Method Makes 3D Printing More Economical and Ecofriendly
#Eco3D
Method Makes 3D Printing More Economical and Ecofriendly
#Eco3D
Research Terms
This solvent-assisted 3D-printing process directly prints polymer structures at room temperature, enabling a customization not achievable with traditional manufacturing. Available polymer 3D-printing systems require elevated temperatures to plasticize the build material before dispensing, which leads to undesirable thermal residual stress in the finished product and high energy consumption. The market for plastic 3D printing was valued at $494 million in 2017 and should reach nearly $2 billion by 2023.
Researchers at the University of Florida have developed 3D-printing of polymer structures that reduces waste, allows for the construction of complex structures at low cost, and enables the making of multi-material parts using an in-situ mixing-then-printing approach while printing is done at room temperature.
3D printing of a variety of polymers, mainly thermoplastics at room temperature
This 3D-printing process uses polymers dissolved in a chemical solvent as the ink. The ink is printed in air at room temperature in an enclosed chamber. At the same time, a non-solvent is delivered as a nebulized mist to the part being printed in order to partially solidify it. The printed part can be further immersed into a coagulation bath to complete the solidification process. The consumed solvent and non-solvent are reclaimed for recycling and reuse.
This nanoclay colloid combines with hydrogel ink as a self-supporting internal scaffolding material, providing 3D-printed hydrogel precursor structures with the mechanical strength to maintain integrity without the need for rapid solidification or a support bath. To date, the structural integrity of 3D-printed hydrogel structure models depends on two prevailing methodologies during printing: support-bath-enabled fabrication and rapid solidification. In support-bath-enabled fabrication, 3D structures print within a bath containing various supportive materials or substances, called a support bath. This is feasible for some materials and structures, but removing the bath material afterwards is not always possible. In rapid solidification, effective stimuli quickly cause the structures to solidify as they print. However, this constrains material selection and achievable geometries. As an alternative to these two modes of maintaining structural integrity during printing, researchers at the University of Florida have developed a nanoclay colloid that integrates into the hydrogel ink; the mechanical strength of the colloid allows the structure to maintain its shape in air during deposition. Once the entire structure is printed, researchers gel or crosslink the hydrogel precursor component of the ink to stabilize the final hydrogel structure.
3D printing of self-supported hydrogels free from the constraints of rapid solidification, gelation, curing, or support baths
Laponite nanoclay is made up of nanoscale platelets/discs. When dispersed in water, these platelets adopt a stable “house-of-cards” arrangement as the aqueous Laponite suspension equilibrates, resulting in a transparent colloidal suspension. Because of this arrangement, the colloid behaves as a solid up to a certain physical stress level. Above that level, the arrangement breaks down and the colloid behaves as a liquid. This allows its extrusion as a liquid from the 3D printer, and then its return to a stable arrangement to retain the printed shape. The hydrogel ink formulations containing the nanoclay colloid retain these flow properties and so maintain their structural integrity during printing. A stimuli applied to crosslink or gel the hydrogel component of the ink stabilizes the structures for handling.
This binder-based 3D printing process allows the production of metallic, ceramic, and composite structures at room temperature and normal atmospheric conditions. 3D printing, also known as additive manufacturing, creates structures by successively adding material layers on top of each other. 3D printing of metal and other advanced material parts is increasingly common in the medical, automotive, aerospace, and defense industries. The global 3D printing metal market is expected to exceed $796 million by 2026. The widely adopted metal 3D printing technologies require high temperature, high energy output steps in highly controlled environments, which can make printing metal parts inefficient and inconvenient. Researchers at the University of Florida have developed a metal 3D printing system that prints metallic as well as ceramic and composite parts at room temperature and ambient environmental conditions.
3D printing that creates metallic, ceramic, and composite parts at room temperature, useful for on-demand replacement parts, functional prototypes, electronics, and much more
This 3D printing process uses a liquid polymer binding material mixed with the metallic and/or ceramic powders to form a suspension that functions as an ink, later extruded using the proper printing equipment. This setup is used to print the metallic, ceramic, or composite part in-air under an induced binder phase-separation environmental conditions and/or ambient conditions. Subsequent thermal sintering of the print burns away the binding material and fuses the metallic or other particles to form the final part. The densification degree of the final part is tunable, serving as a manufacturing platform for widely different application-related needs, making both porous and dense structures manufacturing feasible. As needed, users can mix various metal and/or ceramic powders at different ratios to design parts with a functional gradient based on desired alloys.
This 3D printer uses intersecting inkjets that print then mix reactive materials to create functional biological structures successfully. Bioprinting, or using 3D printing to assemble biological structures, benefits healthcare fields, such as tissue engineering and regenerative medicine. Unfortunately, ingredient materials for making bio-inks sometimes react to each other, resulting in inks that are difficult to print or even unprintable because they’ve undergone gelation or increased in viscosity, for example.
Researchers at the University of Florida have developed a 3D printer that forms biological structures from reactive materials by using intersecting jets to simultaneously deposit the materials as they mix. Printed droplets mix and coalesce with one another, creating 3D structures with a droplet size-based voxel resolution. This procedure enables the precise fabrication of biological structures from materials previously incompatible with conventional 3D printing.
3D printer with intersecting jets to print biological structures from reactive materials and structures having a compositional gradient
This 3D printer creates biological structures out of reactive materials by simultaneously depositing the droplets of each reactive component onto a substrate using independent inkjets. Once the droplets contact the substrate, they collide, mix, coalesce, and solidify at a single location. The numerous layers of droplets collectively form the biological structure. This procedure improves efficiency and control for reactive material printing. It has printed neural stem cell (NSC) spheres, acellular and cellular alginate structures, and gradient hydroxyapatite (HAP) structures, and it can address various advanced biological fabrication applications, such as the production of structures having a compositional gradient.
This 3D printing support bath holds extruded material in a hydrophobic suspension that has strong thermal stability, enabling freeform fabrication of complex hydrophobic structures from inks with varying cross-linking or solidification requirements. The global market for 3D printing should exceed $23 billion by 2025. Freeform 3D printing of functional structures via extrusion is popular due to its easy implementation, high efficiency, and compatibility with a wide range of printable materials. However, in order for the printed object to retain its shape, conventional 3D extrusion printing techniques require either support scaffolds or rapidly solidifying or self-supporting materials, which can limit the selection of printable materials and probably weaken the physical or mechanical properties of the final object. Other techniques retain the printed shape by using support baths. These baths are typically hydrophilic, however, which can distort extrusion of fine features when printing complex hydrophobic structures. Available hydrophobic support baths are sensitive to temperature changes and lose supporting function at increased operating temperatures, limiting potential printing applications of certain polymers and other materials that cross-link or solidify at higher temperatures.
Researchers at the University of Florida have developed a hydrophobic support bath for 3D printing freeform structures from hydrophobic printing materials. The bath preserves proper extrusion of finer features when printing from hydrophobic inks and exhibits thermal stability to maintain supporting functions at higher cross-linking or solidification temperatures.
3D printing of complex hydrophobic functional components that advance fields such as soft robotics, wearable sensing, bioprocessing, and microfluidics
The yield-stress support bath material consists of fumed silica nanoparticles dispersed in a volume of mineral oil. A hydrophobic ink deposits into the fumed silica suspension via a 3D printing extrusion nozzle and retains its structural shape during printing. The bath holds it in place until the whole structure is complete. This intermediate structure may remain liquid or only partially solidify after printing. It then receives heat, ultraviolet radiation or other cross-linking mechanisms to initiate cross-linking until it completely solidifies to form the finished article. This hydrophobic support bath facilitates printing of complex 3D structures from various hydrophobic inks such as polydimethylsiloxane (PDMS), SU-8 resin, and epoxy-based conductive inks. The bath also has strong thermal stability and UV transparency to support different cross-linking mechanisms for curing various hydrophobic ink materials.
This nanoclay support bath stabilizes 3D-printed liquid build material (including hydrogel) structures during fabrication, eliminating the need for the structure to undergo a rapid phase change (usually solidification, but sometimes curing or gelation). The traditional approach for liquid build material 3D printing to maintain structural integrity is solidification-while-printing, wherein each layer completely solidifies prior to the deposition of a subsequent layer. This approach poses several problems, such as clogging of the extrusion nozzle depositing the hydrogel, difficulty in printing support structures as they undergo phase change, and weaker interfacial strength between two sequential layers of a structure. To resolve these issues, researchers at the University of Florida have developed a support bath that uses a nanoclay colloid. The stable nanostructure of the colloid behaves like liquid when accepting the deposition of the structure by the extrusion nozzle, and then behaves like a gel to support the structure until it solidifies, enabling truly freeform fabrication of intricate structures. The colloid, unlike other support materials, is insensitive to most stimuli that solidify, or cure, liquid build material structures and is easy to remove in order to harvest the printed object after phase change.
3D printing of various liquid build materials, including hydrogels, free from the constraints and problems of rapid solidification, gelation, or curing
Laponite nanoclay is made up of nanoscale platelets/discs. When dispersed in water, these platelets adopt a stable "house-of-cards" arrangement as an aqueous Laponite suspension equilibrates, resulting in a transparent colloidal suspension. Because of this arrangement, the colloid behaves as a solid up to a certain physical stress level. Above that level, the arrangement breaks down and the colloid behaves as a liquid. In the support bath, the extrusion nozzle exerts enough pressure on the nearby sections of the nanoclay to make it behave like a liquid and accept the deposition of liquid build materials via the nozzle. Once the nozzle has moved on, the nanoclay returns to its gel-like solid state, supporting the deposited structure.
This encapsulation nozzle uses a coaxial configuration with three channels to fabricate materials into capsules with two layers of protective coatings. Encapsulation is a manufacturing procedure that aims to atomize, immobilize, protect, and control the release of materials by housing them within capsules. Researchers have used this procedure to create capsules of materials such as living cells, pharmaceutical compounds, chemicals, and flavors. Many agricultural, pharmaceutical, and chemical industries are interested in encapsulation mechanisms that can create material capsules with multiple layers to facilitate multiple distinct functions, rather than capsules with just a single layer. However, available multi-layered encapsulation procedures are not effective and are difficult to produce.
Researchers at the University of Florida have developed a proficient multi-layered capsule fabrication system by creating a nozzle device that utilizes a coaxial dispensing mechanism. The nozzle has multiple concentric channels around a common axis that simultaneously dispense the core material along with the different surrounding materials, enabling multi-layered capsule fabrication. The multiple layers of the capsules support additions to the material, such as reinforced surfaces to provide greater protection and stability.
Encapsulation nozzle with three concentric dispensing channels that fabricates capsules with more than one shell layer
This coaxial nozzle produces multi-layered capsules. The nozzle is made up of three channels (core flow, annular flow, and sheath flow) that have a common axis and together form the core, inner shell, and outer shell of the capsule, respectively. The different liquid materials exit through the channels of the coaxial nozzle to form a compound liquid flow that creates the multi-shelled, multi-layered capsules. The capsule formation process varies based on the velocity or flow rate of each liquid material and its particular properties. Syringe pumps deliver the liquid materials into the different channels, and an ultrasonic vibrator helps break up the flow of the fluid in the nozzle, allowing the multi-layered capsules to form more effectively.
This biocompatible matrix bath enables rapid 3D printing of thick tissue analogues with custom features. Tissue engineering is a rapidly growing field that requires advanced fabrication techniques to create permeable thick constructs with specific channels, cavities, and cell compositions similar to tissue. Common thick tissue fabrication procedures are labor-intensive, inefficient, and preclude on-demand feature design, restricting potential for widespread use. Embedded printing processes utilizing cross-linkable matrix materials hold the most promise for rapidly creating constructs with smooth, intricate channel networks. However, tissue matrix materials suitable to these processes are rare, and those available are generally unfit for cell culture applications or lack long-term stability.
Researchers at the University of Florida have developed a flexible, embedded bioprinting process for producing custom biological tissue structures. The polymer-based composite hydrogel matrix bath supports high cell density and retains complex features to enable fabrication of living thick tissue analogues on demand.
Bioprinting matrix bath that forms custom permeable thick tissues for use in disease research, drug development, and in vivo regeneration
The matrix bath material is a composite of microgels, a gelatin-based hydrogel precursor, and harvested cells specific to the tissue application. To create features in the matrix bath, an extrusion tip deposits sacrificial material into the composite, forming an intricate filament network. The composite material adjacent to the moving tip liquefies as microgels slide and deform around it, allowing the sacrificial ink to flow out of the extrusion tip smoothly. The microgels then re-solidify upon tip removal, trapping the sacrificial material. After cross-linking the hydrogel matrix, removing the sacrificial material leaves embedded open channels and chambers throughout the composite hydrogel construct. This results in permeable thick tissue analogues once cells inside the matrix reach maturity.
This freeform additive manufacturing process prints parts from a variety of engineering polymers using a deposition solution that coagulates at room temperature. 3D printing is an excellent tool for rapid prototyping or creating complex parts for specialty applications including toys, prosthetics, and robotics. The 3D printing market in the United States is expected to reach $16.8 million by 2025. Common 3D printers work by melting the polymeric build material and depositing it in layers to create a part, which often requires printing external structures to support spanning features in the part design. The act of heating the build material before deposition creates undesirable thermal residual stresses in printed parts and limits the range of polymers suitable for printing. Additionally, available 3D printing processes have inconsistent production quality, which prevents them from fabricating geometrically precise parts.
Researchers at the University of Florida have developed a versatile additive manufacturing process that fabricates precision plastic structures from a wide variety of polymers at room temperature without requiring printed support structures. This process does not require elevated temperatures, eliminating potential residual stresses in printed prototypes and end-use parts.
Additive manufacturing process that expands the range of printable polymers and improves geometric precision
This additive manufacturing process uses a support bath along with build materials that solidify at room temperature to create 3D printed parts with superior properties. The process begins by dissolving a polymeric build material in a solvent to produce an extrudable build material. This material can be a thermoplastic or non-thermoplastic engineering polymer which dissolves at room temperature or at an elevated temperature upon stirring or agitation of the mixture. The printer then deposits this solution into a yield stress support bath, forming the entire 3D part. The completed part remains in the support bath as either a liquid or a partially coagulated solid. Immersing the support bath container with the finished part inside in a coagulation solution fully solidifies the printed material to form a functional part which can be removed from the support bath.
