On-demand Printing Research Articles

3D printing for drug manufacturing: A perspective on the future of pharmaceuticals

Since a three-dimensional (3D) printed drug was first approved by the Food and Drug Administration in 2015, there has been a growing interest in 3D printing for drug manufacturing. There are multiple 3D printing methods – including selective laser sintering, binder deposition, stereolithography, inkjet printing, extrusion-based printing, and fused deposition modeling – which are compatible with printing drug products, in addition to both polymer filaments and hydrogels as materials for drug carriers. We see the adaptability of 3D printing as a revolutionary force in the pharmaceutical industry. Release characteristics of drugs may be controlled by complex 3D printed geometries and architectures. Precise and unique doses can be engineered and fabricated via 3D printing according to individual prescriptions. On-demand printing of drug products can be implemented for drugs with limited shelf life or for patient-specific medications, offering an alternative to traditional compounding pharmacies. For these reasons, 3D printing for drug manufacturing is the future of pharmaceuticals, making personalized medicine possible while also transforming pharmacies.

Predictive Three-Dimensional Printing of Spare Parts with Internet of Things

Industry 4.0 integrates digital and physical technologies to transform work management, where two core enablers are the internet of things (IoT) and three-dimensional printing (3DP). IoT monitors complex systems in real time, whereas 3DP enables agile manufacturing that can respond to real-time information. However, the details of how these two can be integrated are not yet clear. To gain insights, we consider a scenario where a three-dimensional (3D) printer supplies a critical part to multiple machines that are embedded with sensors and connected through IoT. Although the public perception indicates that this integration would enable on-demand printing, our research suggests that this is not necessarily the case. Instead, the true benefit is the ability to print predictively. In particular, it is typically more effective for the 3D printer to predictively print to stock based on a threshold that depends on the system’s status. We also identify a printing mode called predictive print on demand that allows for minimal inventory, and we find the speed of 3DP to be the primary factor that influences its optimality. Furthermore, we assess the value of IoT in cost reductions by separately analyzing the impact of advance information from embedded sensors and the real-time information fusion through IoT. We find that IoT provides significant value in general. However, the conventional wisdom that IoT’s value scales up for larger systems is suitable only when the expansion is paired with appropriate 3DP capacity. Our framework can help inform investment decisions regarding IoT/embedded sensors and support the development of scheduling tools for predictive 3DP. This paper was accepted by David Simchi-Levi, operations management. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2023.00978 .

Evolution of On-demand Printing Machines and Media Development

Evolution of On-demand Printing Machines and Media Development

Hydrothermal Treatment via Microwave Radiation Improves Viscoelastic Properties of Native Gluten-Free Flours for Extrusion 3D Printing

The market for gluten-free products is experiencing significant growth due to the increase in the number of gluten/wheat affected patients diagnosed, but largely as a result of the emergence of a new niche market dedicated for consumers who optionally avoid gluten. Native flours are perceived as viable alternative for industrially used starch and hydrocolloids blends, mainly due to their lack of vitamins and minerals, which are abundant in non-refined raw materials. Edible inks for on-demand printing are under significant consideration, while texture building capacity remains an issue. As heat-moisture treatment has proved to be useful for stabilizing the pasting and rheological behavior of various native flours, HMT supported by microwave heating was investigated as printable ink stabilizers. For Spanish and Polish buckwheat flours and two different varieties of teff (white and brown) flour pasting, structural and textural characteristics after the microwave supported heat moisture treatment in 30% of initial moisture content were evaluated. The peak viscosity was reduced by 54% and 60% for Polish and Spanish flour, respectively, while for teff, the reduction was 15% and 43% for the white and brown varieties, respectively. Significant improvement in viscoelastic modulus G’ (for Polish and Spanish buckwheat flour, 32% and 16%, respectively; for white and brown tef varieties, 14% and 18%, respectively) was observed for all the treated samples regardless of the species or variety; this resulted in better performance during 3D printing.

INFLUENCE OF THE BUILD AXIS AND ANGLE ON THE PROPERTIES OF 3D PRINTED PLA

Additive manufacturing is one of the sought-after methods for on-demand printing of customized parts. Although it has several advantages, namely design complexity, topologically optimized parts, tool-less and inventory-less manufacturing, etc., it also has challenges in terms of print parameter-dependent mechanical properties. The present paper studies the influence of the build orientation and angle on the tensile and flexural properties of fused-deposition-modelling (FDM) printed polylactic acid (PLA) samples. The samples are printed in different orientations including 0°, 15°, 30°, 45°, 60°, 75° and 90° with respect to the X- and Y-axis. From the tensile and flexural studies, we can infer that the orientation of the print plays a significant role, influencing the tensile and flexural properties. The X-axis build orientation and 75° build angle are preferred owing to better tensile and flexural properties compared to the other angles and Y-orientation.

A Comparison of the Damage Tolerance of AA7075-T6, AA2024-T3, and Boeing Space, Intelligence, and Weapons Systems AM-Built LPBF Scalmalloy

This paper first presents the results of an experimental study into the damage tolerance of AA7075-T6, which is widely used in both fixed- and rotary-wing aircraft, space structures, and laser bed powder fusion (LBPF) Scalmalloy specimens built by Boeing Space, Intelligence, and Weapons Systems. To this end, four single edge notch AA7075-T6 specimens and four identical single edge notch LBPF Scalmalloy specimens were tested. The resultant crack growth curves reveal that Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy is more damage tolerant than conventionally built AA7075-T6. This finding leads to the observation that the da/dN versus ΔK curves associated with Scalmalloy and conventionally manufactured AA2024-T3 are similar. These findings highlight the potential for Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy to be used to extend the operational lives of military aircraft by the on-demand printing of limited-life Scalmalloy replacement parts.

Printing Polymeric Convex Lenses to Boost the Sensitivity of a Graphene-Based UV Sensor.

Ultraviolet (UV) is widely used in daily life as well as in industrial manufacturing. In this study, a single-step postprocess to improve the sensitivity of a graphene-based UV sensor is studied. We leverage the advantage of electric-field-assisted on-demand printing, which is simply applicable for mounting functional polymers onto various structures. Here, the facile printing process creates optical plano-convex geometry by accelerating and colliding a highly viscous droplet on a micropatterned graphene channel. The printed transparent lens refracts UV rays. The concentrated UV photon energy from a wide field of view enhances the photodesorption of electron-hole pairs between the lens and the graphene sensor channel, which is coupled with a large change in resistance. As a result, the one-step post-treatment has about a 4× higher sensitivity compared to bare sensors without the lenses. We verify the applicability of printing and the boosting mechanism by variation of lens dimensions, a series of UV exposure tests, and optical simulation. Moreover, the method contributes to UV sensing in acute angle or low irradiation. In addition, the catalytic lens provides about a 9× higher recovery rate, where water molecules inside the PEI lens deliver fast reassembly of the electron-hole pairs. The presented method with an ultimately simple fabrication step is expected to be applied to academic research and prototyping, including optoelectronic sensors, energy devices, and advanced manufacturing processes.

Biodesigned bioinks for 3D printing via divalent crosslinking of self-assembled peptide-polysaccharide hybrids

The demands of tissue engineering and regenerative medicine require biomaterials to be accurately deposited into biomimetic shapes, support cellular behaviour and lead to functional tissue formation. Bioinspired yet synthetic biomaterials offer significant advantages over processed, animal-derived products; including high reproducibility and clinical compliance and specific engineered biomimicry of architecture and biological function. Self-assembling peptides are synthetic highly hydrated scaffolds that are rationally designed to mimic the extracellular matrix of a target tissue. Due to the potential benefits of chemically synthesised self-assembling peptides for clinical translation, their development into tools for biofabrication is warranted. However, these systems can be poorly suited to the demands of biofabrication, particularly when functionalised toward tissue-specific conditions. Here, we demonstrate how to improve biofabrication of self-assembling peptides. The fibrillar network arising from the self-assembling peptide Fmoc-FRGDF (containing cell attachment motif RGD) is combined with the robust polysaccharides agarose and alginate demonstrating enhanced printability and cellular compatibility. This study provides a robust methodology for the on-demand printing of personalised implants with a clinically relevant material.

On-demand direct printing of tin microdots by a piezoelectric microjet: design, simulation, and experimental evaluation

Metal microdot precision printing is widely applied in flexible circuit manufacturing, ball grid array and additive manufacturing, etc. Compared with indirect metal microdot printing, direct printing can realize high efficiency printing by directly ejecting hot-melt metal droplets. While, due to the compressibility of the driving gas, uniform printed microdots are hardly to be obtained by using the existing direct printing method. In this work, a piezoelectric microjet, which can print tin microdots directly by the drive of piezoelectric actuator without complex pneumatic system, is designed. Optimization analyses of the displacement amplifier are carried out to obtain high amplification efficiency for realizing hot-melt droplet ejection and effective heat insulation. The forming, spreading, and solidification processes of the ejected hot-melt tin droplets are discussed, and the printing mechanism is revealed. Based on experimental research, the influences of the excitation parameters and the target surface characteristics on the morphology and size of the printed tin microdots are studied, and the methods to meet different printing requirements are proposed. Tin microdot diameter of 340 μm can be printed on the surface with temperature of 120 °C when voltage pulse with amplitude of only 16 V is applied on the designed piezoelectric microjet with the nozzle diameter of 200 μm. The feasibility and controllability of the tin microdot printing methods are verified by two-dimensional printing and three-dimensional deposition printing test. This work can provide important reference for on-demand printing of metal microdots.

On the suitability of insourced Additive Manufacturing for spare parts management

Additive Manufacturing (AM) has recently emerged as a promising technique in spare parts manufacturing. Unlike conventional manufacturing (CM) techniques, AM can lead to a reduction in inventory levels, particularly when insourced, through manufacturing spare parts on demand. However, due to the high production costs, the economic benefits of manufacturing spare parts through AM are unclear to managers and practitioners. Recent studies aimed at assisting in this decision have two main limitations: (i) they assume that AM spare parts typically have higher failure rates than CM parts: and (ii) they do not consider the AM machinery investment costs and parts are assumed to be externally supplied. We have developed a model that overcomes these limitations, first by assessing the failure rates of AM spare parts through an interdisciplinary approach rather than making arbitrary assumptions, which enables a comparison with the failure rates through CM reported in the literature. Second, we considered that the manufacturing of AM spare parts can be insourced and thus the investment costs for AM printers are also included, while the manufacturing of CM spare parts is considered to be outsourced. The model was tested with unconstrained and constrained stock systems, and clearly demonstrates the advantages of an insourced 3D printer for on-demand printing under constrained stock systems. Neither is AM preferable under an unconstrained system, due to the high costs of purchasing the printer and of production.

A movable type bioelectronics printing technology for modular fabrication of biosensors

Biosensors have been widely used in various fields such as food industry, environmental testing and medical testing for their high sensitivity. However, current fabrication methods of biosensors, such as screen printing, micro fabrication and 3D printing suffer from complex procedures, requirement of cleanroom facility and limited fabrication materials, which significantly restrict the development and utilization of biosensors. Here, we propose a movable type bioelectronics printing method for the fabrication of biosensors by directly transferring bioelectronic materials onto various substrates using pre-fabricated molds. This simple, low-cost, yet robust method facilitates on-demand printing of master molds of partial or complete circuits on both rigid or flexible substrates. With this method, bioactive materials such as enzymes can be directly transferred onto substrates together with other electronic components, without complex modification after electrode fabrication using conventional methods. For demonstration, a dual-channel flexible electrochemical biosensor was fabricated by the movable type bioelectronics printing method for continuous monitoring of glucose and lactate. The movable type bioelectronics printing technology holds advantages of repeatability, flexibility and low cost for fabrication of biosensors on rigid and flexible substrates, as well as direct transfer printing of bioactive materials, which greatly promotes small-scale production of biosensors.

3D printed biomimetic cochleae and machine learning co-modelling provides clinical informatics for cochlear implant patients

Cochlear implants restore hearing in patients with severe to profound deafness by delivering electrical stimuli inside the cochlea. Understanding stimulus current spread, and how it correlates to patient-dependent factors, is hampered by the poor accessibility of the inner ear and by the lack of clinically-relevant in vitro, in vivo or in silico models. Here, we present 3D printing-neural network co-modelling for interpreting electric field imaging profiles of cochlear implant patients. With tuneable electro-anatomy, the 3D printed cochleae can replicate clinical scenarios of electric field imaging profiles at the off-stimuli positions. The co-modelling framework demonstrated autonomous and robust predictions of patient profiles or cochlear geometry, unfolded the electro-anatomical factors causing current spread, assisted on-demand printing for implant testing, and inferred patients’ in vivo cochlear tissue resistivity (estimated mean = 6.6 kΩcm). We anticipate our framework will facilitate physical modelling and digital twin innovations for neuromodulation implants.

3D printing of highly reactive silicones using inkjet type droplet ejection and free space droplet merging and reaction

Additive manufacturing and 3D printing technology using thermoplastics and metals have found mainstream use and acceptance. Nevertheless, these methods are not suitable for several industrially important materials, such as silicones and epoxies that are formed by mixing two or more reactive components and chemically inducing crosslinking. The reaction increases the viscosity of the material significantly, which greatly affects the printing process. Here, we develop an inkjet-based printing method that generates droplets of the reactive components simultaneously, merges and mixes them in free space and deposits these curing droplets so that 3D structures can be formed. It uses low viscosity, highly reactive silicone inks that cannot be printed using conventional methods of additive manufacturing and expands the range of 3D printable materials. The method enables stable and uninterrupted printing and allows for multi and rapid start-stop cycles. The high reactivity of the ink used allows printing of high aspect ratio features, as well as structures that do not require supporting scaffolds. The capabilities of the new printing method, such as non-contact printing, on-demand printing, and the ability to handle highly reactive materials make it suitable for a wide range of industrial and home use of 3D printing technology for non-thermoplastic polymeric materials.

Publishing in the UK

The UK publishing industry is one of the most powerful in the world. Our intelligence has shown that the global status of the industry is determined by the leadership of the English language in the world stage, heritage, historical ties and the force of copyright law.
 The article proves that the United Kingdom is a leader in many areas of publishing, such as the publication in English of works from other cultures: African, Caribbean and Indian literature. British publishers are also competitive in areas such as textbooks, various reference books, English Language Guides (ELTs) and textbooks for international schools.
 An analysis of the Global Publishers' Rating in 2017 showed how British publishing companies are constantly succeeding on the world stage. For example, according to the Global Publishers' Rating in 2017, five British companies earned a quarter of the combined revenue of the world's 50 most powerful firms. (For comparison: eight US publishers together earned 27% and together — more than half.) The printing industry in the UK is large, developed and thriving. The United Kingdom is the fifth largest producer of printed matter in the world, employing around 116 000 people and accounting for £ 5,8 billion in GDP.
 The performance of the UK book publishing industry is the printing of new titles and new publications. According to this indicator of publishing productivity, the British book industry is a world leader. In 2014, the American book publishing industry estimated that 335 000 new titles and publications were published, followed by China with 448 000, the United Kingdom with 220 000, well ahead of Japan, Germany, and Russia, as well as France, Italy, and Spain. If we use a different method of counting and find out the number of new names printed per million population, it turns out that the UK produces the most new names in the world — more than 2900 per million population against 1000 to 1500 for other large developed markets.
 An analysis of the book industry in the United Kingdom shows that it is constantly evolving. Modern digital technologies allow publishing companies to reorganize and improve technological processes. New features include: integration with supply chain partners, online distribution, dynamic pricing, on-demand printing, e-book publishing.

Collaborative Teams for Self-Publishing: A model for creating locally-relevant educational books

Transforming education often means finding new curricular materials that are culturally relevant to local schools. If no such books are available, new materials need to be created to meet specific needs. Producing new high-quality materials may seem out of reach to educators who lack experience in illustration and publishing or have little access to commercial publishers.
 We share a model used to develop a series of books called Conservation Tales in collaboration with university faculty students, and scientists. The model is presented as a way for local educators to create books to make education more relevant and accessible for children. The model leverages skills of artists, writers, and content experts to provide a rich learning experience for readers and an affordable option for self-publishing.
 The model allowed a science educator to develop books for grades 3-5 with illustrations and photographs. University students were selected to developed images, create page layouts, and co-author the stories to suit the target audience. Collaborators also included scientists who reviewed content for accuracy and education students who developed learning activities included in the books.
 This article describes the collaborative model with examples, and shares the process for self-publishing of print and digital books via online on-demand print services. We discuss sites that allow authors to create books with almost no overhead budget. We also share tips about the quality of graphics, software for creating files, and distributing your books.
 Keywords: Self-publishing, Culturally relevant books, collaborative writing

Functional Materials for Two-Photon Polymerization in Microfabrication.

Direct laser writing methods based on two-photon polymerization (2PP) are powerful tools for the on-demand printing of precise and complex 3D architectures at the micro and nanometer scale. While much progress was made to increase the resolution and the feature size throughout the years, by carefully designing a material, one can confer specific functional properties to the printed structures thus making them appealing for peculiar and novel applications. This Review summarizes the state-of-the-art of functional resins and photoresists used in 2PP, discussing both the range of material functions available and the methods used to prepare them, highlighting advantages and disadvantages of different classes of materials in achieving certain properties.

An integrated cell printing system for the construction of heterogeneous tissue models

A new three-dimensional (3D) cell printing system was developed and investigated to organize multiple cells/biomaterials with a control precision within 100 μm. This system can be used for the in vitro construction of heterogeneous tissue models. The proposed printing system was achieved by the integration of extrusion printing and alternating viscous and inertial force jetting (AVIFJ) techniques using dual-nozzle switching. In this technique, hydrogels containing high cell densities were extruded using extrusion printing, while droplets containing single cells were precisely manipulated using AVIFJ. The droplets that contained single cells were at the scale of pico-liters and could be accurately positioned at the micron scale. Stable hydrogel structures with adjustable diameters were also printed, with cell viabilities exceeding 90% after printing. A heterogeneous tumor model that contained spheroids and human umbilical vein endothelial cells (HUVECs) was then constructed using the established integrated cell printing system in a stepwise or simultaneous fashion. HUVEC-loaded droplets were observed to locate around the preformed tumor spheroids as designed. Cells and spheroids in the model maintained high cell viability and sustained growth throughout the culture period. The ELISA results of albumin production also proved that the spheroids maintained increased cellular function during the culture. These results demonstrated the feasibility of this integrated 3D printing system for the engineering of in vitro heterogeneous tissue models for future biological and pathological studies. Statement of SignificanceAddressing the challenge of multi-scale printing in the construction of heterogeneous tissue models, a new 3D cell printing system was developed to organize cells/biomaterials of a control precision within 100 μm. AVIFJ was integrated with extrusion printing, thereby achieving the construction of cell interactions between single cells and spheroids, the manipulation of single cells in a 3D microenvironment with high accuracy, and the real-time on-demand printing. The printed heterogeneous tumor model maintained cell viability, sustained cell growth, and increased cell function during 7 days of culture. We believed that this work would benefit the production of functional artificial tissues, enabling the construction of more biomimetic cell arrangements and microenvironment to support cell functions.

3D Bioprinted Nanocellulose-Based Hydrogels for Tissue Engineering Applications: A Brief Review.

Nanocellulosic materials, such as cellulose nanocrystals, cellulose nanofibers, and bacterial nanocellulose, that display high surface area, mechanical strength, biodegradability, and tunable surface chemistry have attracted great attention over the last decade for biomedical applications. Simultaneously, 3D printing is revolutionizing the field of biomedical engineering, which enables the fast and on-demand printing of customizable scaffolds, tissues, and organs. Nanocellulosic materials hold tremendous potential for 3D bioprinting due to their printability, their shear thinning behavior, their ability to live cell support and owing to their excellent biocompatibility. The amalgamation of nanocellulose-based feedstocks and 3D bioprinting is therefore of critical interest for the development of advanced functional 3D hydrogels. In this context, this review briefly discusses the most recent key developments and challenges in 3D bioprinting nanocellulose-based hydrogel constructs that have been successfully tested for mammalian cell viability and used in tissue engineering applications.

Preventive Maintenance with a 3D Printing Option

Additive manufacturing (AM) technology, or 3D printing as it is otherwise known, has been developing rapidly. Among other things, it enables on-demand printing of spare parts via local 3D printing hubs. This theoretically eliminates the need for firms to keep spare parts inventory, even though such printed parts may not be as reliable as regular spare parts. To investigate this trade-off we develop two age-based preventive maintenance policies in which on-demand printed parts are used to protect against long system downtime. In the first policy the printed parts are only used temporarily, i.e., until a regular spare part arrives, while in the second policy the printed parts are subject to their own age-based preventive maintenance threshold. These printing policies are benchmarked against a common age-based preventive maintenance policy for which a regular part is held on stock. We find that the printing policies outperform this benchmark in terms of costs in many cases, but not in all. Specifically, on-demand printing should be used in a preventive maintenance setting when holding costs and direct failure costs are high. We furthermore find only small difference in performance between the two printing policies. These parts should be subjected to a preventive maintenance threshold only when printed parts are expected to last for a significant amount of time (i.e., several times the magnitude of the regular spare part lead time).

Random Walk-Based Semantic Annotation for On-demand Printing Products

Nowadays, the scale of real network is increasing day by day, while also brings sparse problems. It is usually necessary to maintain a large number of product information. To organize this product information, a feasible way is to add semantic tags to the information. In this article, we aim to solve the problem of semantic annotation of on-demand printing products. Based on good properties of random walk in global networks, we deal with the sparsity problem by applying it, and then propose an efficient ProRWR algorithm. Firstly, it processes the text description dataset of printed products based on TF-IDF algorithm, and builds “product-term” bipartite network. Secondly, ProRWR builds square matrix using the TF-IDF weight matrix, rewrite the equation of random walk, and use the normalized square matrix as the input of rewrite ProRWR algorithm. By random walks, terms with the highest convergence probability in each product document are selected as the most relevant feature terms of the product. A large number of experiments have been done on Amazon dataset. The results show that the precision and recall of our algorithm are 73.5% and 60%, respectively, indicating that ProRWR has discovered the potential semantic association and implemented the semantic annotation of on-demand printed products.