Assessing the dynamic extrusion-based 3D printing process for power-law fluid using numerical simulation

Effect of dielectric barrier discharge (DBD) plasma treatment on physicochemical and 3D printing properties of wheat starch

In recent years, the focus has shifted towards carbohydrate-based hydrogels and their eco-friendly preparation methods. This study involved an investigation into the treatment of wheat starch using dielectric barrier discharge (DBD) plasma technology over varying time gradients (0, 2, 5, 10, 15, and 20 min). The objective was to systematically examine the impact of different treatment durations on the physicochemical properties of wheat starch and the suitability of its gels for 3D printing. Morphology of wheat starch remained intact after DBD treatment. However, it led to a reduction in the amylose content, molecular weight, and crystallinity. This subsequently resulted in a decrease in the pasting temperature and viscosity. Moreover, the gels of the DBD-treated starch exhibited superior 3D printing performance. After a 2-min DBD treatment, the 3D printed samples of the wheat starch gel showed no significant improvements, as broken bars were evident on the surface of the 3D printed graphic, whereas DBD-20 showed better printing accuracy and surface structure, compared to the original starch without slumping. These results suggested that DBD technology holds potential for developing new starch-based gels with impressive 3D printing properties.

Polymers in 3D printing of external maxillofacial prostheses and in their retention systems

Maxillofacial defects, arising from trauma, oncological disease or congenital abnormalities, detrimentally affect daily life. Prosthetic repair offers the aesthetic and functional reconstruction with the help of materials mimicking natural tissues. 3D polymer printing enables the design of patient-specific prostheses with high structural complexity, as well as rapid and low-cost fabrication on-demand. However, 3D printing for prosthetics is still in the early stage of development and faces various challenges for widespread use. This is because the most suitable polymers for maxillofacial restoration are soft materials that do not have the required printability, mechanical strength of the printed parts, as well as functionality. This review focuses on the challenges and opportunities of 3D printing techniques for production of polymer maxillofacial prostheses using computer-aided design and modeling software. Review discusses the widely used polymers, as well as their blends and composites, which meet the most important assessment criteria, such as the physicochemical, biological, aesthetic properties and processability in 3D printing. In addition, strategies for improving the polymer properties, such as their printability, mechanical strength, and their ability to print multimaterial and architectural structures are highlighted. The current state of the prosthetic retention system is presented with a focus on actively used polymer adhesives and the recently implemented prosthesis-supporting osseointegrated implants, with an emphasis on their creation from 3D-printed polymers. The successful prosthetics is discussed in terms of the specificity of polymer materials at the restoration site. The approaches and technological prospects are also explored through the examples of the nasal, auricle and ocular prostheses, ranging from prototypes to end-use products.

Three-Dimensional Bioprinting of GelMA Hydrogels with Culture Medium: Balancing Printability, Rheology and Cell Viability for Tissue Regeneration

Three-dimensional extrusion bioprinting technology aims to become a fundamental tool for tissue regeneration using cell-loaded hydrogels. These biomaterials must have highly specific mechanical and biological properties that allow them to generate biosimilar structures by successive layering of material while maintaining cell viability. The rheological properties of hydrogels used as bioinks are critical to their printability. Correct printability of hydrogels allows the replication of biomimetic structures, which are of great use in medicine, tissue engineering and other fields of study that require the three-dimensional replication of different tissues. When bioprinting cell-loaded hydrogels, a small amount of culture medium can be added to ensure adequate survival, which can modify the rheological properties of the hydrogels. GelMA is a hydrogel used in bioprinting, with very interesting properties and rheological parameters that have been studied and defined for its basic formulation. However, the changes that occur in its rheological parameters and therefore in its printability, when it is mixed with the culture medium necessary to house the cells inside, are unknown. Therefore, in this work, a comparative study of GelMA 100% and GelMA in the proportions 3:1 (GelMA 75%) and 1:1 (GelMA 50%) with culture medium was carried out to determine the printability of the gel (using a device of our own invention), its main rheological parameters and its toxicity after the addition of the medium and to observe whether significant differences in cell viability occur. This raises the possibility of its use in regenerative medicine using a 3D extrusion bioprinter.

Effect of ferulic acid incorporation on structural, rheological, and digestive properties of hot-extrusion 3D-printed rice starch

The influence of ferulic acid (FA) on rice starch was investigated by incorporating it at various concentrations (0, 2.5, 5, 7.5, and 10 %, w/w, on dry starch basis) and subjecting the resulting composites to hot-extrusion 3D printing (HE-3DP) process. This study examined the effects of FA addition and HE-3DP on the structural, rheological, and physicochemical properties as well as the printability and digestibility of rice starch. The results indicated that adding 0-5 % FA had no significant effect; however, as the amount of FA increased, the printed product edges became less defined, the product's overall stability decreased, and it collapsed. The addition of FA reduced the elasticity and viscosity, making it easier to extrude the composite gel from the nozzle. Moreover, the crystallinity and short-range ordered structure of the HE-3D printed rice starch gel decreased with the addition of FA, resulting in a decrease in the yield stress and an increase in fluidity. Furthermore, the addition of FA reduced the digestibility of the HE-3D-printed rice starch. The findings of this study may be useful for the development of healthier modified starch products by adding bioactive substances and employing the 3D printing technology.

Customized development of 3D printed anthocyanin-phycocyanin polychromatic oral film via chondroitin sulfate homeostasis: A platform based on starch and κ-carrageenan

The development of oral film with diverse colors and customized nutrition is in line with the innovation of emerging food. In this study, polychromatic system was formed by regulating the ratio of phycocyanin (PC) to blueberry anthocyanin (BA). Further, chondroitin sulfate (CS) was utilized to achieve color-enhanced and homeostatic effects on PC-BA, and κ-carrageenan (KC) - starch complex was exploited as printing ink to construct oral film system. The color-enhanced effect of CS is mainly related to the complexation of sulfate groups, and the film-forming substrates are combined mainly through hydrogen bonding. In addition, the proportion of KC modulated the gel structure of printing ink, and affected 3D printability and physical properties of oral film. OF II (1.5 % KC content) had a uniform and dense network structure, with the most stable color and the highest BA retention (70.33 %) after 8 d of light exposure. Importantly, OF II had an excellent slow-release effect, and BA release rate was as high as 92.52 %. The optimized components can form polychromatic oral film with controllable color and structure, and provide new insights for the creation of sensory personalized and nutritionally customized food.

Effects of starch-fatty acid complexes with different fatty acid chain lengths and degrees of saturation on the rheological and 3D printing properties of corn starch

The effect of corn starch-fatty (CS-FA) complexes from varying carbon chain length and degree of unsaturation on the rheological and 3D printing properties of corn CS-FA complex gels. The CS-FA complexes with longer carbon chain lengths and lower saturation enhanced the ability of gels to bind water, promoting the formation of intermolecular hydrogen bonds. The CS-FA complexes inhibit retrogradation and increase the amount of bound water, thereby reducing the structural integrity and transforming the original skeleton structure into a flake-like structure. These changes in gel structure led to lower flow stress and storage modulus for CS-FA gels containing FAs with shorter carbon chain lengths and lower saturation, resulting in reduced "extrusion swelling" of the material and facilitating its extrusion. The decreased "extrusion swelling" of gel improved print line width and printing performance. The CS-FA complex gel-printed product with a 12-carbon chain FA has the greatest printing accuracy, thanks to its moderate G', flow stress, and viscosity. This study provides important information for the CS-FA complexes for the preparation of starch-based 3D printing materials.

The synergistic effect of κ-carrageenan and l-lysine on the 3D printability of yellow flesh peach gels: The importance of material elasticity in the printing process

This study investigated the effect of κ-carrageenan and l-lysine on the physical, chemical and textural properties of yellow flesh peaches and their suitability for 3D printing. The addition of κ-carrageenan and l-lysine was found to improve the apparent viscosity, elasticity, gel strength, and Young's modulus of the yellow flesh peach with κ-carrageenan and l-lysine gels (PCLG) and increase the minimum piston pressure required for 3D printing, thereby improving the printing performance. Optimum levels of κ-carrageenan and l-lysine (0.1 mmol/mL and 3.42 × 10-2 mmol/mL, respectively) were found to enhance mechanical strength, viscoelasticity and print fidelity. On the other hand, when the addition of κ-carrageenan is 0.1 mmol/mL, the addition of l-lysine causes an increase in the G0 value and a decrease in the η0 value of the PCLG according to Burger's model, indicating a transition from viscosity to elasticity and an increase in maximum extrusion force, while the apparent viscosity does not change significantly. The results of 3D printing showed that when the addition of κ-carrageenan and l-lysine reached 0.1 mmol/mL and 6.84 × 10-2 mmol/mL, respectively, the PCLG could not be smoothly extruded, indicating that elasticity also plays an important role during the extrusion process of the mixed gel.

Investigation of the mechanism of gelatin to enhance 3D printing accuracy of corn starch gel: From perspective of phase morphological changes

The study examined the impact of phase morphological transformations within the corn starch/gelatin system, induced by varying gelatin content, on its rheological properties and 3D printing performance. Gelatin addition inhibited the gelatinization and retrogradation of starch, which leaded to the transformation of continuous phase structure. The transition process from starch continuous phase to gelatin continuous phase promoted a thinner wall structure of the gel and loosed its dense network, resulting in reduced flow stress (τf) and storage modulus (G'). These changes improved the extrusion and "extrusion swelling" of gel ink materials, which made the print size of printed product closer to the set model. The formation of a gelatin continuous phase in the gel was helpful in increasing τf and G', resulting in enhanced support capacity of the printed product. This study presented meaningful information for the application of 3D printing to starch-gelatin complex foods.

Formulation and characterization of 3D printed chickpea protein isolate-mixed cereal dysphagia diet

The feasibility study of making 3D printed dysphagia diet was undertaken. A mixture of corn flour and buckwheat flour was used as the model cereal and chickpea protein isolate (CPI) was used as the model protein. Printing gels (inks) of the mixed cereal (control) and CPI-cereal mixture were produced by heating the formulations at 95 °C for 30 min and then cooling them to room temperature. The results showed that all the ink formulations containing CPI had higher apparent viscosity, preferable shear thinning behavior and shape supporting characteristics than that of the control. The cohesiveness and shape supporting ability of 10%CPI-cereal and 20%CPI-cereal formulations were poor and could not produce stable printing shape. The 30%CPI-cereal and 40%CPI-cereal formulations had suitable apparent viscosity, shear thinning behavior, storage modulus, yield stress and printing accuracy and the 3D printed products were stable. The control ink and 10%CPI-cereal ink had low cohesion and also could not pass the spoon tilt test. The 50%CPI-cereal formulation had high hardness and also could not pass the fork pressing test. The 30 % to 40 % CPI-cereal formulations were found to be suitable as dysphagia products as they could be classified as level 5 dysphagia diet.

Investigation of 3D printing of toddler foods with special shape and function based on fenugreek gum and flaxseed protein

The practicability of using corn and flaxseed protein as printing inks for manufacture of printed products specifically designed for toddlers as a dysphagia diet with high precision and special shapes with addition of fenugreek gum (FGG) was investigated. 3D printing was used to process grains and dysphagia-compatible food (corn) into a dietary product with attractive appearance which was also easy to swallow. Rheological measurements shown that appropriate amount of flaxseed protein (FP, 0-10 %) can reduce the stickiness and yield strength of printing material. Based on FTIR measurements, FP weakened the hydrogen bond strength of inks, but it was still an important gradient for the formation of the ink suitable for precision 3D printing. The TPA results shown that the addition of FP (0-10 %) remarkably reduced both the stickiness and hardness of the ink. These results shown that compared with the control group, materials with FGG additions possessed higher printing accuracy and self-supporting ability. Ink with 5 % FP content exhibited the best printability and swallowability, while ink with 10 % FP content had the lowest viscosity and hardness, but it was not suitable for 3D printing. 3D printing of objects printed using Ink-C (5%FP and 0.8 %FGG) showed high support characteristic and attractive appearance. According to the international IDDSI testing standards, Ink-C (5%FP and 0.8 %FGG), Ink-E (15%FP and 0.8 %FGG), and Ink-F (20%FP and 0.8 %FGG) were defined as level 5-minced and moist foods.

Modeling and Simulation of 3D Food Printing Systems-Scope, Advances, and Challenges

Food 3D printing is a computer-aided additive manufacturing technology that can transform foods into intricate customized forms. In the past decade, this field has phenomenally advanced and one pressing need is the development of strategies to support process optimization. Among different approaches, a range of modeling methods have been explored to simulate 3D printing processes. This review details the concepts of various modeling techniques considered for simulating 3D printing processes and their application range. Most modeling studies majorly focus on predicting the mechanical behavior of the material supply, modifying the internal texture of printed constructs, and assessing the post-printing stability. The approach can also be used to simulate the dynamics of 3D printing processes, in turn, assisting the design of 3D printers based on material composition, properties, and printing conditions. While most existing works are associated with extrusion-based 3D printing, this article presents scope for expanding avenues with prominent research and commercial interest. The article concludes with challenges and research needs, emphasizing opportunities for computational and data-driven dynamic simulation approaches for multi-faceted applications.

Optimizing Process Parameters of Direct Ink Writing for Dimensional Accuracy of Printed Layers

Direct ink writing (DIW) belongs to extrusion-based three-dimensional (3D) printing techniques. The success of DIW process depends on well-printable ink and optimized process parameters. After ink preparation, DIW process parameters considerably affect the parts' dimensional accuracy, and process parameters optimization for dimensional accuracy of printed layers is necessary for quality control of parts in DIW. In this study, DIW process parameters were identified and divided into two categories as the parameters for printing a line and the parameter from lines to a layer. Then, a two-step method was proposed for optimizing process parameters. Step 1 was to optimize process parameters for printing a line. In Step 1, continuity and uniformity of extruded filaments and printed rectangular objects were observed in screening experiments to determine printability windows for each process parameter. Then, interaction effect tests were conducted and degree of freedom for experiments was calculated followed by orthogonal array selection for the Taguchi design. Next, main experiments of line printing based on the Taguchi method were conducted. Signal-to-noise ratio calculations and analysis of variance were performed to find the optimal combination and evaluate the significance, respectively. Step 2 was to optimize the parameter from lines to a layer. In Step 2, the average width of the printed line under optimal condition was first measured. Then, single-factor tests of rectangular object printing were conducted to find the optimal parameter from lines to a layer. After these two steps, confirmation results were conducted to verify the reliability of the proposed method and the method robustness on other shapes and other materials; parameter adaptability in 3D parts printing from printed layers' analyses for the proposed method; and parameter adaptability in constructs fabricated as 100% infill or with porosities.

A Study of the Gelatin Low-Temperature Deposition Manufacturing Forming Process Based on Fluid Numerical Simulation

Low-temperature deposition manufacturing has attracted much attention as a novel printing method, bringing new opportunities and directions for the development of biological 3D printing and complex-shaped food printing. In this article, we investigated the rheological and printing properties of gelatin solution and conducted numerical simulation and experimental research on the low-temperature extrusion process of gelatin solution. The velocity, local shear rate, viscosity, and pressure distribution of the material in the extrusion process were calculated using Comsol software. The effects of the initial temperature, inlet velocity, and print head diameter of the material on the flow field distribution and printing quality were explored. The results show that: (1) the fluidity and mechanical properties of gelatin solution vary with its concentration; (2) the initial temperature of material, inlet velocity, and print head diameter all have varying degrees of influence on the distribution of the flow field; (3) the concentration change of the material mainly affects the pressure distribution in the flow channel; (4) the greater the inlet velocity, the greater the velocity and shear rate in the flow field and the higher the temperature of the material in the outlet section; and (5) the higher the initial temperature of the gel, the lower the viscosity in the flow field. This article is of great reference value for the low-temperature 3D printing of colloidal materials that are difficult to form at room temperature.

Self-Healing Injectable Hydrogels for Tissue Regeneration

Biomaterials with the ability to self-heal and recover their structural integrity offer many advantages for applications in biomedicine. The past decade has witnessed the rapid emergence of a new class of self-healing biomaterials commonly termed injectable, or printable in the context of 3D printing. These self-healing injectable biomaterials, mostly hydrogels and other soft condensed matter based on reversible chemistry, are able to temporarily fluidize under shear stress and subsequently recover their original mechanical properties. Self-healing injectable hydrogels offer distinct advantages compared to traditional biomaterials. Most notably, they can be administered in a locally targeted and minimally invasive manner through a narrow syringe without the need for invasive surgery. Their moldability allows for a patient-specific intervention and shows great prospects for personalized medicine. Injected hydrogels can facilitate tissue regeneration in multiple ways owing to their viscoelastic and diffusive nature, ranging from simple mechanical support, spatiotemporally controlled delivery of cells or therapeutics, to local recruitment and modulation of host cells to promote tissue regeneration. Consequently, self-healing injectable hydrogels have been at the forefront of many cutting-edge tissue regeneration strategies. This study provides a critical review of the current state of self-healing injectable hydrogels for tissue regeneration. As key challenges toward further maturation of this exciting research field, we identify (i) the trade-off between the self-healing and injectability of hydrogels vs their physical stability, (ii) the lack of consensus on rheological characterization and quantitative benchmarks for self-healing injectable hydrogels, particularly regarding the capillary flow in syringes, and (iii) practical limitations regarding translation toward therapeutically effective formulations for regeneration of specific tissues. Hence, here we (i) review chemical and physical design strategies for self-healing injectable hydrogels, (ii) provide a practical guide for their rheological analysis, and (iii) showcase their applicability for regeneration of various tissues and 3D printing of complex tissues and organoids.

Numerical Simulation and Experimental Study the Effects of Process Parameters on Filament Morphology and Mechanical Properties of FDM 3D Printed PLA/GNPs Nanocomposite

The selection of optimal process parameters has a decisive effect on the quality of 3D printing. In this work, the numerical and experimental methods were employed to investigate the FDM printing deposition process of PLA/GNPs nanocomposite. The effect of process parameters on cross-sectional morphology and dimension of the deposited filament, as well as the mechanical property of the FDM printed specimens were studied. The extrusion and the deposition process of the molten PLA/GNPs nanocomposite was simulated as a fluid flow by the paradigm of CFD, the effects of printing temperature and shear rate on thermal-physical properties, such as viscosity and surface tension, were considered in models. Under the assumptions of non-Newtonian fluid and creep laminar flow, the deposition flow was controlled by two key parameters: the nozzle temperature and the nozzle velocity. The numerical model was verified by experiments from four aspects of thickness, width, area, and compactness of the deposited PLA/GNPs nanocomposite filament cross-section. Both the numerical simulation and experiment results show that with the increase of nozzle temperature and nozzle velocity, the thickness, area, and compactness of the deposited filament decreases. While the width of deposited filament increased with the increase of nozzle temperature and decrease of nozzle velocity. The decrease in thickness and the increase in width caused by the change of process parameters reached 10.5% and 24.7%, respectively. The tensile strength of the printed PLA/GNPs specimen was about 61.8 MPa under the higher nozzle temperatures and velocity condition, an improvement of 18.6% compared to specimen with the tensile strength of 52.1 MPa under the lower nozzle temperatures and velocity condition. In addition, the experimental results indicated that under the low nozzle velocity and nozzle temperature condition, dimensional standard deviation of the printed specimens decreased by 52.2%, 62.7%, and 68.3% in X, Y, and Z direction, respectively.

Defects in 3D/4D food printing and their possible solutions: A comprehensive review

3D food printing has recently attracted significant attention, both from academic and industrial researchers, due to its ability to manufacture customized products in such terms as size, shape, texture, color, and nutrition to meet demands of individual consumers. 4D printing, which is a technique that allows evolution of various characteristics/properties of 3D printed objects over time through external stimulation, has also been gaining more attention. In order to produce defect-free printed objects via both 3D and 4D printing, it is necessary to first identify the causes of defects and then their mitigation strategies. Comprehensive review on these important issues is nevertheless missing. The purpose of this review is to investigate causes and characteristics of defects occurring during and/or after 3D food printing, with a focus on how different factors affect the printing accuracy. Various techniques that can potentially minimize or eliminate printing defects and produce high-quality 3D/4D printed food products without the need for time-consuming trial and error printing experiments are critically discussed. Guidelines to avoid defects to improve the efficiency of future 3D/4D printed food production are given.

Towards the Development of 3D-Printed Food: A Rheological and Mechanical Approach

Additive manufacturing, or 3D printing, has raised interest in many areas, such as the food industry. In food, 3D printing can be used to personalize nutrition and customize the sensorial characteristics of the final product. The rheological properties of the material are the main parameters that impact the 3D-printing process and are crucial to assuring the printability of formulations, although a clear relationship between these properties and printability has not been studied in depth. In addition, an understanding of the mechanical properties of 3D-printed food is crucial for consumer satisfaction, as they are related to the texture of food products. In 3D-printing technologies, each manufacturing parameter has an impact on the resulting mechanical properties; therefore, a thorough characterization of these parameters is necessary prior to the consumption of any 3D-printed food. This review focuses on the rheological and mechanical properties of printed food materials by exploring cutting-edge research working towards developing printed food for personalized nutrition.

Application of Computational Fluid Dynamics (CFD) in the Deposition Process and Printability Assessment of 3D Printing Using Rice Paste

Computational fluid dynamics (CFD) was utilized to investigate the deposition process and printability of rice paste. The rheological and preliminary printing studies showed that paste formed from rice to water ratio (100:80) is suitable for 3D printing (3DP). Controlling the ambient temperature at 47±5 °C also contributed to improving the printed sample’s structural stability. The viscoelastic simulation indicated that the nozzle diameter influenced the flow properties of the printed material. As the nozzle diameter decreased (1.2 mm to 0.8 mm), the die swell ratio increased (13.7 to 15.15%). The rise in the swell ratio was a result of the increasing pressure gradient at the nozzle exit (5.48×106 Pa to 1.53×107 Pa). The additive simulation showed that the nozzle diameter affected both the residual stress and overall deformation of the sample. CFD analysis, therefore, demonstrates a significant advantage in optimizing the operating conditions for printing rice paste.

Application of Computational Fluid Dynamics (CFD) Simulation for the Effective Design of Food 3D Printing (A Review)

The progress of food 3D printing (3DP) applications demands a full understanding of the printing behavior of food materials. Computational fluid dynamics (CFD) simulation can help determine the optimum processing conditions for food 3DP such as layer height, deposit thickness, volume flow rate, and nozzle shape and diameter under varied material properties. This paper mainly discusses the application of CFD simulation for three core processes associated with 3DP: (1) flow fields in the nozzle during the extrusion process; (2) die swelling of materials at the die (the exit part of the nozzle); and (3) the residual stress of printed products. The major achievements of CFD simulation in food 3DP with varied food materials are discussed in detail. In addition, the problems and potential solutions that modelers encountered when utilizing CFD in food 3DP were explored.

Formulation engineering of food systems for 3D-printing applications - A review

The efficient development of extrusion-based 3D-printing requires flexibility in both formulation- and process design. This task requires a fundamental understanding of the influence of material rheological properties on the extrusion process. Within this review, a qualitative toolbox for food extrusion is presented which provides guidelines for the formulation and engineering of extrusion processes in general and 3D-printing in particular. The toolbox is based on current knowledge of highly viscous food systems and the influence of individual components on the overall rheology. It includes the efficiency of particle packing, microstructure and the influence of shear rate, as well as the formation of self-supporting structures by gelation of the liquid phase and crowding of particles. Physical laws and semi-empirical equations are discussed to describe the rheology and relate relevant theory to the extrusion process. Practical information is presented, including examples of extrusion and 3D-printing of food and non-food systems. The qualitative extrusion toolbox provides a general framework for the emerging field of extrusion-based 3D-printing of food products. It can be used to identify which specific material and process parameters can be changed and how they may be altered to optimize the 3D-printing process. The general framework will assist researchers, as well as industry.

Trends in functional food development with three-dimensional (3D) food printing technology: prospects for value-added traditionally processed food products

One of the recent, innovative, and digital food revolutions gradually gaining acceptance is three-dimensional food printing (3DFP), an additive technique used to develop products, with the possibility of obtaining foods with complex geometries. Recent interest in this technology has opened the possibilities of complementing existing processes with 3DFP for better value addition. Fermentation and malting are age-long traditional food processes known to improve food value, functionality, and beneficial health constituents. Several studies have demonstrated the applicability of 3D printing to manufacture varieties of food constructs, especially cereal-based, from root and tubers, fruit and vegetables as well as milk and milk products, with potential for much more value-added products. This review discusses the extrusion-based 3D printing of foods and the major factors affecting the process development of successful edible 3D structures. Though some novel food products have emanated from 3DFP, considering the beneficial effects of traditional food processes, particularly fermentation and malting in food, concerted efforts should also be directed toward developing 3D products using substrates from these conventional techniques. Such experimental findings will significantly promote the availability of minimally processed, affordable, and convenient meals customized in complex geometric structures with enhanced functional and nutritional values.

Food Texture Design by 3D Printing: A Review

An important factor in consumers’ acceptability, beyond visual appearance and taste, is food texture. The elderly and people with dysphagia are more likely to present malnourishment due to visually and texturally unappealing food. Three-dimensional Printing is an additive manufacturing technology that can aid the food industry in developing novel and more complex food products and has the potential to produce tailored foods for specific needs. As a technology that builds food products layer by layer, 3D Printing can present a new methodology to design realistic food textures by the precise placement of texturing elements in the food, printing of multi-material products, and design of complex internal structures. This paper intends to review the existing work on 3D food printing and discuss the recent developments concerning food texture design. Advantages and limitations of 3D Printing in the food industry, the material-based printability and model-based texture, and the future trends in 3D Printing, including numerical simulations, incorporation of cooking technology to the printing, and 4D modifications are discussed. Key challenges for the mainstream adoption of 3D Printing are also elaborated on.

Novel evaluation technology for the demand characteristics of 3D food printing materials: a review

As a recently developed way of food manufacturing - 3D printing - is bringing about a revolution in the food industry. Rheological and mechanical properties of food material being printed are the determinants of their printability. Therefore, it is important to analyze the requirements of different 3D printing technologies on material properties and to evaluate the performance of the printed materials. In this review, the printing characteristics and classification of food materials are discussed. The four commonly used 3D printing techniques e.g. extrusion-based printing, selective sintering printing (SLS), binder jetting, and inkjet printing, are outlined along with suitable material characteristics required for each printing technique. Finally, recent technologies for evaluation of 3D printed products including low field nuclear magnetic resonance (LF-NMR), computer numerical simulation, applied reference material, morphological identification, and some novel instrumental analysis techniques are highlighted.

Past, Present, and Future of Soft-Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

Millions of people worldwide experience disfigurement due to cancers, congenital defects, or trauma, leading to significant psychological, social, and economic disadvantage. Prosthetics aim to reduce their suffering by restoring aesthetics and function using synthetic materials that mimic the characteristics of native tissue. In the 1900s, natural materials used for thousands of years in prosthetics were replaced by synthetic polymers bringing about significant improvements in fabrication and greater realism and utility. These traditional methods have now been disrupted by the advanced manufacturing revolution, radically changing the materials, methods, and nature of prosthetics. In this report, traditional synthetic polymers and advanced prosthetic materials and manufacturing techniques are discussed, including a focus on prosthetic material degradation. New manufacturing approaches and future technological developments are also discussed in the context of specific tissues requiring aesthetic restoration, such as ear, nose, face, eye, breast, and hand. As advanced manufacturing moves from research into clinical practice, prosthetics can begin new age to significantly improve the quality of life for those suffering tissue loss or disfigurement.