Deposition Modeling 3D Printing Research Articles

Material requirements for printing cookie dough using a fused deposition modeling 3D printer.

This study examined the requirements for using flour-based formulations in fused deposition modeling (FDM) of cone-shaped cookie dough. By considering the requirements of fidelity, shape retention, and extrudability, the rheological and mechanical parameters, which resulted in high printability (93.88‒96.49%) and dimensional stability (96.36‒97.15%), for formulations containing soft wheat flour, granulated sugar, water, and olive oil were determined to be: storage modulus (G') of 7165‒12,590Pa, loss modulus (G″) of 4161‒8297Pa, shear modulus of 6613‒12,804Pa, yield stress (τ0) of 50.22‒72.80Pa, phase angle of 30.28‒33.52°, apparent viscosity of 181.25‒230.20Pa·s, and hardness of 0.65-0.91N. When olive oil and water were replaced with butter and egg, the formulations demonstrated higher values of G', G″, shear modulus, τ0, and hardness; a smaller phase angle; and a wider range of apparent viscosity. These results provide quantitative information for developing cookie dough formulations suitable for 3D printing by FDM.

Aversion liquid-filled drug releasing capsule (3D-RECAL): A novel technology for the development of immediate release abuse deterrent formulations using a fused deposition modelling (FDM) 3D printer

COVID19 has caused a significant socioeconomic burden worldwide. Opioid crisis was further intensified with the increasing number of opioid overdose/misuse related deaths in last two years. Abusers have adopted newer/efficient methods for manipulating and abusing commercial opioid formulations. Food and Drug Administration (FDA) has been strategizing tirelessly to prevent misuse/abuse of prescription opioids. One of the strategies is to develop an abuse deterrent formulation (ADF). The current study aims to develop a novel 3D printed drug-releasing capsule shell filled with an aversion liquid (3D-RECAL). Primarily, metformin hydrochloride (MT, model drug) loaded printable filaments of polyvinyl alcohol was prepared using hot melt extrusion. Following extrusion, a 3D printed capsule shell was designed and fabricated using a single nozzle fuse deposition modelling 3D printer. An aversion liquid to be filled in 3D-RECAL capsules was prepared by combining sudan black and sodium polyacrylamide starch in oil base. Mechanical analysis of extruded filaments suggested that the filaments with 20%w/w MT had a higher mechanical strength compared to other drug loadings. Instantaneous gelling and large black non-snortable particles were formed during solvent extraction and physical manipulation studies, respectively. Due to the drug being embedded in the capsule shell, MT release was immediately started with >85% of MT release within 45 mins in 0.1 N HCl. Due to the everlasting need for the newer efficient ADF technologies, 3D-RECAL can be a step in the right direction towards saving lives, providing safe and effective measures to deterring abusers.

Hybrid machine-learning and finite-element design for flexible metamaterial wings

Insect wings are formed by intricate combinations of flexible membranes and rigid veins; such a structure enables excellent flight performance, adaptability to aerodynamic forces, and biological functions. Comprehensive understanding of the interplay between wing patterning and flight dynamics has however not been achieved yet due to enormous variability of natural patterns and the extreme complexity of the modeling wing-air interactions. Therefore, the design of a pattern for artificial flexible wings is challenging. In contrast to other studies mimicking biological patterns of insect wings, we propose usage of metamaterials principles to enable controllable dynamics, and machine-learning techniques to solve a related multi-parameter design optimization problem. We demonstrate the advantages of this hybrid approach by finding practical patterns with improved target property – enhanced lift. The obtained designs were manufactured by means of a low-cost fused deposition modeling (FDM) 3D-printer from a single commercially available thermoplastic polyurethane (TPU) and revealed the required balance between the rigidity of metamaterial “veins” and the flexibility of the wing base. Extensions of our approach to other designs or analyses of other moving structures offer straightforward benefits in tackling a wide range of computationally complex aerodynamic and vibroacoustic problems.

The Development of Gastro-Retentive Tablet using Hot Melt Extrusion and 3D Printing Technology

In this study, a three-dimensional (3D) printed gastro-retentive tablet (3DPGRT) containing sarpogrelate HCl was prepared by changing the amount of the polymers (Eudagit？？L100-55 (EuL), pectin, and polyethylene oxide (PEO)) by coupling hot melt extrusion (HME) and 3D printing technology. The study aims to evaluate the swelling and dissolution behavior for application as a gastro-retentive drug delivery system and optimize the formulation of 3DPGRT based on the design of experiment using central composite design. The flexibility and elasticity of the extruded filaments were affected by EuL, pectin, and PEO, which either showed a linear or quadratic pattern. 3DPGRT containing sarpogrelate HCl was fabricated successfully by coupling HME and a fused deposition modeling 3D printer without being affected by EuL, pectin, and PEO. Compatibility studies of the drug-excipient through FT-IR and DSC revealed the absence of any interaction between the drug and polymers. The developed 3DPGRT possessed the ability to float over 10 h. The dissolution rate of sarpogrelate HCl was significantly affected by the interaction between EuL and pectin. The results confirmed that the mechanism of drug release of 3DPGRT is caused by a combination of non-Fickian diffusion and dilatation, which fits well with the Higuchi and Korsmeyer-Peppas model. The optimized formulation have been obtained by numerical optimization, which yielded excellent floating properties and a desirable swelling ratio with controlled drug release. This study showed the application of quality by design in the formulation development of 3DPGRT coupled with HME, which can be used to control the swelling characteristics and dissolution behavior through the interaction between EuL and pectin.

Izod impact and hardness properties of 3D printed lightweight CF-reinforced PLA composites using design of experiment

3D printing plays an excellent role in the fabrication of customized parts for a variety of industrial sectors, but the printing parameters have a major influence on the performance of the printed parts. Therefore, this study aims to investigate a set of optimized parameters to manufacture cost-effective lightweight parts having enhanced impact strength and hardness properties. To accomplish this, carbon fiber (CF) reinforced polylactic acid (PLA) was used to fabricate Izod test specimens as per ASTM D256 standard with the help of a fused deposition modeling (FDM) 3D printer. An L9 array of Taguchi design of experiment was utilized for experimental runs and the performance of fabricated specimens was tested using an impact tester and digital Shore D durometer. It was observed that the Izod impact strength is highly influenced by the print speed and infill density. The maximum impact strength (113.84 J/m) was observed for the grid-type infill pattern at the highest nozzle temperature, median print speed, and median infill density. The maximum hardness observed as 79.6 (Shore D) is 37.95% higher than pure PLA due to the presence of fiber. The parameters for cost-effective lightweight parts with maximized impact strength and hardness properties were found at nozzle temperature 240 °C, print speed 120 mm/s, and infill density 50% with the grid type infill pattern. Differential scanning calorimeter (DSC) thermograms indicated thatthe crystallinity of CF-reinforced PLA is significantly altered during the 3D printing process due to the fast heating/cooling of the filament. The present study would provide a piece of extensive knowledge to designers and professionals working in this area for making proper judgments.

Comparison of axon extension: PTFE versus PLA formed by a 3D printer

Three-dimensional (3D) printers mainly create 3D objects by stacking thin layers of material. The effect of the tools created using the fused deposition modeling (FDM) 3D printer on nerve cells remains unclear. In this study, the effects of polytetrafluoroethylene (PTFE) models and two different types of polylactic acid (PLA) models (white or natural), were created using the FDM 3D printer on axon extension were compared using the Campenot chamber. Neurons were isolated from the dorsal root ganglia and added to the central compartment of the Campenot chambers after isolation, processing, and culturing. On day 7, after the initiation of the culture, the difference of the axon extensions to the side compartments of each group was confirmed. We also compared the pH and the amount of leakage when each of these chambers was used. The PLA was associated with a shorter axon extension than the PTFE (white p = 0.0078, natural p = 0.00391). No difference in the pH was observed (p = 0.347), but there was a significant difference on multiple group comparison (p = 0.0231) in the amount of leakage of the medium. PTFE was found to be a more suitable material for culturing attachments.

Antibacterial activity of ciprofloxacin-impregnated 3D-printed polylactic acid discs: an in vitro study.

Three-dimensional (3D) printing technology allows incorporation of various substances including antibiotics into different structures. This study aimed to evaluate the antibacterial activity of ciprofloxacin-impregnated 3D discs against Escherichia coli. Polylactic acid pellets were coated with ciprofloxacin at 1% and 2% concentrations, then filaments were produced from these pellets, and antibiotic-containing discs were obtained using fused deposition modeling 3D printers. The working temperatures during filament extrusion and 3D printing processes were 200 °C and 215 °C, respectively. Therefore, in order to test the thermal stability of ciprofloxacin during these processes, the antibiotic was exposed to 200 °C and 215 °C in an oven, and then tested against E. coli. Following this, efficiencies of antibiotic-coated pellets, filaments and discs against E. coli were determined by diffusion tests. Ciprofloxacin heated at 200 °C and 215 °C was stable and retained its antibacterial activity. Pellets, filaments and discs coated with 1% or 2% concentration of ciprofloxacin produced inhibition zones in the culture plates. Increasing ciprofloxacin concentration did not significantly affect the diameter of inhibition zones (p > 0.05). Ciprofloxacin-containing polylactic acid pellets produced significantly larger inhibition zones than those of filaments and discs (p < 0.0001). The difference in zone diameters around ciprofloxacin-containing filaments and discs was not statistically significant (p > 0.05). Ciprofloxacin-coated polylactic acid-based 3D discs displayed antibacterial activity against E. coli. This suggests that, various polylactic acid-based ciprofloxacin-containing 3D products can be obtained and evaluated for antibacterial activity in future studies.

Fiber Thickness and Porosity Control in a Biopolymer Scaffold 3D Printed through a Converted Commercial FDM Device.

3D printing has opened exciting new opportunities for the in vitro fabrication of biocompatible hybrid pseudo-tissues. Technologies based on additive manufacturing herald a near future when patients will receive therapies delivering functional tissue substitutes for the repair of their musculoskeletal tissue defects. In particular, bone tissue engineering (BTE) might extensively benefit from such an approach. However, designing an optimal 3D scaffold with adequate stiffness and biodegradability properties also guaranteeing the correct cell adhesion, proliferation, and differentiation, is still a challenge. The aim of this work was the rewiring of a commercial fuse deposition modeling (FDM) 3D printer into a 3D bioplotter, aiming at obtaining scaffold fiber thickness and porosity control during its manufacturing. Although it is well-established that FDM is a fast and low-price technology, the high temperatures required for printing lead to limitations in the biomaterials that can be used. In our hands, modifying the printing head of the FDM device with a custom-made holder has allowed to print hydrogels commonly used for embedding living cells. The results highlight a good resolution, reproducibility and repeatability of alginate/gelatin scaffolds obtained via our custom 3D bioplotter prototype, showing a viable strategy to equip a small-medium laboratory with an instrument for manufacturing good-quality 3D scaffolds for cell culture and tissue engineering applications.

ON THE SURFACE ROUGHNESS OF 3D PRINTED PARTS WITH FDM BY A LOW-BUDGET COMMERCIAL PRINTER

As additive manufacturing machines price is decreasing, while, at the same time, the expertise in the relevant field is rising, it is essential to test and evaluate the low-budget machines that are available for commercial use. Whilst low-budget machines are widely utilized for rapid prototyping and experimentation, they are not capable of producing parts with high surface quality and achieve high levels of repeatability due to low quality hardware and not optimized software. Having said that, the main aim of the current study is to experiment with a low budget Fused Deposition Modeling (FDM) 3D-Printer, and evaluate the surface roughness of the printed parts in respect to the angle from the print plate. Polylactic Acid (PLA) was chosen as filament material, while the printed parts surface roughness was measured according to the ISO ASTM 52902-2021 standard. The surface roughness was estimated in terms of the Ra and Rz values, while a statistical analysis was implemented in order some interesting conclusions to be deduced regarding the correlation between part orientation and surface quality.

A trial to convert a polymer FDM 3D printer to handle clay materials

The research aims to show the ability to convert the Fused Deposition Modeling 3D printer to be compatible with the clay mixture after modifying the structure, setting up Cura software, and changing the print head technology. This solution provides research teams and scientists with opportunities in several ways (manufacture patch antenna substrate, dielectric automobile sensors, and ceramic dielectric aerospace technology). Additive manufacturing allows the production of many intricate shapes with ceramics, which is difficult with a traditional method. This paper used WASP ceramic slurry as raw material for Liquid Deposition Modeling (LDM) of various samples using the Archimedes screw and air pressure dispensing technique (a two-step process). LDM is a low-cost and straightforward technology appropriate for the clay prototype scale. Different clay-built shapes have been produced with water-to-clay ratios ranging from 0.57 to 0.69. The effect of the nozzle size in printing experiment tests is demonstrated. The experiment tested the print head (extruder) mechanism, the properties of the materials suitable for the putty, and how the wet slurry material is extruded from the nozzle. The optimum air pressure and slicing configuration for efficient printing are provided. Samples were stress-tested after they were dried for 24 h at average laboratory temperature and then exposed to 1000^circ for 1 h.

Optimal design of a novel graded auxetic honeycomb core for sandwich beams under bending using digital image correlation (DIC)

The present paper proposed an auxetic honeycomb for sandwich structure with a novel graded design. The auxetic graded design is achieved by a variation of honeycomb cell angle through the core thickness. This variation affects the other geometric parameters and the mechanical properties. The enhanced specific bending properties of the sandwich structure are obtained by using Taguchi design of experiments (DOEs) by optimizing the cell wall thickness, cell aspect ratio, and cell angle gradation. The specimens of the DOEs are fabricated using fused deposition modeling (FDM) 3D printer. The strain fields in the core and the damage evolution under real-time flexural loading conditions are assessed by performing digital image correlation (DIC) analysis. The experimental and DIC analysis results are validated by the three-dimensional finite element analysis with consideration of elastoplastic behavior and crack growth possibility. The results indicate that the reduction of the cell wall thickness to length ratio increases the bending failure stress and specific absorbed energy by 35% and 45.8%, respectively, and the optimum cell angle gradation improves the flexural modulus to density ratio with an increase of 18.9%.

3D Printing of Abdominal Immobilization Masks for Therapeutics: Dosimetric, Mechanical and Financial Analysis.

Molding immobilization masks is a time-consuming process, strongly dependent on the healthcare professional, and potentially uncomfortable for the patient. Thus, an alternative sustainable automated production process is proposed for abdominal masks, using fused deposition modelling (FDM) 3D printing with polylactic acid (PLA). Radiological properties of PLA were evaluated by submitting a set of PLA plates to photon beam radiation, while estimations of their mechanical characteristics were assessed through numerical simulation. Based on the obtained results, the abdominal mask was 3D printed and process costs and times were analyzed. The plates revealed dose transmissions similar to the conventional mask at all energies, and mechanical deformation guarantees the required immobilization, with a 66% final cost reduction. PLA proved to be an excellent material for this purpose. Despite the increase in labour costs, a significant reduction in material costs is observed with the proposed process. However, the time results are not favorable, mainly due to the printing technique used in this study.

Lignocellulose nanofiber/polylactic acid (LCNF/PLA) composite with internal lignin for enhanced performance as 3D printable filament

The use of lignocellulose materials to prepare reinforced composites for 3D printing is promising. In this study, lignocellulose nanofibers (LCNFs) with different lignin contents (0.2–8.5%) were prepared and compounded with polylactic acid (PLA) for fabricating a 3D printable filament. The internal lignin of LCNFs served as an adhesive for improving the interfacial compatibility of LCNF/PLA composites. Alkali lignin (AL), as an external lignin, was used as a control sample. LCNFs, with a high yield of 85%, a diameter of less than 100 nm, and a length of several microns, were prepared by the swelling of glycerol and 0.64% (w/w) sulfuric acid and colloid mill grinding. Complexation of cellulose nanofiber (CNF) and LCNF with PLA can enhance the mechanical strength of PLA composites. Specifically, the flexural strength of the CNF/PLA composite was increased from 92.7 MPa to 151.2 MPa by combining 10% CNF (without lignin) with PLA. The flexural strength of LCNF/PLA composite with internal lignin content of 3.7% (0.37% of the total mass) was increased from 151.2 MPa to 234.5 MPa, which is 153.0% higher than that of pure PLA. However, external AL had an adverse influence on the mechanical strength of the AL/CNF/PLA composites. In addition, the 3D printable filament prepared using the LCNF/PLA composite exhibited good thermal stability, which was suitable for common fused deposition modeling (FDM) 3D printers. Various 3D printing materials, such as cake, egg, ball, bowl, dumbbell and strip shaped products, were designed and prepared by LCNF/PLA composites.

Low-Cost 3D Printer Drawn Optical Microfibers for Smartphone Colorimetric Detection.

A fused deposition modeling (FDM) 3D printer extruder was utilized as a micro-furnace draw tower for the direct fabrication of low-cost optical fibers. An air-clad multimode microfiber was drawn from optically transparent polyethylene terephthalate glycol (PETG) filament. A custom-made spooling collection allows for an automatic variation of fiber diameter between ϕ ∼ 72 to 397 μm by tuning the drawing speed. Microstructure imaging as well as the 3D beam profiling of the transmitted beam in the orthogonal axes was used to show good quality, functioning microfiber fabrication with uniform diameter and identical beam profiles for orthogonal axes. The drawn microfiber was used to demonstrate budget smartphone colorimetric-based absorption measurement to detect the degree of adulteration of olive oils with soybean oil.

A 3D Printed Modular Soft Gripper Integrated With Metamaterials for Conformal Grasping.

A single universal robotic gripper with the capacity to fulfill a wide variety of gripping and grasping tasks has always been desirable. A three-dimensional (3D) printed modular soft gripper with highly conformal soft fingers that are composed of positive pressure soft pneumatic actuators along with a mechanical metamaterial was developed. The fingers of the soft gripper along with the mechanical metamaterial, which integrates a soft auxetic structure and compliant ribs, was 3D printed in a single step, without requiring support material and postprocessing, using a low-cost and open-source fused deposition modeling (FDM) 3D printer that employs a commercially available thermoplastic poly (urethane) (TPU). The soft fingers of the gripper were optimized using finite element modeling (FEM). The FE simulations accurately predicted the behavior and performance of the fingers in terms of deformation and tip force. Also, FEM was used to predict the contact behavior of the mechanical metamaterial to prove that it highly decreases the contact pressure by increasing the contact area between the soft fingers and the grasped objects and thus proving its effectiveness in enhancing the grasping performance of the gripper. The contact pressure can be decreased by up to 8.5 times with the implementation of the mechanical metamaterial. The configuration of the highly conformal gripper can be easily modulated by changing the number of fingers attached to its base to tailor it for specific manipulation tasks. Two-dimensional (2D) and 3D grasping experiments were conducted to assess the grasping performance of the soft modular gripper and to prove that the inclusion of the metamaterial increases its conformability and reduces the out-of-plane deformations of the soft monolithic fingers upon grasping different objects and consequently, resulting in the gripper in three different configurations including two, three and four-finger configurations successfully grasping a wide variety of objects.

Multiscale simulation on nonlinear mechanical properties of 3D printed cellulose composites

Polypropylene (PP), a major thermoplastic resin, is widely used in compression molding and injection molding due to its excellent mechanical properties and recyclability. In general, talc, an inorganic mineral product, is widely used as a reinforcing filler in PP. Talc has excellent chemical stability, electrical insulation, and affinity with organic materials. However, PP has a high coefficient of linear expansion, making it difficult to use with the fused deposition modeling 3D printers that have become increasingly popular in recent years because of warping of the printed structures. On the other hand, cellulose nanofiber (CNF) is a plant fiber that has been degraded to the nanoscale and is expected to be used as a reinforcing filler for composite materials because of its superior specific stiffness and specific strength. It is expected to reduce environmental impact compared to conventional reinforcing fillers due to its reduced CO2 emissions and high recyclability. In addition, the high aspect ratio and low coefficient of linear expansion of CNF can be expected to reduce thermal deformation of composite materials. In this study, the mechanical properties of PP composites reinforced by talc and CNF fillers were tested by multiscale finite element analysis. The contents of talc and CNF were changed, and the effects of adding each were clarified.

Optimization of FDM 3D Printing Process Parameters on ABS based Bone Hammer using RSM Technique

Rapid prototyping (RP) uses a cycle where a real model is made by explicitly adding material as thin cross-sectional layers. Fused deposition modelling (FDM) 3D printer is being use for synthesis of ABS based bone hammer. Response surface methodology (RSM) based L27 design of experiment were adopted to perform the experiment using four influencing parameters such as layer thickness, infill percentage, orientation and nozzle temperature for the three responses deflection, hardness and weight. Response surface methodology was used for modelling and optimization of considered process parameters. In present investigation, it is evident that bone hammer fabrication process parameters have been optimized on data such as bone hammer weight 19.8091g, hardness 104.5921 BHN, and force of 15 degree deflection 36.0681 N has been produced with RSM prediction with influence of process parameters such as layer thickness 0.250 mm, infill percentage 63.3333, orientation 60 degree, nozzle temperature 240°C.

Force Control of a 3D Printed Soft Gripper with Built-In Pneumatic Touch Sensing Chambers.

This work reports on a soft gripper with three-dimensional (3D) printed soft monolithic fingers that seamlessly incorporate pneumatic touch sensing chambers (pTSCs) for real-time pressure/force control to grasp objects with varying stiffness (i.e., soft, compliant, and rigid objects). The fingers of the soft gripper were 3D printed simultaneously along with the pTSC, without requiring support materials, using an inexpensive fused deposition modeling 3D printer. The pTSCs embedded in the fingers have numerous advantages, including fast response, repeatability, reliability, negligible hysteresis, stability over time, durability, and very low power consumption. Finite element modeling is used to predict the behavior of the pTSCs under different body contacts and to design their topology. Real-time pressure/force control was performed experimentally based on the feedback data provided by the pTSCs to grasp various objects with different weights, shapes, sizes, textures, and stiffnesses using an experimentally tuned proportional-integral-derivative (PID) controller with the same gains for all the objects grasped. In other words, the gripper can self-adapt to different environments with different stiffnesses and provide stable contact and grasping. These results are validated theoretically by modeling the soft gripper in contact with the objects with varying stiffness to show that the stability of the contact motion is not affected by the stiffness of the environment (i.e., the grasped object) when constant PID control gains are used.

Stable magic angle spinning with Low-Cost 3D-Printed parts

A 3D-printed double-bearing magic angle spinning (MAS) system was developed with a home-built 4.0 mm MAS nuclear magnetic resonance (NMR) probe at 7 T. Various fused deposition modelling 3D printers were used to produce spinning modules of ignorable materials costs for rotors with a diameter of 7.0, 4.0, and 3.5 mm. High-performance MAS experiments on the 4.0 mm-diameter model using a pencil-type ceramic rotor and 3D-printed drive cap resulted in a high-resolution 1H NMR signal of silicone grease. The 3.5 mm-diameter MAS system reached a spinning frequency of 23 kHz. Furthermore, 3D-printed inserts were designed for various rotor sizes which can isolate the sample from humidity for a duration of more than a week. Single crystal inserts for MAS rotors of commercial probes can readily be printed using two-color printers. Those developments enable customized low-cost MAS NMR for both adapting existing and manufacturing new probes, respectively.

Impact of Drug Loading Method on Drug Release from 3D-Printed Tablets Made from Filaments Fabricated by Hot-Melt Extrusion and Impregnation Processes.

The purpose of this study was to investigate the impact of the drug loading method on drug release from 3D-printed tablets. Filaments comprising a poorly water-soluble model drug, indomethacin (IND), and a polymer, polyvinyl alcohol (PVA), were prepared by hot-melt extrusion (HME) and compared with IND-loaded filaments prepared with an impregnation (IMP) process. The 3D-printed tablets were fabricated using a fused deposition modeling 3D printer. The filaments and 3D printed tablets were evaluated for their physicochemical properties, swelling and matrix erosion behaviors, drug content, and drug release. Physicochemical investigations revealed no drug–excipient interaction or degradation. IND-loaded PVA filaments produced by IMP had a low drug content and a rapid drug release. Filaments produced by HME with a lower drug content released the drug faster than those with a higher drug content. The drug content and drug release of 3D-printed tablets containing IND were similar to those of the filament results. Particularly, drug release was faster in 3D-printed tablets produced with filaments with lower drug content (both by IMP and HME). The drug release of 3D-printed tablets produced from HME filaments with higher drug content was extended to 24 h due to a swelling-erosion process. This study confirmed that the drug loading method has a substantial influence on drug content, which in turn has a significant effect on drug release. The results suggest that increasing the drug content in filaments might delay drug release from 3D-printed tablets, which may be used for developing dosage forms suited for personalized medicine.