Printing Devices Research Articles

Comparison of model materials for investment casting made by rapid prototyping

This paper deals with a comparison of different materials to produce models for investment casting technology using additive manufacturing methods. The work is focused on three materials for FDM type printers, as well as two resins for SLA printing devices. To create a comprehensive image of each filament the materials are presented in terms of technology, the need for additional post processing, as well as physical and mechanical properties for each product.

High-Strength, Large-Deformation, Dual Cross-Linking Network Liquid Crystal Elastomers Based on Quadruple Hydrogen Bonds.

Liquid crystal elastomers (LCEs) with large deformation under external stimuli have attracted extensive attention in various applications such as soft robotics, 4D printing, and biomedical devices. However, it is still a great challenge to reduce the damage to collimation and enhance the mechanical and actuation properties of LCEs simultaneously. Here, we construct a new method of a double cross-linking network structure to improve the mechanical properties of LCEs. The ureidopyrimidinone (UPy) group with quadruple hydrogen bonds was used as the physical cross-linking unit, and pentaerythritol tetra(3-mercaptopropionate) was used as the chemical cross-link. The LCEs showed a strong mechanical tensile strength of 8.5 MPa and excellent thermally induced deformation (50%). In addition, the introduction of quadruple hydrogen bonds endows self-healing ability to extend the service life of LCEs. This provides a generic strategy for the fabrication of high-strength LCEs, inspiring the development of actuators and artificial muscles.

A video auditing system for display-based voting machines

The use of general-purpose computers as touch-screen voting machines has created several difficult auditing problems. If voting machines are compromised by malware, they can adapt their behavior to evade testing and auditing, and paper trails are achieved through printing devices under the untrusted machine’s control. In this paper we outline and exhibit a prototype of a device that audits a voting machine through screen capture, sampling the HDMI signal passed from the computer to the display. This is achieved through a standard that requires a compliant voting machine to display signal markers on the summary pages before a vote is cast; compliance is enforced via alerts to the voter with a visual and audible signal while the screen is captured and archived. This direct feedback to the voter prevents a compromised machine from failing to invoke the device. We discuss the design and prototype of this system and possible avenues for attack on it.

Contributions of Information and communication technologies to industrialization of additive manufacturing

Additive manufacturing is in clear progress in the field of civil engineering construction, essentially boosting by the development of new information and communication technologies. For better industrialization of the use of this technique, in-situ control of products manufactured along the production line is a major issue. In this work we were able to supervise the quality of printed object along the process by comparing the target values and those measured by image processing obtained by a camera installed in the printing device. We have developed a program that allows us to measure the deformations of the different layers and thus to assess the difference between the values of the target ratings and those achieved. This deviation is defined as a criterion for validating piece conformity and can also be used to adapt the process parameters.

Evaluation of the accuracy of dental casts manufactured with 3D printing technique in the All-on-4 treatment concept.

The aim of this study is to compare the casts obtained by using conventional techniques and liquid crystal display (LCD) three-dimensional (3D) print techniques in the All-on-4 treatment concept of the edentulous mandibular jaw. In this study, a completely edentulous mandibular acrylic cast (typodont) with bone-level implants placed with the All-on-4 technique served as a reference cast. In this typodont, impressions were taken with the conventional technique and dental stone casts were obtained. In addition, after scanning the acrylic cast in a dental laboratory scanner and obtaining the Standard Tessellation Language (STL) data, 3D printed casts were manufactured with a 3D printing device based on the design. The stone and 3D printed casts were scanned in the laboratory scanner and STL data were obtained, and then the interimplant distances were measured using Geomagic Control X v2020 (3D Systems, Rock Hill, SC, USA) analysis software (n = 60). The obtained data were statistically evaluated with one-way analysis of variance (ANOVA) and Tukey's pairwise comparison tests. As a result of the one-way ANOVA test, it was determined that the stone casts, 3D printed casts, and reference cast values in all distance intervals conformed to the normal distribution and these values had a significant difference among them in all distance intervals. In Tukey pairwise comparison test, significant differences were found between casts at all distance intervals. In all analyses, the level of significance was determined as .05. 3D printed casts obtained with a 3D LCD printing device can be an alternative to stone casts when implants are placed in edentulous jaws.

Digital printing trends

The analysis of the digital printing concept is carried out, the current state and immediate prospects of digital printing methods are studied. This issue is especially relevant in connection with the large-scale jump of the most traditional technologies. Keywords publishing house, printing, digital printing, services market, ratio, digital printing devices, development prospects

A metallosupramolecular polymer deposited via inkjet printing for fast-switching pixelated electrochromic devices

We investigated the process of patterning an Fe(II)-MEPE film on an ITO-coated PET film using a commercially available inkjet printing device and developed an optimal ink formulation consisting of water/ethanol/ethylene glycol for inkjet printing.

Document Recapture Detection Based on a Unified Distortion Model of Halftone Cells

In recent years, digital copies of paper documents are used widely with the prevalence of various online services. As a result, it is critical to validate the authenticity of the uploaded document images to protect against attacks from malicious users. Out of various types of attacks, the recapture attack (by reprinting and recapturing) is effective in concealing the trace of document forgeries. However, detecting the recaptured document images is challenging. To address this problem, we first study the halftone cell distortion introduced in both the genuine and recaptured document images. Based on our study, a unified model that characterizes the halftone cell distortion (e.g., errors in size and displacement) is then proposed for accurate estimation of the distortion parameters. The statistics of the estimated parameters are then exploited in a hypothesis testing framework to detect the recaptured document images. The questioned document image can be authenticated by testing against the null hypothesis, i.e., the image is a genuine sample. To evaluate the performance of the proposed approach under different application scenarios, extensive experiments are conducted with different prior knowledge of printers (known printer model, known printing technique, and In-The-Wild (unknown printing device and document contents)). The experiment results show that the proposed approach outperforms the data-driven benchmark approaches by a significant margin. Specifically, under the In-The-Wild experiment protocol, the Area Under the Receiver Operating Characteristic (ROC) Curve (AUC) of the proposed approach is above 0.87 while the AUC of the benchmark approaches (even some utilize both genuine and recaptured samples) degrades to less than 0.77.

3D Printing of Copper Using Water-Based Colloids and Reductive Sintering.

Copper was manufactured by using a low-cost 3D printing device and copper oxide water-based colloids. The proposed method avoids the use of toxic volatile solvents (used in metal-based robocasting), adopting copper oxide as a precursor of copper metal due to its lower cost and higher chemical stability. The appropriate rheological properties of the colloids have been obtained through the addition of poly-ethylene oxide-co-polypropylene-co-polyethylene oxide copolymer (Pluronic P123) and poly-acrylic acid to the suspension of the oxide in water. Mixing of the components of the colloidal suspension was performed with the same syringes used for the extrusion, avoiding any material waste. The low-temperature transition of water solutions of P123 is used to facilitate the homogenization of the colloid. The copper oxide is then converted to copper metal through a reductive sintering process, performed at 1000°C for a few hours in an atmosphere of Ar-10%H2. This approach allows the obtainment of porous copper objects (up to 20%) while retaining good mechanical properties. It could be beneficial for many applications, for example current collectors in lithium batteries.

Applying CRISPR/Cas system as a signal enhancer for DNAzyme-based lead ion detection

Heavy metal lead accumulation in the environment pollutes the ecology systems and further threatens the human health. It is necessary to develop a sensitive method to detect it. Here, we propose a highly sensitive lead detection method by combining DNAzyme and CRISPR system. Once the lead ion is recognized, the substrate chain of DNAzyme is cleaved to produce single strand DNA. The produced single strand DNA can be detected by Cas protein/guide RNA complex and further trigger the collateral cleavage effect of CRISPR system, which can indiscriminately cut short single strand DNA reporters. By this way, the detection signals can be greatly amplified. This method can detect lead ions as low as 0.48 nM. The sensitivity is higher than the DNAzyme method. Furthermore, the portable 3D printing device is designed to observe the fluorescent signals so the end-point detection results can be visualized by the naked eyes. The entire detection process can avoid using bulky and expensive instruments, which can promote on-site lead ion detection.

Design and Implementation of 3D Printing Using a Universal Printing System on the Robot Arm UR5

The combination of two rapidly evolving technologies such as additive manufacturing technology and robotics opens up a wide potential for solving new production tasks. In advance, several challenges need to be addressed in order to intensify the possibilities for developing the combination of these technologies. The aim of the article is to point out the possibility of designing a simple universal printing system for the collaborative robot UR5 with an orientation on the need to implement 3D printing. The solution proposed in this way makes it possible to simplify the design of the movements to reduce any further structural modifications and also to reduce the potential mechanical deficiencies of the structure of the printing device.

Проектирование деталей с учетом трехмерной технологии их изготовления

The paper studies the issues of the development of parts and assemblies taking into account the technology of three-dimensional printing. The analysis of the identification of design parameters and three-dimensional printing device parameters for obtaining a finished product of the required dimensions and strength is carried out.

Optimal Location-Allocation of Printing Devices for Energy Saving Using a Novel MILP Approach

In recent years, a growing number of enterprises have taken different steps to reduce the energy consumption and carbon emissions of information and communication technology (ICT) assets. Because of the expansion of digitalization and the need for rapid access to information, enterprises have been compelled to optimize the location and utilization of their ICT hardware. In this context, this paper presents a novel method based on a mixed-integer linear programming approach for optimizing the physical location and task allocation of printing devices in office floor plans considering the power usage of the ICT assets, the costs related to the purchase and service of the individual devices, operating costs, and distance between employees and printing devices. The applicability of the proposed model is illustrated using the case study of a company with 100 functional departments located in several office buildings across Poland. The results reveal that the model guarantees the execution of all printing tasks and satisfies the functionality requirements expressed by the users of the workstations. Moreover, the selection of more energy-efficient printing devices leads to a considerable reduction in electricity consumption, related not only to the direct operation of these devices but also to their modes of operation (work, idle, or sleep). Such results also bring tangible effects in reducing carbon dioxide emissions, which is particularly important for businesses operating in countries where fossil fuels still dominate the energy mix.

Обеспечение безопасности органов внутренних дел в ходе профессионального психологического отбора на службу с помощью полиграфных устройств

the article discloses the main results of the study, describing the dependence of the presence of risk factors on the personal characteristics of candidates for service in the internal affairs bodies in the process of conducting a special psychophysiological study using a polygraph.
 The main conclusions in this study were obtained using comparative, qualitative, correlation and frequency analyses, which is confirmed by the existence of numerous relationships of personal characteristics, according to which the presence or absence of risk factors can be predicted. This empirical study has made it possible to draw up a table of the distribution of specific gravity and a formula according to which an employee working with printing devices can calculate the probability of identifying a risk factor in each candidate for service in the internal affairs bodies on the basis of a psychological examination. The obtained data on the results of the methods used, describing various aspects of the external manifestations of a person, were presented by groups, in matrix form and analyzed by a number of indicators such as: the risk factor was not identified, the risk factor was identified, and in groups where the result was not determined, but there is a suspicion of the presence of a risk factor. Data were compared with intergroup measures of personality traits. Analysis of personality characteristics showed that in a sample of candidates for service, the most important of the suitability markers correlate with personal features. An employee working with printing devices at the stage of familiarization with the candidate's questionnaire, analyzing his personal and business qualities, can predict, with a high degree of probability, the identification of risk factors, even before the start of the study using a polygraph, or the manifestation of various kinds of opposition, in order to hide the identification of risk factors.
 The use of this formula by psychologists and polygraphologists in professional psychological selection greatly contributes to ensuring the safety of internal affairs bodies at the stage of personnel screening, which is aimed at detecting and preventing emergency incidents among the personnel of internal affairs bodies and occupies a decisive role in forming a positive image of the Ministry of Internal Affairs.

Comparative analysis of mechanical properties of orthodontic aligners produced by different contemporary 3D printers.

ObjectiveThe aim of this study was to compare the mechanical properties of orthodontic aligners among different commercially available 3D printing devices.Materials and MethodsFive 3D printers (Ka:rv LP 550, Swinwon; “KAR”), (L120, Dazz 3D; “L12”), (MiiCraft 125, Miicraft Jena; “MIC”), (Slash 2, Uniz; “SLS”) and (Pro 95, SprintRay; “PRO”) were used to prepare orthodontic aligners with dental resin (Tera Harz TC‐85DAW, Graphy). The central incisors of each aligner were cut, prepared and evaluated in terms of Martens‐Hardness (HM), indentation‐modulus (EIT) and elastic‐index (ηIT) as per ISO14577‐1:2002. Force‐indentation curves were recorded and differences among printers were checked with generalized linear regressions (alpha=5%).ResultsStatistically significant differences were seen for all mechanical properties (P < .05), which were in descending order: HM (N/mm2) as median (Interquartile Range [IQR]): SLS 108.5 (106.0‐112.0), L12 103.0 (102.0‐107.0), KAR 101.5 (97.5‐103.0), MIC 100.0 (97.5‐101.5) and PRO 94.0 (93.0‐96.0); EIT (MPa) as mean (Standard Deviation [SD]): SLS 2696.3 (124.7), L12 2627.8 (73.5), MIC 2566.2 (125.1), KAR 2565.0 (130.2) and PRO 2491.2 (53.3); and ηIT (%) as median (IQR): SLS 32.8 (32.3‐33.1), L12 31.6 (30.8‐32.3), KAR 31.3 (30.9‐31.9), MIC 30.5 (29.9‐31.2) and PRO 29.5 (29.1‐30.0). Additionally, significant differences existed between liquid crystal display (LCD) and digital light processing (DLP) printers for HM (P < .001), EIT (P = .002) and ηIT (P < .001), with aligners from the former having higher values than aligners from the latter printer.ConclusionUnder the limitations of this study, it may be concluded that the mechanical properties of 3D‐printed orthodontic aligners are dependent on the 3D printer used, and thus, differences in their clinical efficacy are anticipated.

Arduino Based Electronic Voting Machine

Biometric Finger print devices are used in the Electronic Voting machine for voter verification. We have designed a finger print based voting machine where there is no need for the user to carry his ID which contains his required details. The person at the polling booth needs only to place his Finger on the device, thus allowing the acquisition of an on-spot fingerprint from the voter which serves as an identification. This Finger print reader reads the details from the tag. This data is passed onto the controlling unit for the verification. The controller fetches the data from the reader and compares this data with the already existing data stored during the registration of the voters. If the data matches with the pre-stored information of the registered fingerprint, the person is allowed to cast his vote. If not, a warning message is displayed on LCD and the person is barred from polling his vote. The vote casting mechanism is carried out manually using the push buttons. And the handicapped people and others like those who are not having their fingerprints properly, they are allowed to cast their vote using Radio Frequency ID tag and it helps them to cast their vote without any fingerprints. LCD is used to display the related messages, warnings and ensuing results.

3D Printing of Graphite Electrode for Lithium‐Ion Battery with High Areal Capacity

Combined with the traditional preparation method of graphite anode slurry for lithium battery and the manufacturing technology of pneumatic jet, the organic solvent‐based anode slurry is selected to explore the viscosity curve under different solid–liquid ratios. It is judged that the anode slurry is a non‐Newtonian fluid. It has printability and meets the requirements of direct writing molding technology. The slurry with a solid volume fraction of 50% is selected as the printing material, the graphite anode slurry is molded on the copper foil by a pneumatic printing device and the electrochemical performance of the coin lithium‐ion battery is analyzed. The effect of printing structure and printing interval on the electrochemical performance of lithium‐ion batteries is studied and compared with batteries prepared by traditional coating processes. Finally, the linear electrode pattern is selected to discuss the effect of printing layers on the electrochemical performance of lithium‐ion batteries. The results show that the areal specific capacity of the printed electrode is significantly higher than that of the traditional coated electrode and the shape, interval, and the number of layers of the printing electrode have a significant effect on the performance of the battery.

Biomimetic 4D‐Printed Breathing Hydrogel Actuators by Nanothylakoid and Thermoresponsive Polymer Networks

AbstractShape‐morphing actuators, which can breathe with the accompany of morphology changes to mimic botanical events, are challenging to fabricate with soft hydrogel materials. Herein, 4D printed‐smart hydrogel actuators are reported that can not only dynamically deform but also generate oxygen (O2) upon external stimulations. The printed breathing actuators featured with spinach leaf‐derived thylakoid membrane (nanothylakoid) for photothermal conversion and catalytical O2 evolution, a poly(N‐isopropylacrylamide) (PNIPA) thermoresponsive polymer network for generating deformation forces by swelling/shrinkage (rehydration/dehydration), and an asymmetric bilayer poly(N‐isopropylacrylamide)/polyacrylamide (PNIPA/PAA) structure to amplify the mechanical motions. Upon thermal stimulation or laser irradiation, the actuator can reversibly bend/unbend because of the photothermal conversion of nanothylakoid and the printed thermoresponsive asymmetric bilayer structure. Additionally, the catalase‐like property of nanothylakoid imparts the actuator with O2 evolution capability to breathe for further mimicking botanical systems. Notably, 4D printing can greatly facilitate and simplify the actuator fabrication process, including adjusting the size and layer compositions. This artificial breathing actuator with photothermal and catalytical properties provides a strategy in designing intelligent hydrogel systems and proves to be a highly promising material candidates in the fields of 3D/4D printing, automated robotics, and smart biomedical devices.

Case Study on Augmented Reality, Digital and Physical Modelling with Mathematical Learning Disabilities Students in an Elementary School in Luxemburg

This paper reports on a case study of two elementary school students with mathematical learning disabilities (MLD) (ages 10 and 11) using augmented reality (AR), digital and physical modelling in mathematics class. MLD students worked on modelling geometric shapes (cubes, cuboids, squared pyramids, and octahedrons) and forms (polygons) by combining real-world objects with AR and creating a copy of geometric shapes or missing parts with a 3D printing device. The study focused on the development of process skills and mathematical concepts, tried to identify changes in the visualspatial memory, and documented the learning behaviour in class. Further, we collected data through task-based interviews with both students. Based on our findings, we present settings and manipulatives which are likely to foster process skills and mathematical concepts in geometry tasks suitable for MLD elementary school students.

3D-Printed COVID-19 immunosensors with electronic readout

3D printing technology has brought light in the fight against the COVID-19 global pandemic event through the decentralized and on-demand manufacture of different personal protective equipment and medical devices. Nonetheless, since this technology is still in an early stage, the use of 3D-printed electronic devices for antigen test developments is almost an unexplored field. Herein, a robust and general bottom-up biofunctionalization approach via surface engineering is reported aiming at providing the bases for the fabrication of the first 3D-printed COVID-19 immunosensor prototype with electronic readout. The 3D-printed COVID-19 immunosensor was constructed by covalently anchoring the COVID-19 recombinant protein on a 3D-printed graphene-based nanocomposite electrode surface. The electrical readout relies on impedimetrically monitoring changes at the electrode/electrolyte interface after interacting with the monoclonal COVID-19 antibody via competitive assay, fact that hinders the redox conversion of a benchmark redox marker. Overall, the developed 3D-printed system exhibits promising electroanalytical capabilities in both buffered and human serum samples, displaying an excellent linear response with a detection limit at trace levels (0.5 ± 0.1 μg·mL−1). Such achievements demonstrate advantage of light-of-speed distribution of 3D printing datafiles with localized point-of-care low-cost printing and bioelectronic devices to help contain the spread of emerging infectious diseases such as COVID-19. This technology is applicable to any post-COVID-19 SARS diseases.