Biomimetic actuators with stimuli-responsiveness, adaptivity, and designability have attracted extensive attention. Recently, soft intelligent actuators based on stimuli-responsive materials have ...been gradually developed, but it is still challenging to achieve various shape manipulations of actuators through a simple 3D printing technology. In this paper, a 3D printing strategy based on magneto-active materials is developed to manufacture various biomimetic magnetic actuators, in which the new printable magnetic filament is composed of a thermoplastic rubber material and magnetic particles. The continuous shape transformation of magnetic actuators is further demonstrated to imitate the motion characteristic of creatures, including the predation behavior of octopus tentacles, the flying behavior of the butterfly, and the flower blooming behavior of the plant. Furthermore, the magnetic field-induced deformation of the biomimetic structure can be simulated by the finite element method, which can further guide the structural design of the actuators. This work proves that the biomimetic actuator based on soft magneto-active materials has the advantages of programmable integrated structure, rapid prototyping, remote noncontact actuation, and rapid magnetic response. As a result, this 3D printing method possesses broad application prospects in soft robotics and other fields.
In this article, we discuss the impacts of using 3D printing in education. Our primary goal is to evaluate the pedagogical impact of lessons utilizing 3D printing. We asked one hundred ninety ...students in four reference schools about the acceptability of existing 3D materials for teaching. Although the results show high attractiveness for the target group, it turned out that the available lessons primarily focus on the acquisition of technical skills and do not use the potential of education in other areas. We, therefore, proposed a concept for creating multidisciplinary teaching lessons that connect the technical part with other educational areas. We show the application of our concept in a newly developed lesson in biology, where we again evaluate its acceptance among the students. The results show that although the multidisciplinary lessons are more complex, they are still acceptable to the students, and, most importantly, they add significant educational value. Finally, we discuss the possibilities of incorporating 3D printing into the teaching curriculum. We also use a selected use case to illustrate the real-world problems we have encountered.
A rectum phantom is needed for the experiments for microwave sensor designed to sense lower abdomen. However, the rectum wall is thin which is challenging to be fabricated using the available recipes ...with desired electrical properties at the working frequency. In this paper, we propose a fabrication method for such a phantom using additive printed mold. The phantom has a thickness of 3 mm, which is close to that of rectal wall, and is hollow inside the wall allowing various fillers to perform experiments. For the fabrication, a multi-layered 3D printed polylactic acid (PLA) mold was designed to have the inter-layer space forming the shape of a rectum with 3-mm-thick wall. It is designed to ease demolding. Solution was poured into the space between layers, solidified, and demolded. To ensure reproductivity, the phantom’s fabrication protocol is optimized. A patch antenna connected to a vector network analyzer (VNA) is used to preliminarily measure the return loss under different filling levels of the phantom.
Background
To clinically evaluate 3D print‐formed implant process, using cranioplasty as a proof of concept, to examine its effectiveness and utility as a method of intraoperative implant ...fabrication.
Methods
Twelve patients had a 3D print‐formed template created for patient‐specific implant manufacture. Of these patients, 10 received intraoperatively formed polymethylmethacrylate cranioplasty implants between 2013 and 2019. The 3D print‐formed implant templates produced to manufacture these patient‐specific implants were generated using patient computed tomography scans and 3D printed using fused deposition modelling technology. Cosmetic and functional results were determined by participating surgeons, in conjunction with a patient questionnaire.
Results
The functional results and stability of the implants were deemed to be favourable by participating surgeons. Three of the 10 patients completed a post‐cranioplasty survey, all of whom judged their cosmetic results as good or excellent. At time of writing, the rate of surgical revision was zero and without clinically adverse outcomes.
Conclusions
3D print‐formed implants are an effective method of patient‐specific implant formation.
Ten patients received rapid 3D print‐formed cranioplasty implants, formed intraoperatively using polymethylmethacrylate between 2013 and 2019. The functional results and stability of the implants were deemed to be favourable by participating surgeons. 3D print‐formed implants are an effective method of patient‐specific implant formation.
The article presents the impact of individual settings of both 3D printers and software dedicated to the preparation of printouts. 3D printing methods are discussed. The individual methods and tools ...necessary for the implementation of 3D prints are described. Materials that are used in 3D printing technology are also discussed. In addition, the construction of printers on which the samples for the tests described in this work were prepared was discussed. The advantages and disadvantages of using individual slicers for 3D printing are presented. The obtained measurement results of samples made of polylactide (PLA) are presented. The work was summarized with final conclusions.
The lifetime and stability of reference electrodes is critical for the long-term reliability of electrochemical sensing technologies. In this work, we demonstrate that the operational lifespan of a ...reference electrode (RE) is heavily influenced by the length of the filling solution. A mathematical solution, based on 1D, Fickian diffusion between the RE filling solution and an infinite volume test solution, predicts that doubling the length of the filling solution channel will quadruple the lifespan of the RE. In comparison, halving the diffusion coefficient of the filling solution (e.g., by changing the material) only increases the RE lifetime by 20–25%. The quadratic dependence of the filling solution length on lifetime was experimentally observed by monitoring the open-circuit potentials of RE's composed of an Ag/AgCl couple and agar-gel filling solutions (agar + 1.0 M KCl) inside glass capillaries of different lengths. The 1 cm RE remained stable for 6 h, whereas a 10 cm RE was stable for approximately 18 days (430 h). Lastly, we demonstrate that 3D printed and CNC (computer numerical control) machined RE housings with long and narrow filling solution channels can be used to produce small REs with enhanced lifetimes. Reference electrodes prepared this way were low-cost, small, and more stable than a typical commercial reference electrode design. A 4 cm long, 3D printed RE housing with 3 mL of agar gel filling solution provided over 6 months of potential stability, outlasting a conventional RE design with double the amount of reference solution volume.
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3D printing allows industries to scale the development from rapid prototyping to mass production in an easier manner. However, a typical photopolymers resin for stereolithography 3D printing ...possesses lower mechanical properties which incapable to meet certain industrial requirements for high impact applications. Hence, 0.1 to 2.0 wt.% of graphene nanoplatelets (GnP) were incorporated into photo-curable polyurethane (PU) based resin through digital light processing (DLP) 3D printing to evaluate its reinforcement effect. FTIR spectrum proves that significant characteristics of PU were still dominant upon the addition of GnP, indicating there was no chemical interaction between PU and GnP. The interfacial adhesion and the homogeneity of GnP in PU matrix were investigated through morphological analysis and the strength and stiffness of the 3D-printed composites. Results shows, tensile strength and Young’s Modulus of the PU/1%GnP composite had an increment of 21% and 24%, respectively when compared to neat PU resin. However, further increment of GnP reduced the mechanical properties because of interruption in UV curing during printing, hence leading to interfacial voids and defects on the printed specimens.
Three-dimensional (3D) printing is a type of rapid prototyping technology known as “additive manufacturing”. To meet the stacking layer-by-layer requirements, the fresh materials should have ...sufficient strength to ensure there is no collapse and plastic flow during the printing process. In addition, the fresh materials should exhibit enough stiffness to resist the intolerable elastic deformation to ensure printing accuracy. Since most of the printed structures have large height-to-thickness ratios, stabilities of printed structures should be taken into account. In this study, we investigated the rheological properties of 3D printed recycled coarse aggregate concrete (RAC), including their rheological behaviors when subjected to shear, the growth pattern of yield stress and shear modulus with resting time. Based on rheological parameters, buildability of RAC with 0%, 50% and 100% replacement rates were evaluated from the perspectives of strength, deformation and stability. It was found that yield stress of RAC exponentially increased with resting time, while the shear modulus linearly increased with resting time. Furthermore, within the first 15 min of printing, RAC exhibited better buildability with increasing replacement rate, however, the open time was shortened. In addition, the relationship between flowability and yield stress of the printing material was evaluated. Compared to the linear relationship of mortar, the relationship between flowability and yield stress was found to be exponential in RAC.
•Yield stress of RAC exponentially increased with time, while the shear modulus linearly increased with time.•τ/ρg was successfully used as a buildability indicator to evaluate strength-based failure.•Within the first 15 min of printing, buildability of RAC increased with increasing RCA replacement rate.
Additive manufacturing techniques have demonstrated great potential in space manufacturing for long-duration human spaceflight and colonization on alien planets. Herein, we present the design and ...manufacturing of previously inaccessible complex ceramic components with high precision in a microgravity environment. The proposed approach is based on controlling the rheological properties of ceramic slurry in reduced-gravity. Briefly, HE-cellulose and carbomer 940 are added as thickening agents to transform the ceramic slurry into a ceramic paste(soft matter), which exhibits Bingham pseudoplastic behavior and is not sensitive to gravity variations during parabolic flight. Additionally, X-ray computed tomography (XCT) results reveal that the as-prepared alumina samples, 3D printed in a microgravity environment, render a higher density of 99.3% after sintering. The proposed route can be applied to fabricate complex-shaped ceramic components in space, enabling various possibilities of manufacturing structural and functional materials, including gradient materials, solid fuel cells, active insulation ceramic structures and piezoelectric sensors.
