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The purpose of this paper is to investigate the mechanical properties and porosity relationships in fused deposition modelling (FDM) fabricated porous structures.

Porous structures of numerous build architectures aimed at tissue engineering (TE) application were fabricated using the FDM. The employment of FDM to fabricate these non‐random constructs offers many advantages over conventional scaffold fabrication techniques as patient specific scaffolds with well‐defined architectures and controllable pore sizes can be fabricated accurately and rapidly. There exist several FDM parameters that one needs to specify during the scaffold fabrication process. These parameters, which can be interdependent and exhibit varying effects on scaffold properties, were identified and examined using the design of experiment (DOE) approach. Essentially, the effects of five FDM process parameters, namely air gap, raster width, build orientation, build layer and build profile, on the porosity and mechanical properties of acrylonitrile‐butadienene‐styrene (ABS) scaffold structures with three‐dimensional interconnectivity were investigated in two designed experiments. Statistical analyses of the data were performed and the respective factors that have significant influence on the porosity and mechanical properties of the scaffolds were identified. The relationship between scaffold's mechanical properties and porosity was thereafter established empirically.

Models of TE scaffolds of numerous build architectures were successfully fabricated using different parameter settings on the FDM. The DOE approach determined air gap and raster width as the most significant parameters in affecting the porosity and mechanical properties of the ABS scaffold structures. The relationship between scaffolds' mechanical properties and porosity was determined to be logarithmic, with the best mechanical properties observed in scaffolds of low porosity.

The paper highlights how the application FDM to tissue scaffold application can overcome most of the limitations encountered in the conventional techniques.

Successes in scaffold guided tissue engineering require scaffolds to have specific macroscopic geometries and internal architectures to provide the needed biological and biophysical functions. Freeform fabrication provides an effective process tool to manufacture many advanced scaffolds with designed properties. This paper reports our recent study on using a novel precision extruding deposition (PED) process technique to directly fabricate cellular poly‐ε_rm;‐caprolactone (PCL) scaffolds. Scaffolds with a controlled pore size of 250 μm and designed structural orientations were fabricated.

The 3 D bioprinting technology is used to prepare the tissue engineering scaffold with precise structures for the cell proliferation and differentiation.

According to the characteristics of the ideal tissue engineering scaffold, the microstructural design of the tissue engineering scaffold is carried out. The bioprinter is used to fabricate the tissue engineering scaffold with different structures and spacing sizes. Finally, the scaffold with good connectivity is achieved and used to cell PC12 culture.

The results show that the pore structure with the line spacing of 1 mm was the best for cell culture, and the survival rate of the inoculated cells PC12 is as high as 90%. The influence of the pore shape on the cell survival is not evidence.

This study shows that tissue engineering scaffolds prepared by 3 D bioprinting have graded structure for three-dimensional cell culture, which lays the foundation for the later detection of drug resistance.

Purpose – The purpose of this chapter is to understand how children expand independence within instructional interactions with their teachers. To do so, the authors re-examine how scaffolding is understood and applied.

Approach – First, the authors consult websites and literature used by teachers and academics to examine how the notion of scaffolding is employed and explained. The authors analyze the roles, the intentions, the means, and the timing of scaffolding as used in popular literature to explain and support instruction. The authors then entertain a conceptual shift: What would the scaffolding process look like if learning were conceived as agentive? With this in mind, the authors interrogate descriptions of the tenets and functions of scaffolding to consider the process in relief.

Findings – The authors track the consequences of the inversion of scaffolding onto the understandings of the gradual release of responsibility (GRR) model. Scaffolding is understood as sitting within a GRR model, wherein the learner gradually releases responsibility to a teacher at the point of need. Intersubjectivity remains a basis for the model. A Window for Examining Teaching–Learning Interactions is offered as a frame with which to analyze the theories of both the child and the teacher apparent within scaffolding interactions. An accurate teacher’s theory of the child’s current and changing theories is required for teaching to be honed to invite children to efficiently access personal and contextual resources and to seek assistance when needed within engaging tasks with scope.

Practical Implications – When children are positioned as initiators of their learning, they are able to use their vast repertoire of knowledge of the world, language/s and literacies, and familial, cultural, and community ways of knowing to create, interpret, and engage in tasks. In this agentive view, children are positioned as holding full responsibility at the onset of any task and gradually releasing their responsibility to access support, when needed. Within tasks that are sufficiently wide for engagement at varied entry points, learners are the catalyst of the functions that were formerly initiated by teachers. Teachers invite children to access personal and contextual resources and to seek assistance, as needed, through additional external, contextual resources. This inverted model of scaffolding, that is child-directed rather than teacher-initiated, requires teachers to go beyond theories of teaching and learning and develop a theory of an individual child.

The purpose of this study to investigate the organized porous network zinc (OPNZ) scaffolds. Their mechanical characteristics, surface roughness and fracture mechanism were assessed in relation to their structural properties. The prospects of fused deposition modeling (FDM) for printing metal scaffolds via rapid tooling have also been studied.

Zn scaffolds with different pore and strut sizes were manufactured via the rapid tooling method. This method is a multistep process that begins with the 3D printing of a polymer template. Later, a paraffin template was obtained from the prepared polymer template. Finally, this paraffin template was used to fabricate the Zn scaffold using microwave sintering. The characterization of prepared Zn samples involved structural characterization, microstructural study, surface roughness testing and compression testing. Moreover, based on the Gibson–Ashby model analysis, the model equations’ constant values were evaluated, which can help in predicting the mechanical properties of Zn scaffolds.

The scanning electron microscopy study confirmed that the fabricated sample pores were open and interconnected. The X-ray diffraction analysis revealed that the Zn scaffold contained hexagonal closed-packed Zn peaks related to the a-Zn phase, validating that scaffolds were free from contamination and impurity. The range for ultimate compressive strength, compressive modulus and plateau stresses for Zn samples were found to be 6.75–39 MPa, 0.14–3.51 GPa and 1.85–12.6 MPa by adjusting their porosity, which are comparable with the cancellous bones. The average roughness value for the Zn scaffolds was found to be 1.86 µm.

This research work can widen the scope for extrusion-based FDM printers for fabricating biocompatible and biodegradable metal Zn scaffolds. This study also revealed the effects of scaffold structural properties like porosity, pore and strut size effect on their mechanical characteristics in view of tissue engineering applications.

The purpose of this paper is to fabricate the scaffolds with different pore architectures using additive manufacturing and analyze its mechanical and biological properties for bone tissue engineering applications.

The polylactic acid (PLA)/composite filament were fabricated through single screw extrusion and scaffolds were printed with four different pore architectures, i.e. circle, square, triangle and parallelogram with fused deposition modelling. Afterwards, scaffolds were coated with hydroxyapatite (HA) using dip coating technique. Various physical and thermo-mechanical tests have been conducted to confirm the feasibility. Furthermore, the biological tests were conducted with MG63 fibroblast cell lines to investigate the biocompatibility of the developed scaffolds.

The scaffolds were successfully printed with different pore architectures. The pore size of the scaffolds was found to be nearly 1,500 µm, and porosity varied between 53% and 63%. The fabricated circular pore architecture resulted in highest average compression strength of 13.7 MPa and modulus of 525 MPa. The characterizations showed the fidelity of the work. After seven days of cell culture, it was observed that the developed composites were non-toxic and supported cellular activities. The coating of HA made the scaffolds bioactive, showing higher wettability, degradation and high cellular responses.

The research attempts highlight the development of novel biodegradable and biocompatible polymer (PLA)/bioactive ceramic (Al₂O₃) composite for additive manufacturing with application in the tissue engineering field.

To advance the learning of professional practices in teacher education and medical education, this conceptual paper aims to introduce the idea of representational scaffolding for digital simulations in higher education.

This study outlines the ideas of core practices in two important fields of higher education, namely, teacher and medical education. To facilitate future professionals’ learning of relevant practices, using digital simulations for the approximation of practice offers multiple options for selecting and adjusting representations of practice situations. Adjusting the demands of the learning task in simulations by selecting and modifying representations of practice to match relevant learner characteristics can be characterized as representational scaffolding. Building on research on problem-solving and scientific reasoning, this article identifies leverage points for employing representational scaffolding.

The four suggested sets of representational scaffolds that target relevant features of practice situations in simulations are: informational complexity, typicality, required agency and situation dynamics. Representational scaffolds might be implemented in a strategy for approximating practice that involves the media design, sequencing and adaptation of representational scaffolding.

The outlined conceptualization of representational scaffolding can systematize the design and adaptation of digital simulations in higher education and might contribute to the advancement of future professionals’ learning to further engage in professional practices. This conceptual paper offers a necessary foundation and terminology for approaching related future research.

This paper aims to present the development of an electrospinning-based rapid prototyping (ESRP) technique for the fabrication of patterned scaffolds from fine fiber.

This ESRP technique unifies rapid prototyping (RP) and electrospinning to obtain the ability of RP to create a controllable pattern and of electrospinning to create a continuous fine fiber. The technique follows RP process of fused deposition modeling, but instead of using extrusion process for fiber creation, electrospinning is applied to generate a continuous fiber from a liquid solution. A machine prototype has been constructed and used in the experiments to evaluate the technique.

Three different lay-down patterns: 0°/90°, 45°/135° and 45° twists were used in the experiments. According to the experimental results, stacks of patterned layers could be created with the ESRP technique, and the fabrication process was repeatable and reproducible. However, the existing machine vibration influenced the fiber size and the ability to control straightness and gap size. Also, incomplete solidification of the fibers prior to being deposited obstructed the control of layer thickness. Improvement on vibration suppression and fiber solidification will strengthen the capability of this ESRP technique.

This research is currently limited to the introduction of the ESRP technique, to the development of the machine prototype, to the demonstration of its capability and to the evaluation of the structural properties of the fabricated patterned scaffolds. Further studies are required for better control of the patterned scaffolds and for investigation of mechanical and biological properties.

This unification of the two processes allows not only the fabrication of controllable patterned scaffolds but also the fabrication of both woven and non-woven layers of fibers to be done on one machine.

The purpose of this paper is to review the current status of additive manufacturing (AM) used for tissue engineering (TE) scaffold. AM processes are identified as an effective method for fabricating geometrically complex objects directly from computer models or three-dimensional digital representations. The use of AM technologies in the field of TE has grown rapidly in the past 10 years.

The processes, materials, precision, applications of different AM technologies and their modified versions used for TE scaffold are presented. Additionally, future directions of AM used for TE scaffold are also discussed.

There are two principal routes for the fabrication of scaffolds by AM: direct and indirect routes. According to the working principle, the AM technologies used for TE scaffold can be generally classified into: laser-based; nozzle-based; and hybrid. Although a number of materials and fabrication techniques have been developed, each AM technique is a process based on the unique property of the raw materials applied. The fabrication of TE scaffolds faces a variety of challenges, such as expanding the range of materials, improving precision and adapting to complex scaffold structures.

This review presents the latest research regarding AM used for TE scaffold. The information available in this paper helps researchers, scholars and graduate students to get a quick overview on the recent research of AM used for TE scaffold and identify new research directions for AM in TE.

Musculoskeletal conditions are a major health concern in the USA because of a large aging population and increased occurrence of sport‐related injuries. Bone tissue engineering may offer a less painful alternative to traditional bone grafts with lower risk of infection. The purpose of this paper is to present a novel porogen‐based fabrication system for tissue engineering scaffolds using sucrose (C₁₂H₂₂O₁₁) as the porogen building material.

A new solid freeform fabrication system has been developed and tested, which uses pressurized extrusion to print highly biocompatible and water soluble sucrose bone scaffold porogens (or negtives). Polycaprolactone (PCL) scaffolds are manufactured by injecting molten polymer into the porogens, and the porogens are subsequently dissolved with water. The resultant scaffolds demonstrate the defined porous structure designed into the sucrose porogen manufacturing computer‐aided design model.

To optimize the porogen manufacturing process, the viscosity of sucrose mixtures is measured. Design of experiments is used to plan and analyze the relationships between the porogen characteristics and the process parameters. Reservoir pressure and print head speed are identified as the dominant factors affecting sucrose flow rate and porogen strut diameter, respectively. The biocompatibility of the new system is assessed by in vitro cell culture testing. Endothelial hybridoma cells (EAhy 926) and osteoblasts (7F2) seeded on the fabricated PCL scaffolds adhered to the scaffold and proliferated over four to six days. Epifluorescence and scanning electron microscopy images reveal cell spreading and multiple layers of cells on the scaffold surface. The results demonstrated the potential of the structured sucrose porogen‐based fabrication method in manufacturing bone tissue scaffolds.

This paper describes the first time use of biomaterials‐sucrose to make scaffold porogens and how an injection molded biopolymer scaffold can then be received.