10 - Functionalized 4D-printed sensor systems

The widespread application of additive manufacturing (AM) technologies, commonly known as three-dimensional (3D) printing, in industrial and home-business sectors, and the expected increase in the number of workers and consumers that use these devices, have raised concerns regarding the possible health implications of 3D printing emissions. To inform the risk assessment and management processes, this review evaluates available data concerning exposure assessment in AM workplaces and possible effects of 3D printing emissions on humans identified through in vivo and in vitro models in order to inform risk assessment and management processes. Peer-reviewed literature was identified in Pubmed, Scopus, and ISI Web of Science databases. The literature demonstrated that a significant fraction of the particles released during 3D printing could be in the ultrafine size range. Depending upon the additive material composition, increased levels of metals and volatile organic compounds could be detected during AM operations, compared with background levels. AM phases, specific job tasks performed, and preventive measures adopted may all affect exposure levels. Regarding possible health effects, printer emissions were preliminary reported to affect the respiratory system of involved workers. The limited number of workplace studies, together with the great variety of AM techniques and additive materials employed, limit generalizability of exposure features. Therefore, greater scientific efforts should be focused at understanding sources, magnitudes, and possible health effects of exposures to develop suitable processes for occupational risk assessment and management of AM technologies.

Additive manufacturing of cementitious composites: Materials, methods, potentials, and challenges

Multiscale and multimaterial three-dimensional (3D) printing is new frontier in additive manufacturing (AM). It has shown great potential to implement the simultaneous and full control for fabricated object including external geometry, internal architecture, functional surface, material composition and ratio as well as gradient distribution, feature size ranging from nano-, micro-, to macro-scale, embedded components and electrocircuit, etc. Furthermore, it has the ability to construct the heterogeneous and hierarchical structured object with tailored properties and multiple functionalities which cannot be achieved through the existing technologies. That paves the way and may result in great breakthrough in various applications, e.g., functional tissue and organ, functionally graded (FG) material/structure, wearable devices, soft robot, functionally embedded electronics, metamaterial, multifunctionality product, etc. However, very few of the established AM processes have now the capability to implement the multimaterial and multiscale 3D printing. This paper presented a single nozzle-based multiscale and multimaterial 3D printing process by integrating the electrohydrodynamic jet printing and the active mixing multimaterial nozzle. The proposed AM technology has the capability to create multifunctional heterogeneously structured objects with control of the macroscale external geometry and microscale internal structures as well as functional surface features, particularly, the potential to dynamically mix, grade, and vary the ratios of different materials. An active mixing nozzle, as a core functional component of the 3D printer, is systematically investigated by combining with the theoretical analysis, numerical simulation, and experimental verification. The study aims at exploring a feasible solution to implement the multiscale and multimaterial 3D printing at low cost.

The article presents the results of ultrasonic testing of Ti6Al4V material produced by the conventional method and the laser bed fusion method. Modern manufacturing techniques, such as additive manufacturing, allow the production of parts with complex shapes. It is important to control the condition of such components throughout their lifetime. The purpose of this article was to determine the basic acoustic properties of Ti6Al4V material produced by two different methods—bar drawing and the additive manufacturing method. On this basis, an inspection scheme was developed for adhesive joints, the components of which are made by additive manufacturing technology. The decibel drops in the amplitudes of pulses reflected from the boundary of the adhesive-Ti6Al4V-AM and adhesive-Ti6Al4V joints were determined. The decibel drops for the connection of materials made with additive technology are higher than for the material made in a conventional way. The difference in decibel drop in the amplitudes of the additive manufactured material versus the drawn rod, depending on the ultrasonic head, can be up to 60%. The results of the study provide an important practical guideline for testing adhesive joints of parts made with additive manufacturing technology.

With the development of material science, additive manufacturing technology has been employed for pelvic surgery, addressing the challenges, such as the complex structure of the pelvis, difficulty in exposing the operative area, and poor visibility, of the traditional pelvic surgery. However, only limited studies have been done to review the research hotspots and trends of the additive manufacturing technology applied for pelvic surgery. In this study, we comprehensively analyzed the literatures related to additive manufacturing technology in pelvic surgery by a bibliometrics analysis and found that additive manufacturing technology is widely used in several aspects of preoperative diagnosis, preoperative planning, intraoperative navigation, and personalized implants for pelvic surgery. Firstly, we searched and screened 856 publications from the Web of Science Core Collection (WoSCC) with TS = (3D printing OR 3D printed OR three-dimensional printing OR additive manufacturing OR rapid prototyping) AND TS = (pelvis OR sacrum OR ilium OR pubis OR ischium OR ischia OR acetabulum OR hip) as the search strategy. Then, 565 of these were eliminated by evaluating the titles and abstracts, leaving 291 pieces of research literature whose relevant information was visually displayed using VOSviewer. Furthermore, 10 publications with high citations were selected by reading all publications extensively for carefully evaluating their Titles, Purposes, Results, Limitations, Journal of affiliation, and Citations. Our results of bibliometric analysis demonstrated that additive manufacturing technology is increasingly applied in pelvic surgery, providing readers with a valuable reference for fully comprehending the research hotspots and trends in the application of additive manufacturing technology in pelvic surgery.

Additive manufacturing and 3D printing is one of the most rapidly evolving industry branches nowadays.This technology brings possibility of creating new designs and materials which military industry could adopt with its benefits.3D printing based on stereolithography method was invented in 1980s.In recent times it became more and more popular and affordable what powered up a development of these technologies and spread them into public environment.Making these technologies affordable contributed to creation of a large base of informed and experienced worker's.Additive technologies are also widely studied in many educational and scientific institutions.In this paper the impact and possibilities of use additive manufacturing in military industry mainly in terms of application of 3D printing in production of weapons and ammunition will be described.Technologies of 3D printing were listed according to normalization.Technological advancements in terms of printing methods and materials were studied.Prediction of possible usage was researched based on material studies and previous scientific papers aiming for different types of materials used in military industry like metals, composites, plastics, and explosives.Requirements on additive manufacturing technologies were defined for different types of production.Operational benefits for armed forces were also studied and finally challenges for future development of additive manufacturing in military industry were set.

Three-dimensional printed titanium pseudo-prosthesis for the treatment of a tumoral bone defect

We compare and analyze terahertz (THz) metasurfaces fabricated using two distinct additive manufacturing (AM) technologies, i.e., printable electronics (PE) and three-dimensional (3D) printing. With terahertz time domain spectroscopy (THz-TDS), the performance of these devices was investigated. Both samples’ transmission characteristics were consistent with simulation results, demonstrating the effectiveness of the manufacturing technique and that they can be widely used for bandpass filtering applications at a low cost.

Ink-jet 3D printing is a promising technology for additive manufacturing, with the potential for impacting a wide variety of industries. In traditional ink-jet 3D printing, the part is built up by depositing droplets layer upon layer in an open-loop manner. Droplet and edge dimensions are typically predicted experimentally and are assumed to remain constant through the printing process. However, there is no guarantee of consistent droplet shape and dimensions or the smoothness of the finished parts due to uncertainties in the manufacturing process. To address this issue, we propose a model-based feedback control law for ink-jet 3D printing that uses a height sensor for measuring profile height after each layer for determining the appropriate layer patterns for subsequent layers. Towards this goal, a simple model describing the relationship between profile height change and droplet deposition in the layer building process is first proposed and experimentally identified. Based on this model, a closed-loop layer-to-layer control algorithm is then developed for the ink-jet printing process. Specifically, the proposed algorithm uses a model prediction control algorithm to minimize the difference between the predicted height and the desired height and the predicted surface unevenness after a fixed number of layers. Experimental results show that the algorithm is able to achieve more consistent shapes between layers, reduced edge shrinking of the part, and smoother surface of the top layer.

Chapter 4 - Review on 3D printing of medical parts

Over the last few decades, advanced manufacturing and additive printing technologies have made incredible inroads into the fields of engineering, transportation, and healthcare. Among additive manufacturing technologies, 3D printing is gradually emerging as a powerful technique owing to a combination of attractive features, such as fast prototyping, fabrication of complex designs/structures, minimization of waste generation, and easy mass customization. Of late, 4D printing has also been initiated, which is the sophisticated version of the 3D printing. It has an extra advantageous feature: retaining shape memory and being able to provide instructions to the printed parts on how to move or adapt under some environmental conditions, such as, water, wind, light, temperature, or other environmental stimuli. This advanced printing utilizes the response of smart manufactured materials, which offer the capability of changing shapes postproduction over application of any forms of energy. The potential application of 4D printing in the biomedical field is huge. Here, the technology could be applied to tissue engineering, medicine, and configuration of smart biomedical devices. Various characteristics of next generation additive printings, namely 3D and 4D printings, and their use in enhancing the manufacturing domain, their development, and some of the applications have been discussed. Special materials with piezoelectric properties and shape-changing characteristics have also been discussed in comparison with conventional material options for additive printing.

Objective To explore the application value of three-dimensional (3D) printing in skull base tumor resection. Methods Fourteen patients accepted resection of skull base tumors in our hospital from May 2016 to November 2017 were chosen in our study; before surgery, solid models of the tumors, having bones of the skull base, tumor tissues and main blood supply arteries, were established by 3D printing; resection was simulated in these models and the surgical approaches and surgical methods were determined accordingly. The disease history, preoperative and postoperative imaging data were analyzed retrospectively. Results The mean time for making a solid model of the tumors was 18.5 h, and the cost was about 5,000 Yuan. Postoperative CT and MR imaging showed that total excision was achieved in 8 patients, subtotal excision was achieved in 5 patients, and one with tumor of the jugular foramen achieved total excision of the intracranial tumor and subtotal excision of the extracranial tumor. One patient had large hemispheric infarction after operation and decompressive craniectomy was performed; the other 13 patients recovered well without serious complications or death. Conclusion The 3D printing technique can assist the preoperative simulation and formulation of skull base tumor resection, and improve the efficiency and safety of the operation. Key words: Three-dimensional printing; Tumor of base of skull; Tumor resection

Chapter 20 - Path planning and simulation for prototyping bio-inspired complex shapes

With the development of wearable electronic devices, conductive polymer composites (CPCs) based flexible strain sensors are gaining tremendous popularity. In recent years, the applications of additive manufacturing (AM) technology (also known as 3D printing) in fabricating CPCs based flexible strain sensors have attracted the attention of researchers due to their advantages of mold-free structure, low cost, short time, and high accuracy. AM technology, based on material extrusion, photocuring, and laser sintering, produces complex and high-precision CPCs based wearable sensors through layer-by-layer stacking of printing material. Some high-performance CPCs based strain sensors are developed by employing different 3D printing technologies and printing materials. In this mini-review, we summarize and discuss the performance and applications of 3D printed CPCs based strain sensors in recent years. Finally, the current challenges and prospects of 3D printed strain sensors are also discussed to provide an insight into the future of strain sensors using 3D printing technology.

Recent developments in three-dimensional (3D) printing technology offer immense potential in fabricating scaffolds and implants for various biomedical applications, especially for bone repair and regeneration. As the availability of autologous bone sources and commercial products is limited and surgical methods do not help in complete regeneration, it is necessary to develop alternative approaches for repairing large segmental bone defects. The 3D printing technology can effectively integrate different types of living cells within a 3D construct made up of conventional micro- or nanoscale biomaterials to create an artificial bone graft capable of regenerating the damaged tissues. This article reviews the developments and applications of 3D printing in bone tissue engineering and highlights the numerous conventional biomaterials and nanomaterials that have been used in the production of 3D-printed scaffolds. A comprehensive overview of the 3D printing methods such as stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), and ink-jet 3D printing, and their technical and clinical applications in bone repair and regeneration has been provided. The review is expected to be useful for readers to gain an insight into the state-of-the-art of 3D printing of bone substitutes and their translational perspectives.