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Inkjet printing is a more sustainable and scalable fabrication method than spin coating for producing perovskite solar cells (PSCs). Although spin-coated SnO2 has been intensively studied as an effective electron transport layer (ETL) for PSCs, inkjet-printed SnO2 ETLs have not been widely reported. Here, we fabricated inkjet-printed, solution-processed SnOx ETLs for planar PSCs. A champion efficiency of 17.55% was achieved for the cell using a low-temperature processed SnOx ETL. The low-temperature SnOx exhibited an amorphous structure and outperformed high-temperature crystalline SnO2. The improved performance was attributed to enhanced charge extraction and transport and suppressed charge recombination at ETL/perovskite interfaces, which originated from enhanced electrical and optical properties of SnOx, improved perovskite film quality, and well-matched energy level alignment between the SnOx ETL and the perovskite layer. Furthermore, SnOx was doped with Cu. Cu doping increased surface oxygen defects and upshifted energy levels of SnOx, leading to reduced device performance. A tunable hysteresis was observed for PSCs with Cu-doped SnOx ETLs, decreasing at first and turning into inverted hysteresis afterwards with increasing Cu doping level. This tunable hysteresis was related to the interplay between charge/ion accumulation and recombination at ETL/perovskite interfaces in the case of electron extraction barriers.

[Display omitted] Energy storage devices are progressively advancing in the light-weight, flexible, and wearable direction. Ti 3 C 2 T x flexible film electrodes fabricated via a non-contact, cost-effective, high-efficiency, and large-scale inkjet printing technology were capable of satisfying these demands in our previous report. However, other MXenes that can be employed in flexible energy storage devices remain undiscovered. Herein, flexible V 2 CT x film electrodes (with the low formula weight vs Ti 3 C 2 T x film electrodes) with both high capacities and excellent photoelectric properties were first fabricated. The area capacitances of V 2 CT x film electrodes reached 531.3–5787.0 μF⋅cm−2 at 5 mV⋅s−1, corresponding to the figure of merits (FoMs) of 0.07–0.15. Noteworthy, V 2 CT x film electrode exhibited excellent cyclic stability with the capacitance retention of 83 % after 7,000 consecutive charge–discharge cycles. Furthermore, flexible all solid-state symmetric V 2 CT x supercapacitor was assembled with the area capacitance of 23.4 μF⋅cm−2 at 5 mV⋅s−1. Inkjet printing technology reaches the combination of excellent photoelectric properties and high capacities of flexible V 2 CT x film electrodes, which provides a new strategy for manufacturing MXene film electrodes, broadening the application prospect of flexible energy storage devices. [ABSTRACT FROM AUTHOR]

Organic light emitting diodes (OLEDs) have progressed immensely, enabled by the different generations of light emitting materials. The latest generation of light emitting materials for OLEDs are the thermally activated delayed fluorescent (TADF) emitters and there has been significant effort in making solution processable TADF emitters, which has led to printable TADF OLEDs. This review provides an analysis of the current state‐of‐the‐art solution processed TADF OLEDs including white‐OLEDs. We find that fully solution processed TADF OLEDs, where all the organic layers are solution processed, account for only ≈4% of the reported solution processed TADF OLEDs. We also evaluate the progress of printed TADF OLEDs, examining the state‐of‐the‐art performances, different emissive materials and the similarities and differences in the device structures used. Our analysis reveals that the majority of the printing for TADF OLEDs is through inkjet printing and their emission peaks predominantly fall within the 500 nm to <600 nm. We conclude with proposals of potential areas for further research for the development of cheaper and scalable OLEDs. [ABSTRACT FROM AUTHOR]

Recent manufacturing of perovskite solar cells (PSC) is moving beyond a spin coating technique. Among several new methods of the large‐area PSCs, inkjet printing (IJP) has emerged as a promising alternative to spin coating due to the high degree of control on printed film area and low material waste. In the IJP of PSCs, one important question is how to remove redundant excess solvent and facilitate the crystallization of the perovskite phase. Along with IJP, an antisolvent bathing is employed. This work reports how the IJP parameters and antisolvent bathing compositions affect the microstructure and initial efficiency of inkjet‐printed PSCs. The halide perovskite films are submerged in the antisolvent of different temperatures to observe the formation of an intermediate phase and the evolution of perovskite phase. By observing the phase evolution using X‐Ray diffraction, an optimized antisolvent bath duration is achieved for diethyl ether (DE) condition. An enhanced power conversion efficiency (PCE) and larger grain size with two sequential passes of inkjet‐deposited perovskite are also reported, and the dissolution of homogeneous nucleation sites as a mechanism for larger grains is proposed. Finally, with multipass IJP and cold antisolvent DE bathing, a champion device with 15.02% PCE is achieved. [ABSTRACT FROM AUTHOR]

In recent years, inkjet digital printing technology has become a popular research area. This paper focuses on the spreading behavior of single ink drops on coated paper in digital inkjet printing. It explores the impact of ink drop spreading on monochromatic spectral reflectance, providing new insights for the theoretical development of spectral prediction models. The study involves constructing a spreading behavior model through theoretical modeling. Numerical simulations were conducted using the Volume of Fluid (VOF) method in Fluent software to assess the feasibility of the theoretical model. Finally, experimental fitting was used to validate the accuracy of the theoretical model. Considering the feathering effect in practical printing, a comprehensive monochromatic extended Clapper-Yule spectral prediction model was developed based on the spreading behavior of single ink drops. The prediction results of this model showed significant accuracy improvements in monochromatic spectral prediction compared to the traditional segmented Clapper-Yule model. This research offers new perspectives for spectral prediction and provides theoretical guidance for enhancing print image quality. [ABSTRACT FROM AUTHOR]

Wearable electronic textiles (e‐textiles) have emerged as promising healthcare solutions, offering point‐of‐care diagnostics while maintaining breathability, comfort, durability, and environmental stability with strong mechanical performance. However, the lack of thin and flexible power supplies hinders their practical adoption. In this regard, textile‐based micro‐energy storage devices present an appealing solution. Inkjet printing offers the capability to produce high‐quality prints with sharp details and versatile substrate compatibility, making it an ideal choice for a wide array of printing applications. Here, the preparation of a range of inkjet‐printable 2D material inks is reported for the fabrication of ultra‐flexible and machine‐washable textile micro‐supercapacitors. Then 2D material heterostructures are proposed to enhance the performance of textile supercapacitors. This study reveals that a unique combination of highly conductive graphene with an insulator hexagonal boron nitride (h‐BN) can enhance the areal capacitance of graphene‐based textile supercapacitors by ≈82.48%. The heterostructure‐based supercapacitors also demonstrate higher energy (≈18.06 µWh cm−2) and power densities (≈4333.33 µW cm−2) with excellent capacitance retention (≈95% after 1000 cycles). These findings on inkjet‐printed heterostructure‐based supercapacitors may herald a new era for the future application of high‐performance micro‐supercapacitors within textile‐based wearable technology. [ABSTRACT FROM AUTHOR]

This work presents a simple process for the development of flexible acetone gas sensors based on zinc oxide/graphene/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate). The gas sensors were prepared by inkjet printing, which was followed by a metal sparking process involving different sparking times. The successful decoration of ZnO nanoparticles (average size ~19.0 nm) on the surface of the graphene–PEDOT:PSS hybrid ink was determined by characterizations, including Raman spectroscopy, Fourier transform infrared spectroscopy, field-emission transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffractometry. The ZnO nanoparticle-decorated graphene–PEDOT:PSS with a sparking time of 2 min exhibited the highest response of 71.9% at 10 ppm of acetone, above those of samples treated with other sparking times and the undecorated control. In addition, the optimal sensor revealed high selectivity for acetone over several other kinds of gases, such as ammonia, toluene, dimethylformamide, ethanol, methanol, and benzene, at room temperature. The gas sensor also revealed a low limit of detection (0.4 ppm), high sensitivity (6.18 ppm−1), and high stability (5-week long-term) to acetone. The response and recovery times of the sensor were found to be 4.6 min and 4.2 min, respectively. The acetone-sensing mechanism was attributed to the formation of p-n heterojunctions, which were responsible for the significantly enhanced sensitivity. [ABSTRACT FROM AUTHOR]

Inkjet printing has emerged as a promising technique for patterning functional materials, offering significant advantages over traditional subtractive thin‐film methods. Its versatility enables the structuring of various materials, expanding application ranges and minimizing waste through additive manufacturing. However, the limited availability of functional material‐based inks suitable for inkjet printing presents challenges in ink formulation. HKUST‐1, a 3D cubic metal–organic frameworks (MOFs) comprised of copper(II) ions coordinated to benzene‐1,3,5‐tricarboxylate (BTC) organic linkers, known for its porosity and tunability, have potential to enhance inkjet‐printed devices. This study combines inkjet printing and evaporation‐induced crystallization to structure HKUST‐1, marking the first demonstration of nanocrystalline HKUST‐1 integrated into a printed electronic device, specifically a memristor, where the MOF is prepared by inkjet printing of a precursor solution. Memristors, which change their resistance based on the external stimuli history, enabling the construction of resistive random‐access memory (RRAM). The fabricated memristors in this study exhibit notable properties: low forming voltage, an Roff/Ron ratio of 104, a retention time of 600 s, and endurance exceeding 60 write and erase cycles. This research highlights the potential of integrating MOFs into inkjet printing, unlocking broader application possibilities, and advancing additive manufacturing for functional materials. [ABSTRACT FROM AUTHOR]

Microneedles are mainly used for pain-free drug administration and in biosensing for wearable systems. They are also promising for fields such as agronomy for precision farming, but their fabrication is not straightforward, often requiring expensive equipment and cleanroom protocols, being unsuitable for mass production. Here, we report a new and simple method for the scalable fabrication of all-inkjet-printed conductive microneedles based on silver nanoparticles (extensible to any other metallic nanoparticle ink) and a simple example of their application for monitoring the electrochemical properties of plants. [ABSTRACT FROM AUTHOR]

In the quest for sustainable and efficient solutions for modern electronics, flexible electronic devices have garnered global attention due to their potential to revolutionize various technological applications. The manufacturing of these devices poses significant challenges, particularly regarding environmental sustainability and ease of production. A novel method employing direct inkjet printing of silver nanoparticle (npAg) ink onto cellulose nanocrystal (CNC) substrates is presented, offering a promising alternative to conventional methods. This study demonstrates the ability of CNCs to serve as a flexible and biodegradable substrate that does not require complex post-printing treatments to achieve adequate electrical performance. This method was implemented in the fabrication of an electrowetting-on-dielectric (EWOD) device, achieving circuit patterns with high resolutions and reduced resistances. The findings not only validate the use of CNCs in flexible electronic applications but also underscore the potential of advanced printing techniques to develop flexible electronics that are environmentally sustainable and technically feasible. [ABSTRACT FROM AUTHOR]

In recent years, 3D printing has emerged as a promising technology in energy storage, particularly for the fabrication of Li-ion battery electrodes. This innovative manufacturing method offers significant material composition and electrode structure flexibility, enabling more complex and efficient designs. While traditional Li-ion battery fabrication methods are well-established, 3D printing opens up new possibilities for enhancing battery performance by allowing for tailored geometries, efficient material usage, and integrating multifunctional components. This article examines three key 3D printing methods for fabricating Li-ion battery electrodes: (1) material extrusion (ME), which encompasses two subcategories—fused deposition modeling (FDM), also referred to as fused filament fabrication (FFF), and direct ink writing (DIW); (2) material jetting (MJ), including inkjet printing (IJP) and aerosol jet printing (AJP) methods; and (3) vat photopolymerization (VAT-P), which includes the stereolithographic apparatus (SLA) subcategory. These methods have been applied in fabricating substrates, thin-film electrodes, and electrolytes for half-cell and full-cell Li-ion batteries. This discussion focuses on their strengths, limitations, and potential advancements for energy storage applications. [ABSTRACT FROM AUTHOR]

A novel ultra-wideband (UWB) flexible metamaterial absorber (MA) is proposed and thoroughly examined both numerically and experimentally for microwave range applications. The design is based on a rectangular ring array of silver nanoparticles (SNP) inkjet-printed on an ultra-thin flexible Polyethylene terephthalate (PET) substrate. The finite integration technique (FIT) is employed to simulate the proposed design. The results demonstrate absorption performance surpassing 90% across a wide frequency span, ranging from 3 to 96.4 GHz, for both transverse electric (TE) and transverse magnetic (TM) polarizations under normal incidence. The surface current and electric field distributions at different frequencies reveal the underlying physical mechanisms responsible for the UWB absorption phenomenon. Perfect absorption is due to the intrinsic character of the metamaterial structure that can be confirmed from the extracted effective permittivity and effective permeability. The proposed design is fabricated and experimentally tested, demonstrating good agreement with the simulation outcomes. The metamaterial absorber's remarkable characteristics make it highly promising for various applications in communications and stealth, primarily due to its perfect absorptivity over the UWB frequency range. [ABSTRACT FROM AUTHOR]

Recent advancements in artificial intelligence (AI) have highlighted the critical need for energy‐efficient hardware solutions, especially in edge‐computing applications. However, traditional AI approaches are plagued by significant power consumption. In response, researchers have turned to biomimetic strategies, drawing inspiration from the ion‐mediated operating principle of biological synapses, to develop organic neuromorphic devices as promising alternatives. Organic mixed ionic‐electronic conductor (OMIEC) materials have emerged as particularly noteworthy in this field, due to their potential for enhancing neuromorphic computing capabilities. Together with device performance, it is crucial to select devices that allow fabrication via scalable techniques. This study investigates the fabrication of OMIEC‐based neuromorphic devices using inkjet printing, providing a scalable and material‐efficient approach. Employing a commercially available polymer mixed ionic‐electronic conductor (BTEM‐PPV) and a lithium salt, inkjet‐printed devices exhibit performance comparable to those fabricated via traditional spin‐coating methods. These two‐terminal neuromorphic devices demonstrate functionality analogous to literature‐known devices and demonstrate promising frequency‐dependent short‐term plasticity. Furthermore, comparative studies with previous light‐emitting electrochemical cells (LECs) and neuromorphic OMIEC devices validate the efficacy of inkjet printing as a potential fabrication technique. The findings suggest that inkjet printing is suitable for large‐scale production, offering reproducible and stable fabrication processes. By adopting the OMIEC material system, inkjet printing holds the potential for further enhancing device performance and functionality. Overall, this study underscores the viability of inkjet printing as a scalable fabrication method for OMIEC‐based neuromorphic devices, paving the way for advancements in AI hardware. [ABSTRACT FROM AUTHOR]

This paper provides an overview of the types of inks and their formulations for digital printing of wool, silk, cotton, and polyester. The innovative artificial inks were constituted by a fusion of reactive dye, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride and Tween-80 surfactant, five Perylene acid dye inks were synthesised based on Acid red 27, also polyvinyl alcohol and waterborne polyester have been utilised for disperse dye ink formulation. Likewise, sustainable inks were prepared from curcumin and tannic acid incorporating triton x-100 and sodium dodecyl sulfate, additionally dye molecules were encapsulated in a sonicator by an eco-friendly process of mini-emulsion polymerisation with styrene-co-butyl acrylate copolymers. The herbal inks constituted from bio indigo for blue ink, quebracho red for red ink, the flame of the forest for yellow ink and the mixture of three to derive black ink is included herein. Overall, greater colour values, fastness properties and print quality were acquired on the textile substrate inkjet printed with new quebracho red herbal inks. The review offers several novel ink formulations including those that are UV-curable, blue light curing or self-curable inks along with a critical analysis. The pre-treatment requirements, ink formulation, fabric composition, mechanism of printing and the desired end results are interdependent. The paper concludes by highlighting the need for more eco-friendly and simplified ink formulations for digital printing of textile substrates. [ABSTRACT FROM AUTHOR]

Poly(ethylene glycol) diacrylate (PEGDA) is a common polymer in the field of biomedical engineering and can be used for the production of drug delivery systems (DDS). The main advantages of PEGDA are biocompatibility and the ability to alter the physical and chemical properties, thereby ensuring individualized drug release behaviour. The processing of PEGDA via inkjet printing is relevant for the production of DDS. This can be challenging due to the high viscosity of pure PEGDA. In this work, PEGDA, with a molecular weight of 250 g/mol (PEGDA250), was inkjet printed using a Nanoplotter 2.1 with a piezoelectric heatable NanoTip HV-J-H printhead (GeSiM mbH, Radeberg, Germany) at different voltages and temperatures. Droplet generation was analysed in terms of droplet volume and angle deviations. PEGDA250 can be inkjet printed reproducibly in a voltage range of 60 V - 80 V at room temperature (20 °C) or heated up to 38 °C. The average volume of heated (38 °C) PEGDA250 droplets was approximately 110 pl - 150 pl higher than the droplet volume of PEGDA250 in the unheated state. The average angle deviations of main and satellite droplets were mostly < 3°. Increasing voltage or excessive heating of more than 38 °C caused greater instabilities in the droplet generation as well as larger satellite droplets which can affect the accuracy negatively. The studies have shown that PEGDA250 can be processed via inkjet printing and thus can be used as a drug carrier for DDS without the need for mixing with a solvent. [ABSTRACT FROM AUTHOR]

The rise of flexible electronics has sparked a demand for components, such as loudspeakers, that seamlessly integrate into various applications while maintaining their performance. However, current loudspeakers typically rely on electromechanical systems, necessitating significant space for components such as coils and magnets. This limits their flexibility and usage in thin, conformable devices. To address this, a paper‐based thermoacoustic (TA) loudspeaker utilizing carbon nanotubes (CNTs) via inkjet printing is introduced. This TA loudspeaker demonstrates exceptional flexibility and durability, maintaining high acoustic performance across human‐audible frequencies up to 20 kHz, even when subjected to extensive mechanical deformation. Additionally, employing inkjet printing technology streamlines their manufacturing processes, offering a cost‐effective solution with scalability for mass production. Furthermore, an origami‐inspired 3D folding architecture enhances the loudspeaker's portability and enables versatile shape configurations, thus broadening its utility across electronic devices. These demonstrations offer a potential solution for next‐generation audio systems in flexible electronics. [ABSTRACT FROM AUTHOR]

Ultramicrotomy is a well-established technique that has been applied in biology and medical research to produce thin sections or a blockface of an embedded sample for microscopy. Recently, this technique has also been applied in materials science or micro- and nanotechnology as a sample preparation method for subsequent characterization. In this work, an application of ultramicrotomy for the cross-section preparation of an inkjet-printed multilayer structure is demonstrated. The investigated device is a capacitor consisting of three layers. The top and bottom electrodes are printed with silver nanoparticle ink and the dielectric layer with a ceramic nanoparticle/polymer ink. A 3D profilometer is initially used to study the surface morphology of the printed multilayer. The measurements show that both electrodes exhibit a coffee-ring effect, which results in an inhomogeneous layer structure of the device. To obtain precise 3D information on the multilayer, cross-sections must be prepared. Argon ion beam milling is the current gold standard to produce a single cross-section in good quality, however, the cross-section position within the multilayer volume is poorly defined. Moreover, the milling process requires a significant investment of time and resources. Herein, we develop an efficient method to realize repetitive cross-section preparation at well-defined positions in the multilayer volume. Repetitive cross-sections are exposed by trimming with an ultramicrotome (UM) and this blockface is subsequently transferred into a scanning electron microscope (SEM) for imaging. A combination of custom-modified UM and SEM specimen holders allows repeated transfer of the clamped multilayer sample between instruments without damage and with high positioning accuracy. This novel approach enhances the combination of an established ultramicrotome and a SEM for multilayer sample volume investigation. Thus, a comprehensive understanding of printed multilayer structures can be gained, to derive insights for optimization of device architecture and printing process. [ABSTRACT FROM AUTHOR]

Inkjet printing is a promising and scalable drop‐on‐demand deposition technique for cost‐effective mass production of thin film solar cells. However, the efficiency of inkjet‐printed Cu2ZnSn(S,Se)4 (CZTSSe) solar cells based on dimethyl sulfoxide (DMSO) precursor ink is inferior to state‐of‐the‐art spin‐coated devices. Therefore, it is crucial to improve the efficiencies of inkjet‐printed CZTSSe solar cells. In this work, inkjet printing technique is used to deposit flat and continuous CZTSSe thin films in ambient air using a novel 2‐methoxyethanol‐based ink that shows long‐term stability in the air and better wettability compared to the conventional used DMSO‐based ink. In addition, the effects of printing resolution on the structure, morphology, electrical and photovoltaic properties of CZTSSe light harvesting layer are investigated. Eventually, a remarkable device efficiency of 12.86% is achieved, surpassing the reported record efficiency for CZTSSe solar cells based on inkjet printing by ≈40%. Notably, this inkjet printing method allows for the significant reduction of preparation cost of CZTSSe thin films by improving the raw material utilization, thus paving a more viable pathway toward the sustainable development of CZTSSe solar cells. [ABSTRACT FROM AUTHOR]

To meet the ever-increasing demand for anticounterfeiting, developing more information encryption strategies is necessary. Herein, we employed carbon dots (C-Dots), fluorescein isothiocyanate (FITC), and rhodamine 6G (R6G), which emit blue, green, and red fluorescence, to construct an anticounterfeiting encryption system. Structural characterizations showed that carbon dots have very small diameters of only a few nanometers and hydrophilic surface functional groups, which makes them easily and stably dispersed in water. Photophysical studies proved the excitation-wavelength-dependent feature of C-Dots and the existence of binary energy transfer between donor/acceptor pairs (C-Dots/FITC, C-Dots/R6G, and FITC/R6G) in solution and on paper, which can be adjusted by the ratio of fluorophores or the excitation wavelength. The aqueous solutions of R6G/FITC/C-Dots as red/green/blue (RGB) inks to form a ternary energy transfer system were used to fill pens or cartridges for hand-drawing or printing out the multicolored patterns as encrypted anticounterfeiting labels. Under natural or different UV lights, both the hand-drawn patterns on paper and the predesigned patterns printed out on paper/banknote displayed significantly different colors and details, which demonstrated the effectiveness of this anticounterfeiting strategy. Moreover, the information carried by the printed quick response (QR) code could be read under certain specific conditions. No significant change was observed in the printed patterns after 20 verifications or 1 h of continuous UV light irradiation. In all, the multidimensional adjustment in the color/detail of the anticounterfeiting patterns has been realized by combining ternary energy transfer among the three fluorophores with the excitation-wavelength-dependent emission characteristic of C-Dots, and this strategy is promising to be used for practical anticounterfeiting applications. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are important luminescent structures with applications in wide‐color‐gamut displays requiring exceptional color reproducibility. Multinary semiconductor QDs are expected to serve as eco‐friendly materials to replace conventional QDs owing to the narrow spectral widths and tunable bandgaps of these QDs. However, the application of multinary QDs, which tend to exhibit defect‐related emissions, to QD light‐emitting diode (QLED) displays will require electroluminescence to be obtained from QLEDs incorporating inkjet‐printed emitting layers. The present work examines QLEDs exhibiting vibrant color emissions based on blue‐emitting Zn–Se–Te QDs, green‐emitting Ag–In–Ga–S QDs, and red‐emitting Ag–Cu–In–Ga–S QDs. Each such QLED contains QD emitting layers comprising a mixture of charge transport materials. The spectra obtained from these RGB QLEDs fabricated by spin‐coating show very high color purity. Passive matrix QLED displays incorporating these QDs are also fabricated by inkjet printing to demonstrate the high color purity that can be obtained from multinary QDs in displays. In conjunction with passive matrix driving, these displays produce clear moving images with vibrant electroluminescence originating from the multinary QDs. The present results indicate that these QDs have significant potential for utilization in wide‐color‐gamut displays. [ABSTRACT FROM AUTHOR]

Irreversible deformation of paper is a challenge for both printer operation and product quality, particularly in inkjet printing with water-based inks. Here we are investigating permanent paper curl, which is the residual curl of paper after drying of the ink (i.e., it is not the immediate paper curl due to wetting). The key aim of this work was to test the hypothesis that permanent paper curl is created by partial opening and rearrangement of the fibre–fibre bonds in the wetted paper layer. In order to test this hypothesis, we produced paper with crosslinked fibre–fibre bonds that do not open in the presence of water. Polyamideamine epichlorohydrin (PAE) and 1,2,3,4-butanetetracarboxylic acid were used as crosslinking agents and properties of the treated paper samples were analysed. Both agents led to significantly improved wet strength of the papers, furthermore we indeed found that the permanent curl of crosslinked papers was strongly reduced. Other curl related mechanisms like differences in fibre swelling, paper hydroexpansion and liquid penetration were not able to explain the reduction in curl. The finding that the creation of fibre–fibre bonds unaffected by water prevents permanent curl of paper after wetting and redrying leads to the conclusion that the mechanism for creating permanent paper curl after wetting is related to the partial opening and rearrangement of fibre–fibre bonds in the wetted paper. Possible pathways to apply these findings to paper production are discussed, for example switchable or temporary wet strength agents. [ABSTRACT FROM AUTHOR]

The 2D Ti3C2Tx MXene has a large specific surface area, abundant functional groups, and low work function, which has potential in the field of photocatalytic materials. However, the manufacturing of controllable films with high photocatalytic properties and desirable transmittance is a challenging task. Herein, low‐cost, large‐scale, and rapid preparation of Ti3C2Tx/TiO2 flexible composite films have been successfully prepared by inkjet printing technology, which can be applied in complex and special environments, as well as in photoelectrically controllable places for photocatalytic performance. With the increase of the anatase TiO2, the transmittance of Ti3C2Tx/TiO2 films increases from 55.37% to 73.27% at 780 nm, corresponding to the square resistance of 1.112–206.496 kΩ sq−1 and the figure of merit of 0.48–0.005. When the amount of anatase TiO2 is 15%, the film has the best photocatalytic effect on methylene blue (MB) dye, reaching 68.94%. After five cycles of testing, the degradation efficiency of MB dye decreases by only 5.68%, showing that the film has good cycling stability. This work provides a new research direction for photoelectrically controllable photocatalytic degradation in complex and special environments. [ABSTRACT FROM AUTHOR]

Zn anode-based electrochromic devices (ZECDs) stand out as a highly promising technology in the upcoming era of multifunctional electronic devices, offering a blend of electrochromic capabilities and energy storage functions within a single transparent platform. However, significant challenges persist in achieving efficient patterning, ensuring long-term stability, and fast color-switching kinetics for these devices. In this study, heterogeneous tungsten oxide nanowires (W17O47/Na0.1WO3, WNOs) are formulated into inkjet printing ink to assemble patternable ZECDs. The heterogeneous electrode structure of WNO enables a highly capacitive-controlled mechanism that promotes fast electrochromic/electrochemical behavior. Notably, by utilizing a three-dimensional MXene mesh modified substrate, the inkjet-printed ZECDs exhibit a wide optical modulation range of 69.13%, rapid color-changing kinetics (tc = 4.1 s, tb = 5.4 s), and highly reversible capacities of 70 mAh cm-2 over 1000 cycles. This scalable strategy develops the patterned electrodes with a wide optical modulation range and substantial energy storage properties, offering promising prospects for their application in next-generation smart electronics. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs), as emerging electrochemical energy storage devices, have garnered widespread attention due to their rapid charge–discharge characteristics and high power density. With the growing demand for electronic devices and the diversification of applications in daily life scenarios, SCs with outstanding flexibility, mechanical and electrochemical performance are becoming increasingly important. In this study, an in situ reduction method was employed, utilizing inkjet printing technology to deposit reduced graphene oxide (rGO) onto the prepared aramid nanofibrous (ANFs)/PVDF/PVA composite film for the fabrication of solid-state SCs. The optimized ANFs/PVDF/PVA composite film exhibited a tensile strength and Young's modulus of 185 N and 760 MPa, respectively. Even in a bent state, the cyclic voltammetry (CV) curves remained essentially unchanged. At a current density of 0.1 A/g, the specific capacitance and energy density reached 120.9 F/g and 10.8 Wh/kg, respectively, while at a current density of 0.5 A/g, the power density reached 3201 W/kg. After 5000 charge–discharge cycles, the efficiency maintained above 90%. Such exceptional electrochemical and mechanical performance provides more options for the manufacturing of next-generation portable and wearable electronic devices. [ABSTRACT FROM AUTHOR]

Cellular interactions, such as intercellular communication and signal transduction, can be enhanced within three-dimensional cell spheroids, contributing significantly to cellular viability and proliferation. This is crucial for advancements in cancer research, drug testing, and personalized medicine. The dimensions of the cell spheroids play a pivotal role in their functionality, affecting cell proliferation and differentiation, intercellular interactions, gene expression, protein synthesis, drug penetration, and metabolism. Consequently, different spheroid sizes may be required for various drug sensitivity experiments. However, conventional 3D cell spheroid cultures suffer from challenges such as size inconsistency, poor uniformity, and low throughput. To address these issues, we have developed an automated, intelligent system based on inkjet printing. This system allows for precise control of droplet volume by adjusting algorithms, thereby enabling the formation of spheroids of varying sizes. For spheroids of a single size, the printing pattern can be modified to achieve a coefficient of variation within 10% through a bidirectional compensation method. Furthermore, the system is equipped with an automatic pipetting module, which facilitates the high-throughput preparation of cell spheroids. We have implemented a 3 × 3 spheroid array in a 24-well plate, printing a total of 216 spheroids in just 11 min. Last, we attempted to print mouse small intestinal organoids and cultured them for 7 days, followed by immunofluorescent staining experiments. The results indicate that our equipment is capable of supporting the culture of organoids, which is of great significance for high-throughput drug screening and personalized medicine. [ABSTRACT FROM AUTHOR]

Abstract Microneedles are mainly used for pain-free drug administration and in biosensing for wearable systems. They are also promising for fields such as agronomy for precision farming, but their fabrication is not straightforward, often requiring expensive equipment and cleanroom protocols, being unsuitable for mass production. Here, we report a new and simple method for the scalable fabrication of all-inkjet-printed conductive microneedles based on silver nanoparticles (extensible to any other metallic nanoparticle ink) and a simple example of their application for monitoring the electrochemical properties of plants.

Abstract Ultramicrotomy is a well-established technique that has been applied in biology and medical research to produce thin sections or a blockface of an embedded sample for microscopy. Recently, this technique has also been applied in materials science or micro- and nanotechnology as a sample preparation method for subsequent characterization. In this work, an application of ultramicrotomy for the cross-section preparation of an inkjet-printed multilayer structure is demonstrated. The investigated device is a capacitor consisting of three layers. The top and bottom electrodes are printed with silver nanoparticle ink and the dielectric layer with a ceramic nanoparticle/polymer ink. A 3D profilometer is initially used to study the surface morphology of the printed multilayer. The measurements show that both electrodes exhibit a coffee-ring effect, which results in an inhomogeneous layer structure of the device. To obtain precise 3D information on the multilayer, cross-sections must be prepared. Argon ion beam milling is the current gold standard to produce a single cross-section in good quality, however, the cross-section position within the multilayer volume is poorly defined. Moreover, the milling process requires a significant investment of time and resources. Herein, we develop an efficient method to realize repetitive cross-section preparation at well-defined positions in the multilayer volume. Repetitive cross-sections are exposed by trimming with an ultramicrotome (UM) and this blockface is subsequently transferred into a scanning electron microscope (SEM) for imaging. A combination of custom-modified UM and SEM specimen holders allows repeated transfer of the clamped multilayer sample between instruments without damage and with high positioning accuracy. This novel approach enhances the combination of an established ultramicrotome and a SEM for multilayer sample volume investigation. Thus, a comprehensive understanding of printed multilayer structures can be gained, to derive insights for optimization of device architecture and printing process.

In this work, a gate insulator poly (4-vinylphenol) (PVP) of an organic field effect transistor (OFET) was deposited using an inkjet printing technique, realized via a high printing resolution. Various parameters, including the molecular weight of PVP, printing direction, printing voltage, and drop frequency, were investigated to optimize OFET performance. Consequently, PVP with a smaller molecular weight of 11 k and a printing direction parallel to the channel, a printing voltage of 18 V, and a drop frequency of 10 kHz showed the best OFET performance. With a direct ink writing-printed organic semiconductor, this work paves the way for fully inkjet-printed OFETs.

The visualization of the spatial distributions of gases from various sources is essential to understanding the composition, localization, and behavior of these gases. In this study, an inkjet-printed localized surface plasmon resonance (LSPR) subpixel gas sensor array was developed to visualize the spatial distributions of gases and to differentiate between acetic acid, geraniol, pentadecane, and cis-jasmone. The sensor array, which integrates gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), and fluorescent pigments, was positioned 3 cm above the gas source. Hyperspectral imaging was used to capture the LSPR spectra across the sensor array, and these spectra were then used to construct gas information matrices. Principal component analysis (PCA) enabled effective classification of the gases and localization of their sources based on observed spectral differences. Heat maps that visualized the gas concentrations were generated using the mean squared error (MSE) between the sensor responses and reference spectra. The array identified and visualized the four gas sources successfully, thus demonstrating its potential for gas localization and detection applications. The study highlights a straightforward, cost-effective approach to gas sensing and visualization, and in future work, we intend to refine the sensor fabrication process and enhance the detection of complex gas mixtures. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive structural‐color materials have received widespread attention in information encryption due to the significant color changes under different stimuli. However, the trade‐off between the capacity of information input, security level, cost, and large‐area manufacturing greatly limits the application of structural colors in encryption. Herein, dynamic high‐capacity and high‐resolution encryption are achieved by implementing printed total internal reflection (TIR) structural color and computer‐aided image recognition. The printed TIR microstructures are prepared with relative humidity (RH) responsive polymer, which form a heterogeneous wettability system, and can exhibit vibrant color variation with humidity. As the implemented RH is changed, the printed microstructures will expand or shrink precisely, enabling a full‐color modulation across the visible light range. With the color change, each structural‐color pixel can be specifically encoded, allowing for this to encrypt dynamic information within the same pattern at different RHs. Furthermore, This study can precisely integrates tremendous different pixels and easily prepare various encrypted patterns, which guarantee the high‐capacity information input in a low‐cost way. Moreover, through computer programming and algorithm reading, the structural‐color patterns can be decoded and decrypted in real‐time, thus offering great potential for further encryption, anti‐counterfeiting, multiplexing encoding, and data storage. [ABSTRACT FROM AUTHOR]

This study introduces an aluminum transparent heater manufactured with a perforated pattern by using inkjet printing process. The polymeric sacrificial layer was deposited in a periodic dot arrangement by inkjet printing and a aluminum thin film was deposited using a vacuum deposition process. By the ultrasonic punching to remove inkjet‐printed sacrificial layer, the transparent electrode with perforated metal pattern was formed. From the multiphysics simulation, it is investigated that the narrow region of the perforated pattern is efficient to generate Joule heating. The relationship between electrical and thermal properties is investigated by adjusting the spacing of holes in the aluminum grid. Finally, the performance of the fabricated transparent heater is demonstrated that ice cube placed on top of the manufactured transparent heater is removed within 120 s. This ultrasonic punching with inkjet‐printed sacrificial layer is expected to be applicable to various applications. [ABSTRACT FROM AUTHOR]

Integration of lead‐halide perovskite quantum dots (PQDs) into full‐color microarrays presents numerous advantages for full‐color micro‐LED displays. There is an urgent requirement for a new design approach that simplifies the creation of durable PQD/polymer composites to produce stable PQD microarrays. Here, mono‐2‐(methacryloyloxy)ethyl succinate (MMeS) is utilized as a functional ligand to synthesize green MMeS‐modified CsPbBr3 PQDs (M‐CPB PQDs). The subsequent photopolymerization of M‐CPB PQDs with 1,6‐hexanediol diacrylate (HDDA) forms a CsPbBr3 PQD/polymer composite. This composite exhibits a solid‐state photoluminescence quantum yield of 73.1%, and the photoluminescence intensity retains 72% of its original value after 17 days of continuous immersion in water. Stable green PQD/polymer microarrays can be printed using an ink containing M‐CPB PQDs, HDDA, diphenyl (2,4,6‐trimethylbenzoyl) phosphine oxide, and n‐dodecane via electrohydrodynamic jet printing and in situ polymerization under UV light irradiation. Full‐color patterns can also be generated with MMeS‐modified red, green, and blue PQDs. These findings highlight the critical role of functionalizing the surface ligands of PQDs to improve their processability, thereby facilitating the development of stable PQD/polymer microarrays. [ABSTRACT FROM AUTHOR]

Dielectric elastomers (DEs), have attracted interest because they can replicate the behavior of muscles. They can change shape when subjected to an electric field. A novel DE is proposed in this study that incorporates silicon carbide (SiC) nanowires into silicone rubber (SR). The nanowires were propagated using polycarbosilane via a chemical vapor reaction (CVR). A boronate polymer was employed to promote compatibility between SR and SiC nanowires which modified the nanowire surfaces, leveraging a strong adhesive quality of the catechol moiety. Electrohydrodynamic (EHD) inkjet printing was then used to form the DEs into various shapes. These DEs had substantial dielectric constants of the order of 4.46. Significantly, one of the DEs achieved the highest actuated area strain of 20.36% in an electric field of 16.5 V/μm, demonstrating excellent driving performance. Furthermore, when used the fabricated DEs showed pronounced long‐term stability, meaning they are capable of finding applications in artificial intelligence, biomimetics, aerospace, and other disciplines. Highlights: The SiC nanowires were obtained through a chemical vapor reaction.A boronate polymer with catechol moiety was used to modify the SiC nanowires.DEs were formed various shapes by inkjet printing.DEs achieved very large actuated strains of up to 20.36% at 16.5 V/μm. [ABSTRACT FROM AUTHOR]

Interaction between tumor‐associated macrophages and tumor cells is crucial for tumor development, metastasis, and the related immune process. However, the macrophages are highly heterogeneous spanning from anti‐tumorigenic to pro‐tumorigenic, which needs to be understood at the single‐cell level. Herein, a sessile microdroplet system designed for monitoring cellular behavior and analyzing intercellular interaction, demonstrated with macrophage‐tumor cell pairs is presented. An automatic procedure based on the inkjet printing method is utilized for the precise pairing and co‐encapsulation of heterotypic cells within picoliter droplets. The sessile nature of microdroplets ensures controlled fusion and provides stable environments conducive to adherent cell culture. The nitric oxide generation and morphological changes over incubation are explored to reveal the complicated interactions from a single‐cell perspective. The immune response of macrophages under distinct cellular microenvironments is recorded. The results demonstrate that the tumor microenvironment displays a modulating role in polarizing macrophages from anti‐tumorigenic into pro‐tumorigenic phenotype. The approach provides a versatile and compatible platform to investigate intercellular interaction at the single‐cell level, showing promising potential for advancing single‐cell behavior studies. [ABSTRACT FROM AUTHOR]

Printed electronics have made remarkable progress in recent years and inkjet printing (IJP) has emerged as one of the leading methods for fabricating printed electronic devices. However, challenges such as nozzle clogging, and strict ink formulation constraints have limited their widespread use. To address this issue, a novel nozzle‐free printing technology is explored, which is enabled by laser‐generated focused ultrasound, as a potential alternative printing modality called Shock‐wave Jet Printing (SJP). Specifically, the performance of SJP‐printed and IJP‐printed bottom‐gated carbon nanotube (CNT) thin film transistors (TFTs) is compared. While IJP required ten print passes to achieve fully functional devices with channel dimensions ranging from tens to hundreds of micrometers, SJP achieved comparable performance with just a single pass. For optimized devices, SJP demonstrated six times higher maximum mobility than IJP‐printed devices. Furthermore, the advantages of nozzle‐free printing are evident, as SJP successfully printed stored and unsonicated inks, delivering moderate electrical performance, whereas IJP suffered from nozzle clogging due to CNT agglomeration. Moreover, SJP can print significantly longer CNTs, spanning the entire range of tube lengths of commercially available CNT ink. The findings from this study contribute to the advancement of nanomaterial printing, ink formulation, and the development of cost‐effective printable electronics. [ABSTRACT FROM AUTHOR]

In this work, a novel MEMS-compatible energetic film consisting of 3,4-bis(3-nitrofurazan-4-yl)furoxan(DNTF)/ polydimethylsiloxane(PDMS)-ethyl cellulose (EC) was prepared on an aluminum substrate by inkjet printing. The dense layered energetic film was prepared by stepwise layer-by-layer deposition and thermal curing, its maximum elastic modulus reached 9.865 GPa in the nanoindentation test, and the strong adhesion between the energetic film and the substrate was confirmed by drop experiments. Most importantly, the critical detonation thickness of the energetic film is 0.15 mm in a 1 mm width wedge-shaped groove. [ABSTRACT FROM AUTHOR]

Anode-free lithium batteries (AFLBs) present an opportunity to eliminate the need for conventional graphite electrodes or excess lithium–metal anodes, thus increasing the cell energy density and streamlining the manufacturing process. However, their attributed poor coulombic efficiency leads to rapid capacity decay, underscoring the importance of achieving stable plating and stripping of Li on the negative electrode for the success of this cell configuration. A promising approach is the utilization of lithiophilic coatings such as silver to mitigate the Li nucleation overpotential on the Cu current collector, thereby improving the process of Li plating/stripping. On the other hand, inkjet printing (IJP) emerges as a promising technique for electrode modification in the manufacturing process of lithium batteries, offering a fast and scalable technology capable of depositing both thin films and patterned structures. In this work, a Fujifilm Dimatix inkjet printer was used to deposit Ag sites on a Cu current collector, aiming to modulate the interfacial electrochemistry of the system. Samples were fabricated with varying areas of coverage and the electrochemical performance of the system was systematically evaluated from bare Cu (non-lithiophilic) to a designed pattern (partially lithiophilic) and the fully coated thin film case (lithiophilic). Increasing lithiophilicity resulted in lower charge transfer resistance, higher exchange current density and reduced Li nucleation overpotential (from 55.75 mV for bare Cu to 13.5 mV for the fully coated case). Enhanced half-cell cyclability and higher coulombic efficiency were also achieved (91.22% CE over 76 cycles for bare Cu, 97.01% CE over 250 cycles for the fully coated case), alongside more uniform lithium deposition and fewer macroscopic irregularities. Moreover, our observations demonstrated that surface patterning through inkjet printing could represent an innovative, easy and scalable strategy to provide preferential Li nucleation sites to guide the subsequent Li deposition. [ABSTRACT FROM AUTHOR]

[Objective] The preparation of luminescent display pixels using inkjet printing technology offers significant advantages, including low cost, flexibility, and the potential for large-scale production. This approach effectively reduces the production cost of OLED displays. The process of inkjet printing organic light-emitting layers is particularly crucial and complex. It requires designing and optimizing driving waveforms to achieve stable droplet formation without satellite points. Additionally, the printing line width and thickness must be adjusted to produce a dense and uniform thin film. Before preparing display pixels, it is essential to observe the inkjet droplets and assess their stability. However, changes in driving waveform parameters, ink ratio, or printing temperature can affect various parameters, including ink droplet uniformity, stability, volume, and injection speed--changes that are often undetectable by the naked eye. [Methods] This study investigates an automatic measurement technology for inkjet droplet parameters. A droplet-driving waveform customization module has been integrated into LabVIEW software using the NI Vision visual development module. This optimization of the droplet-driving waveform aims to achieve perfect jet droplets. The droplet image is captured using phase delay technology, which employs two control signals of the same frequency and a constant phase difference. One signal is the droplet drive signal, while the other is a square wave signal that triggers the camera and strobe light source. When the first driving waveform from the nozzle arrives, another signal is output as a pulse square wave after a delay of Δt. At this moment, the strobe light source activates, and the camera captures an image of the ink droplet. When the nozzle continuously sprays ink droplets at a fixed frequency, Δt remains constant, resulting in multiple images captured by the camera that maintain consistency, giving the appearance that the ink droplets are stationary in the air. By varying the delay time Δt between the two signals, the position of the ink droplets changes, allowing for the simulation of the dynamic falling process of the ink droplets. [Results] Droplet images are obtained at different times with a phase delay of Δt = 10 µs, capturing a complete spraying process. The images undergo filter denoising, binary conversion, morphological operations, and edge detection to obtain clear droplet contours. The volume of the ink droplets is calculated using an integral formula, and the diameter of the droplets is further determined using the spherical volume formula. The spray speed of the droplets is calculated based on the differences in ink droplet positions across multiple frames of images. [Conclusions] This research on automatic measurement technology for inkjet droplet parameters has resulted in the development of a hardware device for droplet observation, with a software control system implemented in LabVIEW graphical programming language. Droplet images are captured at different times with a phase delay of Δt=10 µs. Each image undergoes filtering, denoising, binary conversion, morphological operations, and edge detection to obtain clear droplet contours, thereby capturing a complete spraying process. The effective extraction of droplet contours, along with the automatic calculation of droplet spraying speed, diameter, and volume parameters, provides a visualization tool for optimizing ink preparation and inkjet printing, thereby facilitating the production of high-quality films. [ABSTRACT FROM AUTHOR]