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We demonstrate the direct printing of silver nano- and microstructures via two-photon absorption. The samples show very low porosity, high conductance and optical quality surfaces. These structures might find their application in plasmonics and antenna applications.

3D printing has enabled materials, geometries and functional properties to be combined in unique ways otherwise unattainable via traditional manufacturing techniques, yet its adoption as a mainstream manufacturing platform for functional objects is hindered by the physical challenges in printing multiple materials. Vat polymerization offers a polymer chemistry-based approach to generating smart objects, in which phase separation is used to control the spatial positioning of materials and thus at once, achieve desirable morphological and functional properties of final 3D printed objects. This study demonstrates how the spatial distribution of different material phases can be modulated by controlling the kinetics of gelation, cross-linking density and material diffusivity through the judicious selection of photoresin components. A continuum of morphologies, ranging from functional coatings, gradients and composites are generated, enabling the fabrication of 3D piezoresistive sensors, 5G antennas and antimicrobial objects and thus illustrating a promising way forward in the integration of dissimilar materials in 3D printing of smart or functional parts., 3D printing has enabled materials, geometries and functional properties to be combined in unique ways but printing multiple materials remains challenging. Here, the authors demonstrate how spatial distribution of different material phases can be modulated by controlling the kinetics of gelation, cross-linking density and material diffusivity in vat polymerization.

Prednisolone is a steroid class drug that is used to treat certain types of allergies, inflammatory conditions, autoimmune disorders and cancer. Solubility of prednisolone is very difficult to dissolve in water causing problems in the absorption process so that the optimum formula is needed to form Prednisolone tablets that meet the requirements of the physical properties of tablets. The purpose of this study was to make the optimum formula with a combination of lactose excipients, avicel pH-101, and amprotab to obtain prednisolone tablets with good physical properties and dissolution. Prednisolone tablets made 7 formulas with a combination of lactose (A) Avicel PH-101 (B), and Amprotab (C), Formula I (100% A); Formula II (100% B); Formula III (100% C); Formula IV (50% A + 50% B); Formula V (50% A + 50% C); Formula VI (50% B + 50% C); Formula VII (33.33% A + 33.33% B + 33.33% C) in 2 batches. The method of making prednisolone tablets by direct printing. Testing of prednisolone tablets included the physical properties of tablets, weight uniformity, uniformity in size, hardness, friability, disintegration time, and dissolution test, and content determination. Keywords: optimization of formulas, tablets, Prednisolone, Simplex Lattice Design.

In recent years, surface patterning of membranes has been explored as a new strategy to modify surface properties of polymeric membranes. A variety of methods including template-based micromolding and direct printing have been developed for effective fabrication of surface-patterned membranes. In this review, we compare the underlying pattern replication mechanisms and the advantages and challenges associated with the range of different fabrication methods. The presence of the surface patterns, when properly created, can enlarge the active surface/interfacial area, create more effective conduction pathways, and enhance the hydrodynamic effects. These effects can be harnessed for improving membrane performance for a wide range of applications.

Transparent platinum electrodes are prepared using nanoimprint lithography of a newly developed molecular platinum complex. Thermal decomposition at moderate temperature of this complex gives rise to elemental platinum line and grid pattern with linewidths down to 40 nm. These electrodes exhibit transmittances of 90% and resistances below 100 Ω. Thus, for the first time, highly transparent electrodes are prepared by a direct soft lithographical printing process.

Vascularization is one major obstacle in bioprinting and tissue engineering. In order to create thick tissues or organs that can function like original body parts, the presence of a perfusable vascular system is essential. However, it is challenging to bioprint a hydrogel-based three-dimensional vasculature-like structure in a single step. In this paper, we report a new hydrogel-based composite that offers impressive printability, shape integrity, and biocompatibility for 3D bioprinting of a perfusable complex vasculature-like structure. The hydrogel composite can be used on a non-liquid platform and is printable at human body temperature. Moreover, the hydrogel composite supports both cell proliferation and cell differentiation. Our results represent a potentially new vascularization strategy for 3D bioprinting and tissue engineering. NRF (Natl Research Foundation, S’pore) Published version

Three dimensional (3D) bioprinting technology enables the freeform fabrication of complex constructs from various hydrogels and is receiving increasing attention in tissue engineering. The objective of this study is to develop a novel self-supporting direct hydrogel printing approach to extrude complex 3D hydrogel composite structures in air without the help of a support bath. Laponite, a member of the smectite mineral family, is investigated to serve as an internal scaffold material for the direct printing of hydrogel composite structures in air. In the proposed printing approach, due to its yield-stress property, Laponite nanoclay can be easily extruded through a nozzle as a liquid and self-supported after extrusion as a solid. Its unique crystal structure with positive and negative charges enables it to be mixed with many chemically and physically cross-linked hydrogels, which makes it an ideal internal scaffold material for the fabrication of various hydrogel structures. By mixing Laponite nanoclay with various hydrogel precursors, the hydrogel composites retain their self-supporting capacity and can be printed into 3D structures directly in air and retain their shapes before cross-linking. Then, the whole structures are solidified in situ by applying suitable cross-linking stimuli. The addition of Laponite nanoclay can effectively improve the mechanical and biological properties of hydrogel composites. Specifically, the addition of Laponite nanoclay results in a significant increase in the Young's modulus of each hydrogel-Laponite composite: 1.9-fold increase for the poly(ethylene glycol) diacrylate (PEGDA)-Laponite composite, 7.4-fold increase for the alginate-Laponite composite, and 3.3-fold increase for the gelatin-Laponite composite.

In this paper, a high-resolution direct printing process was developed for molten metal using Electrohydrodynamic (EHD) printing technology. The effect of the critical printing conditions, such as voltage and printing speed, on the printing process was characterized. Compared with direct extrusion using pneumatic pressure, the EHD printing can effectively reduce the dimension of the printed filament down to less than 50 μm with better quality of the printed features. We successfully applied EHD printing to print high-resolution 2D patterns and some high aspect-to-ratio 3D structures, which demonstrated the potential capabilities of EHD printing process in producing fine metal structures.

Additive manufacturing has revolutionized the building of materials direct from design, allowing high resolution rapid prototyping in complex 3D designs with many materials. 3D printing hasenabled high strength damage-tolerant structures, bioprinted artificial organs and tissues, ultralight metals, medicine, education, prosthetics, architecture, consumer electronics,and as a prototyping tool for engineers and hobbyists alike. 3D printing has emerged as a useful tool for complex electrode and material assembly method for batteries and supercapacitors in recent years. The field initially grew from extrusion-based methods such as fused deposition modelling, and evolved to photopolymerization printing of intricate composites, while supercapacitor technologies less sensitive to solvents more often involved material jetting processes. Underpinning every part of a 3D printable battery and many other devices is the printing method and the nature of the feed material. Material purity, printing fidelity, accuracy, complexity, and the ability to form conductive, ceramic, glassy, or solvent-stable plastics relies on the nature of the feed material or composite to such an extent, that the future of 3D printable batteries and electrochemical energy storage devices will depend on materials and printing methods that are co-operatively informed by the requirements of the device and how it is fabricated. In this Perspective, we address the materials and methods requirements in 3D printable batteries and supercapacitors and outline requirements for the future of the field by linking existing performance limitations to the requirements of printable energy storage materials, casing materials and the direct printing of electrodes and electrolytes. We also look to the future by taking inspiration from additive manufacturing, to posit links between materials and printing methods to allow new form factor cells., Comment: 50 pages, 9 figures, 204 references

Direct printing of waveguide and flow-channel on Nanoporous-network in SiO2 layer was proposed and studied. Non spherical nano-SiO2 was coated as transparent platform, and nano-spherical polymer was permeated into the layer to draw waveguide.

Pyro-electrohydrodynamic jet printing (p-jet) has been used to fabricate a nanostructured plasmonic sensor for SERS spectroscopy. The p-jet approach allowed us to have an assembly of nanoparticles with suitable geometry and size, which resulted in a sensing surface with intense SERS activity and a rather homogeneous response. Raman imaging measurements highlighted strong Enhancement Factors across the sensing area, exceeding those of the pristine colloidal solution by almost two orders of magnitude. The intense plasmonic effect was further demonstrated by the spectroscopic recognition of a metal-catalyzed dimerization process triggered to completeness at the metal surface. The results presented herein demonstrate the usefulness of the proposed SERS sensor for hypersensitive molecular analysis.

Layered Manufacturing enabled the direct production of sand molds and cores by selective injection of binding agents into sand layer. These binding agents are chemically reactive and have significantly higher cost in comparison to Bentonite clay used in routine foundry work. These binders also need special mechanism for printing and storage which result into increased equipment cost. The present study explores feasibility of using low-cost natural binding agent, orange peel powder as an alternative to chemical binders. A preliminary framework for layered manufacturing of standard sand testing samples employing natural binders is developed. Some of the important mold properties such as mold hardness, mold permeability and green compressive and shear strength are evaluated. The results are compared with standard sand testing specimen prepared using conventional binding agents. It has been observed that the mold hardness and strength properties of layered mold using orange peel powder are significantly better. The outcomes of this preliminary study are quite encouraging and further work will focus on investigating reasons for improved sand mold properties and development of low cost layered manufacturing equipment for direct printing of sand molds.

Bioprinting techniques can be used for the in vitro fabrication of functional complex bio-structures. Thus, extensive research is being carried on the use of various techniques for the development of 3D cellular structures. This article focuses on direct writing techniques commonly used for the fabrication of cell structures. Three different types of bioprinting techniques are depicted: Laser-based bioprinting, ink-jet bioprinting and extrusion bioprinting. Further on, a special reference is made to the use of the bioprinting techniques for the fabrication of 2D and 3D liver model structures and liver on chip platforms. The field of liver tissue engineering has been rapidly developed, and a wide range of materials can be used for building novel functional liver structures. The focus on liver is due to its importance as one of the most critical organs on which to test new pharmaceuticals, as it is involved in many metabolic and detoxification processes, and the toxicity of the liver is often the cause of drug rejection.

Application of the paste containing the dyes to the required areas on the fabrics is designated as direct printing, consequently dyeing and steaming followed by washing to remove any residues. In pigment printing, the pigments and cured binder adhere to fabric surface with the cured binder film. No further treatment is required. Direct printing is considered the most important printing. Fibers have been defined by the textile institute as units of matter which are characterized by fineness flexibility and high ratio of length to thickness. Fibers are the basic unit from which all textile materials are made. Textile goods are manufactured from fibrous material which may be either of natural or man-made origin.

Recent advances in perovskite solar cells (PSCs) have resulted in greater than 23% efficiency with superior advantages such as flexibility and solution-processability, allowing PSCs to be fabricated by a high-throughput and low-cost roll-to-roll (R2R) process. The development of scalable deposition processes is crucial to realize R2R production of flexible PSCs. Gravure printing is a promising candidate with the benefit of direct printing of the desired layer with arbitrary shape and size by using the R2R process. Here, flexible PSCs are fabricated by gravure printing. Printing inks and processing parameters are optimized to obtain smooth and uniform films. SnO2 nanoparticles are uniformly printed by reducing surface tension. Perovskite layers are successfully formed by optimizing the printing parameters and subsequent antisolvent bathing. 2,2′,7,7′-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene is also successfully printed. The all-gravure-printed device exhibits 17.2% champion efficiency, with 15.5% maximum power point tracking efficiency for 1000 s. Gravure-printed flexible PSCs based on a two-step deposition of perovskite layer are also demonstrated. Furthermore, a R2R process based on the gravure printing is demonstrated. The champion efficiency of 9.7% is achieved for partly R2R-processed PSCs based on a two-step fabrication of the perovskite layer.

Microfluidic paper-based analytical devices (µPADs) have gained a lot of attention in recent years because they enable the production of diagnostic devices in a simple and cost-efficient way. To control the fluidic flow, hydrophobic barriers are generated that reach into the fibrous structure of the paper. Popular methods for creating such barriers are wax printing or polymer deposition. These barriers are however very stiff: bending or folding leads to the destruction of the barriers. Another problem is the low resistance of common barrier materials against different solvents, which makes it impossible to execute chemical tests on paper. Destruction of the barriers leads to leakage and causes assay failure. Here we present a method that produces bendable hydrophobic barriers on paper by photolithography. These barriers are based on silanes and withstand solvents such as DMSO. We show that these barriers can also be autoclaved, which is important for conducting biological assays using bacteria or cells on μPADs.

In this paper a novel approach is presented for the monitoring of sitting posture. This work addresses the application context of assistive technology for the elderly, as part of a PC Interreg Italy-Malta project, called NATIFLife. The system developed consists in a flexible sensor matrix realized by low-cost inkjet printing. Main advantages of the solution proposed are related to the adopted direct printing technology, which allows for the rapid prototyping of customized solution shaped as a function of users and/or the application context. The idea behind the application, its implementation and the first experimental results on sensor characterization are presented.

In this study, a high-performance photoanode based on 3D periodic, micropillar-structured fluorine-doped tin oxide (FTO-MP) deposited with BiVO4 is fabricated using the patterned FTO by direct printing and spray pyrolysis, followed by the deposition of BiVO4 by sputtering and V ion heat-treatment on the patterned FTO. The FTO-MP enables light scattering owing to its 3D periodic structure and increases the light absorption efficiency. In addition, the high electron mobility of FTO and enlarged surface area of FTO-MP enhance the separation efficiency. Due to the combination of these enhancing strategies, the photocurrent density of micropillar-patterned BiVO4 at 1.23 VRHE reached 2.97 mA cm-2 , which is 67.8% higher than that of flat BiVO4 . The results suggest that the efficiency can increase significantly using the patterned FTO fabricated by an inexpensive and simple process (i.e., direct printing and spray pyrolysis), thereby indicating a new strategy for the enhancement of efficiency in various energy fields.

A direct printing of liquid droplet matrix on various surfaces is demonstrated using a stamp that can be recycled for over 100 times. The technique can be applied to pattern functional organic materials and nanoparticles and fabricate microlens arrays in one step. By controlling the printing pressure and the surface wettability, a feature size that is smaller than that of the stamp was achieved in a tunable manner.

A newly developed nanoparticle printer is presented for high resolution pattering of conductive nanoparticles onto the carbon and glass fiber reinforced composites. The nanoparticles are aerodynamically focused to generate nanoparticle beam for high resolution patterns. The resulting conductive patterns are evaluated for the strain measurement of composites for structural health monitoring (SHM). A series of strain sensors are printed onto the composites and their performances are characterized in terms of gauge factor, measurable range, and etc. The presented work leverages the advanced techniques of process and part monitoring of composite manufacturing as well as for the SHM of the composite.

This letter proposes an electrohydrodynamics-based printing system developed with high-precision on-off control, which has the merits of anticlog printing, maskless patterning, and precise control. Silver-colloid-based precursor can be conveniently focused into a single and continuous liquid jet and directly printed on glass or aluminum foil substrates just like a dip-pen. The liquid jet itself can be as thin as a couple of microns, and the minimum silver linewidth could reach 30 μm. With high-precision on-off control of the spraying, complex pictures, letters, as well as a specially designed radio frequency identification (RFID) tag antenna were printed using this system. The printed RFID tag antenna was characterized and analyzed, which meets the basic requirements of practical applications.

Control of film's properties is the most important for providing of customized electronic devices. In particular, when the nanocomposite networks are applied to the films for needs of various applications, the quality of film is considered as one of the most potent factors. Here, we propose a viable and facile method of controlling the silver nanowire (Ag NW)-elastomer nanocomposite networks through elaborate direct printing for implementing sandwich-structured ultrathin and stretchable strain sensors. According to the different Ag NW network densities controlled by various blade coating parameters, surface morphological characteristics, optical transmittance, and current–voltage performance were investigated. In order to exhibit the importance of network density control to electronic devices, we fabricated two stretchable strain sensors with different sensitivities (ΔR/R0: 6.31, 0.70 at 10% strain) using low density (LD) and high density (HD) Ag NWs networks for detecting small and large movements, respectively. Under repeated stretching fatigue tests (1000 cycles), LD and HD Ag NW sensors show stable sensing operation with electromechanical durability and frequency-responsive features. A simple application for wrist motion detection with a fast response speed and stable operation is demonstrated. These results provide a new route towards next-generation skin electronics.

In this study, a liquid metal is directly printed on various types of surfaces using an automated dispensing system. A particular class of liquid metals called eutectic gallium–indium (Ga: 75.5% In: 24.5% by weight ratio) was chosen and printed on flat, inclined (20°, 30°, 40°, and 50°), and curved ( = 0.02, 0.03, 0.04, and 0.05 mm−1) surfaces. The inner diameter of the dispenser nozzle, the distance between the nozzle tip and the surface of the substrate, turned out to be the crucial parameters that determine the performance of printing, based on the experimental evaluation of the relationship between the trace width and the parameters. We were able to control the trace width under 200 m as small as 22 m by adjusting the parameters we tested. To the best of our knowledge, an EGaIn trace 22 m in width is the smallest one achieved by direct printing of a liquid metal on three-dimensional (3D) surfaces. Also, we were able to print not only straight lines but also curved patterns, such as spiral shapes. This will lead to the miniaturization of stretchable electronics with any pattern shapes consisting of straight lines and curves. As an example of applications of the proposed method, a micro-scale pressure sensor with a spiral trace pattern was fabricated, and its performance was evaluated with loading and unloading tests. Another application of the proposed method includes direct printing of stretchable electronics on surfaces with arbitrary shapes and curvatures. It was demonstrated with a seven-segment display circuit and soft sensors printed on a mannequin hand. We believe the proposed method and its applications will open a new space in development of soft electronics and robots.

High-resolution, 3D reconfiguration method using liquid metals is studied for stretchable 3D integrations in electronics., We report an unconventional approach for high-resolution, reconfigurable 3D printing using liquid metals for stretchable, 3D integrations. A minimum line width of 1.9 μm can be reliably formed using direct printing, and printed patterns can be reconfigured into diverse 3D structures with maintaining pristine resolutions. This reconfiguration can be performed multiple times, and it also generates a thin oxide interface that can be effective in preventing the spontaneous penetration of gallium atoms into different metal layers while preserving electrical properties under ambient conditions. Moreover, these free-standing features can be encapsulated with stretchable, conformal passivations. We demonstrate applications in the form of a reconfigurable antenna, which is tunable by changing geometeries, and reversibly movable interconnections used as mechanical switches. The free-standing 3D structure of electrodes is also advantageous for minimizing the number and space between interconnections, which is important for achieving higher integrations, as demonstrated in an array of microLEDs.

The field of tissue engineering has produced new therapies for the repair of damaged tissues and organs, utilizing biomimetic scaffolds that mirror the mechanical and biological properties of host tissue. The emergence of three-dimensional printing (3DP) technologies has enabled the fabrication of highly complex scaffolds which offer a more accurate replication of native tissue properties and architecture than previously possible. Of strong interest to tissue engineers is the construction of multilayered scaffolds that target distinct regions of complex tissues. Musculoskeletal and dental tissues in particular, such as the osteochondral unit and periodontal complex, are composed of multiple interfacing tissue types, and thus benefit from the usage of multilayered scaffold fabrication. Traditional 3DP technologies such as extrusion printing and selective laser sintering have been used for the construction of scaffolds with gradient architectures and mixed material compositions. Additionally, emerging bioprinting strategies have been used for the direct printing and spatial patterning of cells and chemical factors, capturing the complex organization found in the body. To better replicate the varied and gradated properties of larger tissues, researchers have created scaffolds composed of multiple materials spanning natural polymers, synthetic polymers, and ceramics. By utilizing high precision 3DP techniques and judicious material selection, scaffolds can thus be designed to address the regeneration of previously challenging musculoskeletal, dental, and other heterogeneous target tissues. These multilayered 3DP strategies show great promise in the future of tissue engineering.

Background: Three-dimensional printing (3DP) is a novel technology for fabrication of personalized medicine. As of late, FDA affirmed 3D printed tranquilize item in August 2015, which is characteristic of another section of Pharmaceutical assembling. 3DP incorporates a wide range of assembling procedures, which are altogether founded on computer-aided design (CAD), and controlled deposition of materials (layer-by-layer) to make freestyle geometries. Conventionally, many pharmaceutical processes like compressed tablet have been used from many years for the development of tablet with established regulatory pathways. But this simple process is outdated in terms of process competence and manufacturing flexibility (design space). 3DP is a new technology for the creation of plan, proving to be superior for complex products, customized items and items made on-request. It creates new opportunities for improving efficacy, safety, and convenience of medicines. Method: There are many of the 3D printing technology used for the development of personalized medicine on demand for better treatment like 3D powder direct printing technology, fused-filament 3D printing, 3D extrusion printer, piezoelectric inkjet printer, fused deposition 3D printing, 3D printer, ink-jet printer, micro-drop inkjet 3DP, thermal inkjet printer, multi-nozzle 3D printer, stereolithographic 3D printer. Result: This review highlights features how item and process comprehension can encourage the improvement of a control technique for various 3D printing strategies. Conclusion: It is concluded that the 3D printing technology is a novel potential for manufacturing of personalized dose medicines, due to better patient compliance which can be prepared when needed.

Direct printing technique has become indispensable in flexible electronics and low cost sensor applications. It has transformed into an enabling technology for many flexible devices. However, it is not very well explored for printing optical materials. In this work, a micro-dispense printer for printing polymeric optical waveguides was custom-built. It was employed to develop a simple method to couple light into printed optical interconnects. It was also used to apply a voltage bias during printing and drying of electro-optic polymer (SEO110) to pole the SEO110 in-situ with the goal of eliminating the need for traditional high temperature contact poling. With this in-situ poling method, electro-optic effect in SEO110 was demonstrated.

Three-dimensional (3D) printing represents the direct fabrication of parts layer-by-layer, guided by digital information from a computer-aided design file without any part-specific tooling. Over the past three decades, a variety of 3D printing technologies have evolved that have transformed the idea of direct printing of parts for numerous applications. Three-dimensional printing technology offers significant advantages for biomedical devices and tissue engineering due to its ability to manufacture low-volume or one-of-a-kind parts on-demand based on patient-specific needs, at no additional cost for different designs that can vary from patient to patient, while also offering flexibility in the starting materials. However, many concerns remain for widespread applications of 3D-printed biomaterials, including regulatory issues, a sterile environment for part fabrication, and the achievement of target material properties with the desired architecture. This article offers a broad overview of the field of 3D-printed biomaterials along with a few specific applications to assist the reader in obtaining an understanding of the current state of the art and to encourage future scientific and technical contributions toward expanding the frontiers of 3D-printed biomaterials.

Biohybrids can be defined as the functional combination of proteins, viable cells or microorganisms with non-biological materials. This article reviews recent findings on the encapsulation of microorganisms and eukaryotic cells in inorganic matrices such as silica gels or cements. The entrapment of biological entities into a support material is of great benefit for processing since the encapsulation matrix protects sensitive cells from shear forces, unfavourable pH changes, or cytotoxic solvents, avoids culture-washout, and simplifies the separation of formed products. After reflecting general aspects of such an immobilization as well as the chemistry of the inorganic matrices, we focused on manufacturing aspects and the application of such biohybrids in biotechnology, medicine as well as in environmental science and for civil engineering purpose. Statement of significance The encapsulation of living cells and microorganisms became an intensively studied and rapidly expanding research field with manifold applications in medicine, bio- and environmental technology, or civil engineering. Here, the use of silica or cements as encapsulation matrices have the advantage of a higher chemical and mechanical resistance towards harsh environmental conditions during processing compared to their polymeric counterparts. In this perspective, the article gives an overview about the inorganic material systems used for cell encapsulation, followed by reviewing the most important applications. The future may lay in a combination of the currently achieved biohybrid systems with additive manufacturing techniques. In a longer perspective, this would enable the direct printing of cell loaded bioreactor components.