. Graphic abstract

Objective: The inkjet printing (IP) and fused deposition modeling (FDM) technologies have emerged in the pharmaceutical field as novel and personalized formulation approaches. Specific manufacturing factors must be considered in each adopted methodology, i.e. the development of suitable substrates for IP and the incorporation of highly thermostable active pharmaceutical compounds (APIs) for FDM. In this study, IP and FDM printing technologies were investigated for the fabrication of hydroxypropyl methylcellulose-based mucoadhesive films for the buccal delivery of a thermolabile model drug.Significance: This proof-of-concept approach was expected to provide an alternative formulation methodology for personalized mucoadhesive buccal films.Methods: Mucoadhesive substrates were prepared by FDM and were subjected to sequential IP of an ibuprofen-loaded liquid ink. The interactions between these processes and the performance of the films were evaluated by various analytical and spectroscopic techniques, as well as by in vitro and ex vivo studies.Results: The model drug was efficiently deposited by sequential IP passes onto the FDM-printed substrates. Significant variations were revealed on the morphological, physicochemical and mechanical properties of the prepared films, and linked to the number of IP passes. The mechanism of drug release, the mucoadhesion and the permeation of the drug through the buccal epithelium were evaluated, in view of the extent of ink deposition onto the buccal films, as well as the distribution of the API.Conclusions: The presented methodology provided a proof-of-concept formulation approach for the development of personalized mucoadhesive films.

Capillary-driven ink infiltration through a porous powder bed in three-dimensional (3D) binder jet printing (inkjet printing onto a powder bed) controls the printing resolution and as-printed “green” strength of the resulting object. However, a full understanding of the factors controlling the kinetics of the infiltration remains incomplete. Here, high-resolution in situ synchrotron radiography provides time-resolved imaging of the penetration of an aqueous solution of eythylene glycol through a porous alumina powder bed, used as a model system. A static drop-on-demand inkjet printer was used to dispense liquid droplets onto a powder surface. The subsequent migration of the liquid front and its interactions with powder particles were tracked using fast synchrotron X-radiography in the Diamond Synchrotron, with phase-contrast imaging at a frame rate of 500 Hz. Image processing and analysis reveal that both the time-dependent increment in the wetting area and the propagation of the “interface leading edge” exhibit heterogeneous behavior in both temporal and spatial domains. However, mean infiltration kinetics are shown to be consistent with existing infiltration models based on the Washburn equation modified to account for the spreading of the liquid drop on the powder surface and using a modified term for the bed porosity.

Lead halide perovskite nanocrystals (NCs) have shown remarkable properties for emission applications, but their toxicity and instability are a hindrance to many commercial uses. Herein, we report t...

A quantum dots optical fiber (QDOF) sensor is proposed for temperature sensing in this paper. The sensor is fabricated by the drop-on-demand inkjet printing technology. By controlling the diameter of droplet, the spacing between droplets and the number of printed layers, the QDOF is printed on the polymer substrate. The loss of QDOF is less than 0.35 dB·mm-1 at the fluorescence wavelength. The experimental results show that the temperature sensitivity of sensor is 109 pm/ °C. As far as we know, this is the first time that a QDOF sensor is manufactured by the inkjet printing technology to realize the temperature measurement.

The use of nanocelluloses is being conducted for the most diverse applications. Their performance as coating agent has been mainly explored to improve barrier properties, as they emerge as perfect candidate for plastic substitution, but it is also important to explore their potential to improve printing quality. In the present work, the influence of different nanocelluloses, obtained through mechanical, enzymatic, TEMPO-mediated oxidation and carboxymethylation treatments, in the coating process and inkjet printability of office papers was assessed. The results revealed that the cellulose nanofibrils are better for printability than the microfibrils. But the size and charge of the former must be taken into account, since fibrils of very small size penetrate the paper structure, dragging the pigments from the surface, and very anionic nanofibrils can also have negative influence on the optical density. Besides, an interesting synergy between surface-sizing starch and the cellulose nanofibrils was found to occur as the latter closed the paper structure, which prevented starch from penetrating, while potentiating both of their positive effects on ink pigment entrapment. An additional study of characterization of inkjet pigments was also performed.

The thinning strategy is effective to develop high-performance solid oxide fuel cells (SOFCs) that can operate at low temperatures. The inkjet printing, which enables precise thin-film production i...

This letter proposes a procedure for the rapid prototyping and on-demand manufacturing of thin film flexible electro-adhesive devices (EADs) made with a commercial polyimide dielectric layer, inkjet printed interdigitated silver electrodes and blade coated silicone elastomer encapsulation backing. As a proof demonstration, flexible thin-film EADs featuring 9.6 cm2 active area, 315 μm thickness and 0.7 g weight have been manufactured and tested over different adhering substrates showing peak adhesive shear stresses of up to 56.67 kPa, fast response time (11 ms for initial activation and 0.3 s for full electrification) and little energy requirements (from 1.3 mJ for initial activation to 20 mJ for full electrification and with a subsequent power consumption of about 1 mW for long-term grasp holding). Practical application of the manufactured EADs within a gripper for the grasping and handling of real objects that include a glass bottle, a hollow carbon fiber tube, a cardboard box, a box with thin polypropylene envelope and a polypropylene bottle is also demonstrated.

The rising demand for eradicating hazardous substances in the workplace has motivated vigorous researches on environmentally sustainable manufacturing processes of colloidal quantum dots (QDs) for their optoelectronic applications. Despite remarkable achievements witnessed in QD materials (e.g., Pb- or Cd-free QDs), the progress in the eco-friendly process is far falling behind and thus the practical use of QDs. Herein, a complete "green" process of QDs, which excludes environmentally unfriendly elements from QDs, ligands, or solvents, is presented. The implant of mono-2-(methacryloyloxy)ethyl succinate (MMES) ligands renders InP/ZnSexS1-x QDs dispersed in eco-friendly polar solvents that are widely accepted in the industry while keeping the photophysical properties of QDs unchanged. The MMES-capped QDs show exceptional colloidal stabilities in a range of green polar solvents that permit uniform inkjet printing of QD dispersion. In addition, MMES-capped QDs are also compatible with commercially available photo-patternable resins, and the cross-linkable moiety within MMES further facilitates the achievement in the formation of well-defined, micrometer-scale patterning of QD optical films. The presented materials, all composed of simple, scalable, and environmentally safe compounds, promise low environmental impact during the processing of QDs and thus will catalyze the practicable use of QDs in a variety of optoelectronic devices.

For nano-cellulose materials, which have attracted attention in both academia and industry in recent years, to be used as a truly valuable material class, the author believes that their processing procedures must be both rational and simple. In addition, it is important to focus on areas where the outcomes cannot be achieved without these particular nanomaterials. These points also apply to nanomaterials obtained from the animal structural polysaccharide chitin. On this basis, the author’s group has recently achieved “creation of micro-patterning cell culture substrate by inkjet printing of chitinous nanocrystals” and “utilization of cellulose nanofibers as a module for microfluidic paper-based analytical device (μPAD)”. The direction of these projects also reflects some of the activities of the applied life science department that the author worked for until recently. Cellulosic materials, including traditional forms for industrial use, often exist as a powder state at some point in the production process. The author hopes that research on nano-cellulose and nano-chitin will be enhanced through collaboration with powder technology researchers.

Many arthropods have compound eyes, which are made up of numerous separate visual units (microlenses) or ommatidia. These natural compound eyes have exceptional optical properties such as wide field of view (FOV), low aberration, and fast motion tracking capability. In this paper, a large-scale artificial compound eye (ACE) is fabricated efficiently using a combination of inkjet printing and air-assisted deformation processes. Both size and geometry of the microlens are controlled via superposed drops on the substrate. The simulation results show that the light intensity of the ACE follows a systematic distribution for tilted incident light, which represents a significant improvement, compared to planar distributed microlenses. We then manufacture ACEs with different heights and diameters, and their FOVs are compared with the theoretically predicted results. The measured FOV was 50°-140°. The acceptance angles for the different ACEs are determined, and their relationship with the ratio of height to radius (H/r) of the microlens is investigated in more detail. Furthermore, the imaging properties of the microlenses with different angles of incidences are studied, which suggest a FOV up to 140° and an acceptance angle of about 50°. The microlens captures images even at an angle of incidence of about 60°. The corresponding distortion in both the

In recent years, additive manufacturing of polydimethylsiloxane (PDMS) has gained interest for the development of soft electronics. To build complex electrical devices, fabrication of multilayered structures is required. We propose here a straightforward digital printing fabrication process of silicone rubber-based, multilayered electronics. An inkjet-printable PDMS solution was developed for the digital patterning of elastomeric structures. The silicone ink was used together with a highly conductive silver nanoparticle (Ag NP) ink for the fabrication of all-inkjet-printed multilayered electrical devices. The application of the multilayered circuit board was successful. The sheet resistances were below 0.3 ω/□, and the conductive layer thickness was less than 1 μm. The electrical insulation between the conductive layers was done by printing a 20-25 μm-thick dielectric PDMS layer selectively on top of the bottommost conductive layer. publishedVersion

The use of Chipless RFID tags has been increasing for many applications, especially for structural health monitoring (SHM) applications where they are either affixed or embedded in materials and structures. The practical utility of chipless RFID is dependent upon the ability to manufacture tags in a cost-effective manner. One approach for achieving this is through the use of an inkjet printer and conductive ink. However, in order to harness the benefits of printed tags, it is necessary to know the dielectric properties of the substrates on which the tags are printed, as well as the conductivity of the printed conductors (i.e., ink) so that the tags can be properly simulated using electromagnetic (EM) models. It is also necessary to understand the performance differences that occur when tags are manufactured via inkjet-printing vs. when they are manufactured as printed circuit boards (PCBs). This work presents the dielectric property measurement results for three different paper substrates commonly used in tag printing from X-band (8.2 – 26.5 GHz) to K-band (18 - 26.5 GHz). Additionally, conductivity measurement results for silver nano-particle inkjet-printed conductors are also reported. These dielectric property and conductivity parameters are then used in tag EM simulations, and in the future when they are applied for SHM applications. PCB and printed tags are manufactured and measured to compare their performance both to each other and to simulation results.

Drop on demand (DoD) inkjet printing is a high precision, non-contact, and maskless additive manufacturing technique employed in producing high-precision micrometer-scaled geometries allowing free design manufacturing for flexible devices and printed electronics. A lot of studies exist regarding the ink droplet delivery from the nozzle to the substrate and the jet fluid dynamics, but the literature lacks systematic approaches dealing with the relationship between process parameters and geometrical outcome. This study investigates the influence of the main printing parameters (namely, the spacing between subsequent drops deposited on the substrate, the printing speed, and the nozzle temperature) on the accuracy of a representative geometry consisting of two interdigitated comb-shape electrodes. The study objective was achieved thanks to a proper experimental campaign developed according to Design of Experiments (DoE) methodology. The printing process performance was evaluated by suitable geometrical quantities extracted from the acquired images of the printed samples using a MATLAB algorithm. A drop spacing of 140 µm and 170 µm on the two main directions of the printing plane, with a nozzle temperature of 35 °C, resulted as the most appropriate parameter combination for printing the target geometry. No significant influence of the printing speed on the process outcomes was found, thus choosing the highest speed value within the investigated range can increase productivity.

Inkjet printing (IJP) is a very appealing cost-effective deposition technique to achieve large-area solution-derived functional films. For many applications, it is very challenging to increase the film thickness in order to achieve competitive performance, for instance, high critical currents in superconducting films. In this paper, the preparation of superconducting YBa2Cu3O7 thick films (∼1.1 μm) using a single deposition is reported. Specific rules for ink design, deposition protocols, and pyrolysis processes are provided. The most important aspect is to formulate an ink with a solvent having a high boiling point that keeps the whole film wet during deposition to avoid liquid movement due to coffee-ring effects. An additional success has been to modify the ink with a photocurable polyacrylic ester varnish which after polymerization with a UV LED lamp helps keep homogeneous thickness. This varnish also helped avoid the generation of film instabilities (wrinkling or cracking) during pyrolysis. Homogeneous pyrolyzed thick films are transformed into epitaxial thick films with high critical currents. The IJP process is shown to be valid to prepare nanocomposite films using colloidal inks including pre-prepared BaZrO3 nanoparticles. The nanocomposite thick films display enhanced vortex pinning, thus keeping high critical currents under high magnetic fields., The authors acknowledge the EUROTAPES project (EU-FP7 NMP-LA-2012-280432), COACHSUPENERGY (MAT2014- 51778-C2-1-R and MAT2014-51778-C2-2-R), SUMATE (RTI2018-095853-BC21 and RTI2018-095853-B-C22) cofinanced by the European Regional Development Fund and SUPERINKS (RTC-2015-3840-S) from MINECO (cofinanced by the European Regional Development Fund), 2017-SGR 753 from Generalitat de Catalunya, and COST Action NANOCOHYBRI (CA16218). ICMAB authors acknowledge the Center of Excellence awards Severo Ochoa SEV2015-0496 and CEX2019-000917-S. The authors acknowledge the Scientific Services at ICMAB, ICN2 Electron Microscopy Division, and LMA-INA from Aragon. They also acknowledge KAO Chimigraf for providing varnishes and Bruker HTS for providing metallic substrates.

3D printing is among the most exciting and rapidly advancing fields of research in materials engineering and device fabrication. The capability of developing a bottom-up approach to device fabricat...

Attractive ion–ion interactions allow trapping the tetracationic host cyclobis(paraquat-p-phenylene) (CBPQT4+) within solid matrices composed of negatively charged scaffolds, namely cellulose nanocrystals (CNCs). Through this supramolecular approach, we have fabricated CNC-CBPQT4+ films that change color upon sequenced guest uptake-molecular recognition. The evolution of color is conditioned to the selection of a guest and the self-assembly of an in-film host–guest complex. Here, we have used films and guests as synergetic paper and ink materials to generate responsive text and patterns that transform (disappear, change color, etc.) upon stimulation (temperature, pH, or competitive guests). This concept could be utilized for anticounterfeiting purposes, responsive inkjet printing, data encryption/decryption, and time-evolving patterns.

Although there are currently different applications for gallium in microelectronics, literature is sparse about its applications in the area of conductive inks. The important characteristics to consider from the ink are viscosity, corrosion and surface tension. The importance of viscosity is a critical parameter in the printing ink mixture, which requires a metal to fulfill the function of conductor, such as gold, copper, and silver. Gallium as a conductor replacement is proposed due to the high cost of such metals currently used. The valence electrons are discussed in this paper due to the direct relation that has with metal conductivity, to provide a justified analysis about gallium application in conductive ink. The application of gallium could mean a significant change in conductive ink elaboration process. Thus, the aim of this research is to analyze the application of gallium as conductive ink, which is done by a literature review on gallium as a semi-conductor because of his valence electrons. Results about gallium as a potential conductive ink show that there is evidence that gallium shares similar properties as the current of materials conductive inks being adopted. This first literature review has some implications on the potential use of gallium as a conductive ink, requiring further experimental research to better test for conducting efficiency.

Customizable solar cells are required for aesthetic indoor and outdoor photovoltaic deployment as well as for the freedom of design of small and portable power supplies. We demonstrate that drop on demand inkjet printing can be used for the fabrication of monolithic mesoscopic carbon-based perovskite solar cells by printing all of the oxide layers in the stack as well as the organo-metal halide absorber. Printable inks using environmentally friendly solvents and jetting parameters were developed in order to achieve homogenous and continuous functional layers of the photovoltaic stack. Inkjet printed cells are compared to those obtained from the standard screen-printing route. As a proof of principle, photovoltaic cells with an area of 1.5 cm2 and a performance of 9.1% were realized by inkjet printing, which opens up intriguing application possibilities.

The wide spread of smartphones and QR codes for various end-user applications has had an impact beyond traditional fields of use, recently also reaching point-of-care testing (POCT). This work presents the integration of QR code recognition into paper-based analytical devices (PADs) with "distance-based" colorimetric signalling, resulting in semiquantitative readout fully relying on straightforward barcode reader solutions. PADs consist of an array of QR codes arranged in series inside a paperfluidic channel. A mask dye concept has been developed, which enables utilisation of colour changing indicators by initially hiding QR codes. The colour change of the indicator induced by the presence of an analyte of interest results in gradual unmasking of QR codes, which become recognisable by the smartphone barcode reader app. To reproducibly fabricate devices, all fabrication steps were performed by commercial desktop solid ink and inkjet printing. The QR code masking function was optimised by controlling the amount of printed mask dye through adjusting the opacity of printing patterns during the inkjet deposition process. For proof-of-concept, a model assay in the form of colorimetric copper ion (Cu2+) detection in the concentration range of 0.4 mM to 3.2 mM was evaluated. Consistent results independent of the smartphone model and environmental light condition were achieved with a free barcode reader app. To the best of our knowledge, this work is the first demonstration of a semiquantitative assay approach fully relying on QR code readout without digital colour analysis, customised app or hardware modification.

Reported herein is a stretchable strain-tolerant soft printed circuit board (SPCB) following optimized circuit design rules. Inkjet-printed interconnects with a wrinkled structure and rigid epoxy patterns allow the outstanding stretchability and strain distribution controllability of the SPCB, respectively. The prototype circuits show reliable operation under various mechanical deformations, even in the 180° folding state and the irregular deformed state with 25% tensile strain. This research paves a promising route for the realization of highly reliable soft printed circuits with a high degree of design freedom, which can thus be used for driver chip mounting or driver board interconnection for the stretchable display applications.

For device printing, it is important for uniform films to be printed because the morphology of the film affects the performance of the device in inkjet printing. In this study, to prepare stable and well-dispersed ink, polyacrylate and silicone surfactant BD-3033H were added to ink. Then a uniform quantum dot (QD) film was obtained by optimizing the polyacrylate and silicone surfactant contents of the ink as well as the substrate temperature. The change of the polyacrylate structure from a curly chain structure to a three-dimensional network structure blocked the outward flow of QDs. Silicone surfactant BD-3033H caused Marangoni flow and made the QDs flow inward. When the substrate temperature was increased, the solvent evaporation rate was accelerated, the contact line was pinned, and the outward flow was enhanced, which changed the film structure from convex to flat. Finally, when the polyacrylate content was 12 wt%, the silicone surfactant BD-3033H content was 0.10 wt%, the substrate temperature was 40°C, and the coffee ring effect was eliminated. A uniform QD film was printed, providing a technical guarantee for the fabrication of QD devices in the future.

Reactive inkjet printing holds great prospect as a multimaterial fabrication process because of its unique advantages involving customization, miniaturization, and precise control of droplets for patterning. For inkjet printing of hydrogel structures, a hydrogel precursor (or cross-linker) is printed onto a cross-linker (or precursor) bath or a substrate. However, the progress of patterning and design of intricate hydrogel structures using the inkjet printing technique is limited by the erratic interplay between gelation and motion control. Accordingly, microreactive inkjet printing (MRIJP) was applied to demonstrate a spontaneous 3D printing of hydrogel microstructures by using alginate as the model system. In addition, a printable window within the capillary number-Weber number for the MRIJP technique demonstrated the importance of velocity to realization of in-air binary droplet collision. Finally, systematic analysis shows that the structure and diffusion coefficient of hydrogels are important factors that affect the shape of printed hydrogels over time. Based on such a fundamental understanding of MRIJP of hydrogels, the fabrication process and the structure of hydrogels can be controlled and adapt for 2D/3D microstructure printing of any low-viscosity (

The inorganic core-shell pigment CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} was synthesized using a sol-gel method, and the pigment was applied as a surface coating on inkjet paper to study the influence of inorganic core-shell pigments on the dynamic permeability, surface properties, optical properties and inkjet-printing performance of coated paper. CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} prepared using carboxymethyl cellulose (CMC) had better coverage than that prepared using polystyrene sodium sulfate (PSS) dispersant. The CMC-prepared CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} -a had improved dispersibility, and the solids content of the coating reached 35 %. Inorganic core-shell pigments improve the surface and optical properties of the coated paper, making them similar to those of a reference calcium carbonate-coated paper. The smoothness and gloss improved by 60.8 % and 78.4 %, respectively, compared with those of silica-coated paper. The inkjet solid density and dot definition increased by 28.8 % and 4.1 %, respectively, compared with those of the calcium carbonate-coated paper. Preparing inorganic core-shell pigment CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} is an effective method to fabricate inkjet printing coatings with advantageous microstructures for ink absorption.

Additive manufacturing has dramatically transformed the design and fabrication of advanced objects. Printed electronics-an additive thin-film processing technology-aims to realize low-cost, large-area electronics, and fabrication of devices with highly customized architectures. Recent advances in printing technology have led to several innovative applications; however, layer-on-layer deposition persists as a challenging issue. Here, the additive manufacturing of functional oxide devices by inkjet printing is presented. Two conditions appear critical for successful layer-on-layer printing: (i) preservation of stable surface properties and (ii) suppression of the material accumulation at the edges of a feature upon drying. The former condition was satisfied by introducing a surface modification layer of a polymer with nanotextured topography, and the latter was satisfied by designing the solvent composition of the ink. The developed process is highly efficient and enables conformal stacking of functional oxide layers according to the user-defined geometry, sequence arrangement, and layer thickness. To prove the effectiveness of this concept, we demonstrate an additive manufacture of all-oxide ferroelectric multilayer capacitors/transducers. Printed multilayer devices offer a significant increase in the capacitance density and the electromechanical voltage response in comparison to the single-layer devices. Further growth in the number of available functional oxide inks will enable arbitrary device architectures with novel functionalities.

The purpose of this study was to investigate the application of piezoelectric inkjet technology in the preparation of custom-made indomethacin (IMC) films. Indomethacin solutions with and without PVP were printed onto polymeric sheets using a commercial inkjet printer. Drug loading was varied by selecting a machine parameter different dots per inches (DPIs). The printed patches were evaluated for particulate morphologies, drug loading

Nowadays there is a worldwide growing interest in the Inkjet Printing technology owing to its potentially high levels of geometrical complexity, personalization and resolution. There is also social concern about usage, disposal and accumulation of plastic materials. In this work, it is shown that sugar-based biodegradable polyurethane polymers exhibit outstanding properties as polymer-matrix for gold nanoparticles composites. These materials could reach exceptional stabilization levels, and demonstrated potential as novel robust inks for Inkjet based Printing. Furthermore, a physical comparison among different polymers is discussed based on stability and printability experiments to search for the best ink candidate. The University of Seville logo was printed by employing those inks, and the presence of gold was confirmed by ToF-SIMS. This approach has the potential to open new routes and applications for fabrication of enhanced biomedical nanometallic-sensors using stabilized AuNP. Spanish Ministerio de Economía y Competitividad MINECO, (Grants Nos. CTQ2016- 78703-P and MAT2016-78703-P) Junta de Andalucía (Consolidation Grant for Research Group FQM135 and 2017/FQM-386, P-2018/809) University of Seville (V y VI Plan Propio PP2016-5937)

Firm immobilization of catalysts on the predesigned position over substrates is an essential process for producing flexible circuits by the electroless deposition (ELD) process. In this work, a com...

Realization of luminescent carbon dots (CDs) in the solid state has been a critical issue for their applications in various fields, such as optoelectronic devices and inkjet printing. However, lumi...