3D-Printed Waveguide Bandpass Filter with Locally Resonant Cross-Shaped Metamaterial for Improved Out-of-Band Rejection

In this paper, a novel method is proposed to effectively reduce the size of a waveguide bandpass filter (BPF). Because the metallic cavities make the conventional waveguide end up with a large geometry, especially for high-order BPFs, very compact waveguide-type resonators having metamaterial zeroth-order resonance (WG ZOR) are designed on the cross section of the waveguide and substituted for the cavities. While the cavities are half-wavelength resonators, the WG ZOR is shorter than one-eighth of a wavelength. A substantial reduction in the size and weight of the waveguide filter is observed as the resonators are cascaded in series through coupling elements in the X-band that is much longer than that in K- or Ka-bands. The proposed metamaterial filter is realized as a 3D-printed structure to be lighter and thus more suitable for low earth orbit (LEO) satellites. An X-band of 7.25–7.75 GHz is chosen to verify the method as the passband with an attenuation of 40 dB at 7.00 GHz and 8.00 GHz as the roll-off in the stopband. The BPF is manufactured in two ways, namely the CNC-milling technique and metal coating–added 3D printing. The design is carried out with a geometrical parameter of not 10−2 mm but rather 10-1 mm, which is good for manufacturers but challenging for component designers. The measurement of the manufactured metal waveguide filters reveals that the passband has about ≤1 dB and ≤−15 dB as the insertion loss and the reflection coefficient, respectively, and the stopband has an attenuation of ≤−40 dB, which are in good agreement with the results of the circuit and the simulation. The proposed filter has a length of 14 cm as the eighth-order BPF, but the conventional waveguide is 20 cm as the seventh-order BPF for the same area of the cross section.

Purpose – An increasing amount of attention is being paid to three-dimensional (3D) printing technology. The technology itself is based on diverse technologies such as laser beams and materials. Hence, 3D printing technology is a converging technology that produces 3D objects using a 3D printer. To become technologically competitive, many companies and nations are developing technologies for 3D printing. So to know its technological evolution is meaningful for developing 3D printing in the future. The paper aims to discuss these issues. Design/methodology/approach – To get technological competitiveness of 3D printing, the authors should know the most important and essential technology for 3D printing. An understanding of the technological evolution of 3D printing is needed to forecast its future technologies and build the R & D planning needed for 3D printing. In this paper, the authors propose a methodology to analyze the technological evolution of 3D printing. The authors analyze entire patent documents related to 3D printing to construct a technological evolution model. The authors use the statistical methods such as time series regression, association analysis based on graph theory, and principal component analysis for patent analysis of 3D printing technology. Findings – Using the proposed methodology, the authors show the technological analysis results of 3D printing and predict its future aspects. Though many and diverse technologies are developed and involved in 3D printing, the authors know only a few technologies take lead the technological evolution of 3D printing. In this paper, the authors find this evolution of technology management for 3D printing. Practical implications – If not all, most people would agree that 3D printing technology is one of the leading technologies to improve the quality of life. So, many companies have developed a number of technologies if they were related to 3D printing. But, most of them have not been considered practical. These were not effective research and development for 3D printing technology. In the study, the authors serve a methodology to select the specific technologies for practical used of 3D printing. Originality/value – Diverse predictions for 3D printing technology have been introduced in many academic and industrial fields. Most of them were made by subjective approaches depended on the knowledge and experience of the experts concerning 3D printing technology. So, they could be fluctuated according to the congregated expert groups, and be unstable for efficient R & D planning. To solve this problem, the authors study on more objective approach to predict the future state of 3D printing by analyzing the patent data of the developed results so far achieved. The contribution of this research is to take a new departure for understanding 3D printing technology using objective and quantitative methods.

Owing to COVID-19, the world has advanced faster in the era of the Fourth Industrial Revolution, along with the 3D printing technology that has achieved innovation in personalized manufacturing. Three-dimensional printing technology has been utilized across various fields such as environmental fields, medical systems, and military materials. Recently, the 3D food printer global market has shown a high annual growth rate and is a huge industry of approximately one billion dollars. Three-dimensional food printing technology can be applied to various food ranges based on the advantages of designing existing food to suit one’s taste and purpose. Currently, many countries worldwide produce various 3D food printers, developing special foods such as combat food, space food, restaurants, floating food, and elderly food. Many people are unaware of the utilization of the 3D food printing technology industry as it is in its early stages. There are various cases using 3D food printing technology in various parts of the world. Three-dimensional food printing technology is expected to become a new trend in the new normal era after COVID-19. Compared to other 3D printing industries, food 3D printing technology has a relatively small overall 3D printing utilization and industry size because of problems such as insufficient institutionalization and limitation of standardized food materials for 3D food printing. In this review, the current industrial status of 3D food printing technology was investigated with suggestions for the improvement of the food 3D printing market in the new normal era.

Recent advances in 3D printing technologies for wearable (bio)sensors

The surgical treatment of retroperitoneal sarcoma (RPS) is highly challenging because of its complex anatomy. In this study, the authors compared the surgical outcomes of patients with RPS who underwent surgical resection guided by three-dimensional (3D) printing technology versus traditional imaging. This retrospective study included 251 patients who underwent RPS resection guided by 3D-printing technology or traditional imaging from January 2019 to December 2022. The main outcome measures were operative time, intraoperative blood loss, postoperative complications, and hospital stay. In total, 251 patients were enrolled in the study: 46 received 3D-printed navigation, and 205 underwent traditional surgical methods. Propensity score matching yielded 44 patients in the 3D group and 82 patients in the control group. The patients' demographics and tumor characteristics were comparable in the matched cohorts. The 3D group had significantly shorter operative time (median, 186.5 minutes [interquartile range (IQR), 130.0-251.3 minutes] vs. 210.0 minutes [IQR, 150.8-277.3 minutes]; p=.04), less intraoperative blood loss (median, 300.0 mL [IQR, 100.0-575.0 mL] vs. 375.0 mL [IQR, 200.0-925.0 mL]; p=.02), shorter postoperative hospital stays (median, 11.0 days [IQR, 9.0-13.0 days] vs. 14.0 days [IQR, 10.8-18.3 days]; p=.02), and lower incidence rate of overall postoperative complications than the control group (18.1% vs. 36.6%; p=.03). There were no differences with regard to the intraoperative blood transfusion rate, the R0/R1 resection rate, 30-day mortality, or overall survival. Patients in the 3D group had favorable surgical outcomes compared with those in the control group. These results suggest that 3D-printing technology might overcome challenges in RPS surgical treatment. The surgical treatment of retroperitoneal sarcoma (RPS) is highly challenging because of its complex anatomy. The purpose of this study was to investigate whether three-dimensional (3D) printing technology offers advantages over traditional two-dimensional imaging (such as computed tomography and magnetic resonance imaging) for guiding the surgical treatment of RPS. In a group of patients who had RPS, surgery guided by 3D-printing technology was associated with better surgical outcomes, including shorter operative time, decreased blood loss, shorter hospital stays, and fewer postoperative complications. These findings suggested that 3D-printing technology could help surgeons overcome challenges in the surgical treatment of RPS. 3D-printing technology has important prospects in the surgical treatment of RPS.

Neurological tumors pose considerable challenges from the point of view of diagnosis and therapeutic management. Their location makes them difficult to study and to approach surgically, especially when

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3D printing metal implants in orthopedic surgery: Methods, applications and future prospects

Three-dimensional (3D) printing technologies differ from traditional molding and casting manufacturing processes in that they build 3D objects by successively creating layers of material on top of each other. Rooted in manufacturing research of the 1980s, 3D printing has evolved into a broad set of technologies that could fundamentally alter production processes in a wide set of technology areas. This article investigates how 3D printing technology has developed over the last few decades, how intellectual property rights have shaped this potential breakthrough innovation and how 3D printing technologies could challenge the system of intellectual property rights in the future. Patent protection seems to have played an important role in the industrial 3D printing sector. In the newly emerging personal 3D printing sector, the intellectual property system faces new challenges. Developers of personal 3D printing systems and services have to cope with large-scale infringement by end-consumers, a situation well known from digital content technologies. At the same time, the expiration of key patents on 3D printing has arguably contributed to a flourishing ecosystem of open source 3D printer hardware and software. As in other areas of innovation policy, the role of the intellectual property system in fostering innovation in 3D printing technologies is a complex one. It played a beneficial role in some instances (sometimes intended and sometimes unintended), and it may have played a neutral or detrimental role in other instances. Studying the progress of 3D printing technologies thereby also informs us about the intricate relationship between intellectual property and innovation.

The review's objectives were to discuss the understanding of 3D food printing technology, a new way of manufacturing foods, and how this technology can be applicable in the food processing industry. The 3D food printing provides a wide domain of food and nutrition-based applications. The different three-dimensional shapes of a food can be developed without the utilization of any mold by using 3D printing technology. Many industries use this technology to manufacture many distinct products. However, utilizing this technology in food processing to manufacture new foods, such as plant-based meat analogues, represents a new trend. So, it is important to understand the principle of the 3D food printing technology for applying this technology in the food processing industry properly. In this review, the mechanism of 3D food printing, evolution of this technology, ingredients compatible for this technology, pros and cons of this technology and the quality evaluation of the 3D printed foods were discussed in detail. Also, the study provided details regarding the available 3D food printers, specifications, and their price. Achieving the exact texture of the 3D printed foods prepared by conventional cooking methods is a steep challenge for this technology. 3D food printers can produce complex food models, and this technology can design unique food patterns. Selection of a printing method is important because a 3D food printing technique can be an extrusion-based printing, selective sintering printing (SLS) method, inkjet printing and binder jetting and each method has its advantages and disadvantages. Pizzas, cookies, chocolates/candies, plant-based meat/fish analogues and many more customized food products can be manufactured using a 3D food printer. Overall, 3D food printing technology has great potential as a cooking method in the food industry.

Chapter 18 - 3D printing technology in drug delivery

With the rapid development of intelligent vehicle technology, traditional vehicle design and manufacturing methods are facing many challenges. Traditional vehicle design and manufacturing methods have problems such as high cost, long development cycle and lack of personalized design. This paper took advantage of the high degree of flexibility, rapid customization and cost savings of 3D printing technology, which can provide entirely new solutions for intelligent vehicle design. This paper mainly analyzed the application of three-dimensional (3D) printing and manufacturing technology in intelligent vehicle design. In intelligent vehicle design, 3D printing can carry out 3D printed body structure design to make parts lightweight. The displacement sensor in the intelligent sensor can measure the displacement, deformation and vibration of the body components, and detect whether the body structure exceeds the safety range, which can provide safety feedback to the owner. 3D printing technology has been involved in automotive dashboard, interior design and customization. In this paper, the effects of vehicles designed under traditional methods and vehicles designed under 3D printing manufacturing technology were compared. The research and development cycle of class A, Class B, Class C and Class D in brand 1 under traditional manufacturing was 3.85 years, 3.13 years, 4.27 years and 4.32 years respectively. The R&D (research and development) cycle of grade A, B, C and D in brand 1 under 3D printing technology was 2.43 years, 2.05 years, 1.64 years and 1.73 years respectively. Under the traditional method, the average R&D cost of different levels of vehicles in brand 1, brand 2 and brand 3 was 191,000 yuan, 20900 yuan and 227,200 yuan respectively. Under 3D printing technology, the average R&D cost of different levels of vehicles in brand 1, brand 2 and brand 3 was 132,600 yuan, 145,300 yuan and 157,500 yuan respectively. The results of this paper emphasize that the application of 3D printing manufacturing technology shortens the development cycle of intelligent vehicles, reduces the development cost, and can be customized, which can be more in line with the needs of users.

Background:Surgical treatment of both-column acetabular fractures is challenging because of the complex acetabular fracture patterns and the curved surface of the acetabulum. Seldom study has compared the application of three-dimensional (3D) printing technology and traditional methods of contouring plates intra-operatively for the surgical treatment of both-column acetabular fractures. We presented the use of both 3D printing technology and a virtual simulation in pre-operative planning for both-column acetabular fractures. We hypothesized that 3D printing technology will assist orthopedic surgeons in shortening the surgical time and improving the clinical outcomes.Methods:Forty patients with both-column acetabular fractures were recruited in the randomized prospective case–control study from September 2013 to September 2017 for this prospective study (No. ChiCTR1900028230). We allocated the patients to two groups using block randomization (3D printing group, n = 20; conventional method group, n = 20). For the 3D printing group, 1:1 scaled pelvic models were created using 3D printing, and the plates were pre-contoured according to the pelvic models. The plates for the conventional method group were contoured during the operation without 3D printed pelvic models. The operation time, instrumentation time, time of intra-operative fluoroscopy, blood loss, number of times the approach was performed, blood transfusion, post-operative fracture reduction quality, hip joint function, and complications were recorded and compared between the two groups.Results:The operation and instrumentation times in the 3D printing group were significantly shorter (130.8 ± 29.2 min, t = −7.5, P < 0.001 and 32.1 ± 9.5 min, t = −6.5, P < 0.001, respectively) than those in the conventional method group. The amount of blood loss and blood transfusion in the 3D printing group were significantly lower (500 [400, 800] mL, Mann-Whitney U = 74.5, P < 0.001 and 0 [0,400] mL, Mann-Whitney U = 59.5, P < 0.001, respectively) than those in the conventional method group. The number of the approach performed in the 3D printing group was significantly smaller than that in the conventional method group (pararectus + Kocher-Langenbeck [K-L] approach rate: 35% vs. 85%; χ2 = 10.4, P < 0.05). The time of intra-operative fluoroscopy in the 3D printing group was significantly shorter than that in the conventional method group (4.2 ± 1.8 vs. 7.7 ± 2.6 s; t = −5.0, P < 0.001). The post-operative fracture reduction quality in the 3D printing group was significantly better than that in the conventional method group (good reduction rate: 80% vs. 30%; χ2 = 10.1, P < 0.05). The hip joint function (based on the Harris score 1 year after the operation) in the 3D printing group was significantly better than that in the conventional method group (excellent/good rate: 75% vs. 30%; χ2 = 8.1, P < 0.05). The complication was similar in both groups (5.0% vs. 25%; χ2 = 3.1, P = 0.182).Conclusions:The use of a pre-operative virtual simulation and 3D printing technology is a more effective method for treating both-column acetabular fractures. This method can shorten the operation and instrumentation times, reduce blood loss, blood transfusion and the time of intra-operative fluoroscopy, and improve the post-operative fracture reduction quality.Clinical trail registration:No.ChiCTR1900028230; http://www.chictr.org.cn

Despite 3D food printing being a nascent emerging technology in the food industry, it has a greater potential in fulfilling commercial and consumer needs. 3D printing has been forecasted to be revolutionizing the technology of the future. Various well-known 3D printing technologies are material extrusion, powder bed fusion, binder jetting, material jetting, vat polymerization, sheet lamination, and direct energy deposition. In context with food, not all the printing technologies are suitable for the printing process as food is a complex perishable commodity that often undergoes desired amount of pre- as well as postprocessing operations. Hence, this chapter envisages the major considerations of the food-printing process, material properties, and selectivity of materials that are suitable for specific food 3D printing technologies. Extrusion technology, selective sintering, inkjet printing, binder jetting, and bioprinting are the common 3D printing technologies used for the food-printing process that are distinct based on the mechanism of binding of printed layers. Understanding food printing technology is very crucial in terms of technical and design aspects for delivering 3D-printed food with enhanced levels of customization. Hence, the present chapter provides valuable insights into the working principles, binding mechanism, and system components of 3D food printing technologies. Certainly, this chapter helps in better understanding of food-printing process in upbringing the technology of 3D food printing to the next level. In addition, the future outcomes in designing multihead food printers and their efficiency in food production through 3D printing are also briefed.

Multimodal imaging plays a crucial role in evaluating suspected cardiac tumours. In recent years, three-dimensional (3D) printing technology has continued to advance such that image-based 3D-printed models have been incorporated into the auxiliary diagnosis and treatment of cardiac tumour diseases. The purpose of this review is to analyze the existing literature on the application of 3D printing in cardiac tumour surgery to examine the current status of the application of this technology. By searching PubMed, Cochrane, Scopus and Google Scholar, as well as other resource databases, a completed review of the available literature was performed. Effect sizes from published studies were investigated, and results are presented concerning the use of 3D surgical planning in the management of cardiac tumours. According to the reviewed literature, our study comes to the point that 3D printing is a valuable technique for planning surgery for cardiac tumours. As shown in the review report, Mucinous and sarcomatous tumours are the most commonly used tumours for 3D printing, magnetic resonance imaging (MRI) and computed tomography (CT) are the most commonly used technologies for preparing 3D printing models, the main printing technology is stereolithography, and the most used 3D modeling software is Mimics. The printing time and cost required for 3D printing are affected by factors such as the size of the type, complexity, the printed material and the 3D printing technology used. The reported research shows that 3D printing can understand the anatomy of complex tumour cases, virtual surgical simulation, as well as facilitate doctor-patient communication and clinical teaching. These results show that the development of 3D printing technology has brought more accurate and safe perioperative treatment options for patients with cardiac tumours. Therefore, 3D printing technology is expected to become a routine clinical diagnosis and treatment tool for cardiac tumours.