Researchers from The NYU Tandon School of Engineering and the Max Planck Institute for Intelligent Systems (MPI-IS) in Tübingen and Stuttgart, Germany, have designed and 3D printed an open-sourced quadruped robot dog called the ‘Solo 8.’ When compared to the price tag on Boston Dynamics the automated pooch relatively low cost and is easy and […]
University of Minnesota researchers use motion capture technology to 3D print sensors directly onto expanding organs
Researchers from the University of Minnesota have devised a novel method of deploying Hollywood-esque motion capture technology to assist the 3D printing of sensors onto organs that expand and contract. Printing directly onto moving soft tissues is challenging because sensors need to be able to adapt to the organ’s constantly changing parameters. The research team’s […]
MesoScribe 3D printed electronics earns $4.7M development grant from DOE
CVD MesoScribe Technologies Corporation, a subsidiary of New York’s CVD Equipment Corporation, along with 4 other collaborators has been awarded $4.7 million to develop its electronics 3D printing technology as part of a project led by Pennsylvania State University. Funding was provided by the U.S. Department of Energy’s (DOE) Advanced Research Projects Agency-Energy (ARPA-E), and the particular field […]
Wireless monitoring of blood flow enabled by Georgia Tech’s implantable aerosol jet printed biosensor
Researchers from the Georgia Institute of Technology and Hanyang University, Korea, have developed the first aerosol jet printed (AJP) biosensor for wireless monitoring of blood flow. In a study published in Advanced Science, the team have used a novel AJP technique to 3D print an implantable and stretchable electronic system. This maintains a circuit-free and low-profile […]
University of Pittsburgh awarded over $1 million to develop quality assurance for 3D printed turbine components
Researchers from the Swanson School of Engineering have received over $1 million in combined funding from the U.S. Department of Energy (DoE) and the University of Pittsburgh. The funding is intended to support the development of an effective quality assurance method for the additive manufacturing of new-generation gas turbine components. Lasting three years, Xiayun (Sharon) Zhao, […]
UV Assisted Direct Ink Writing of 3D Printed and “4D Printed” Shape Memory Epoxy Parts
The magic of 3D printing has touched most of us in some way by now, as schools in many countries are establishing programs, libraries offer makerspaces for patrons, and designers like architects show us their often bold new 3D printed works made possible by accessible new technology. Some researchers, designers, and engineers not only envision the next step, however, but have already made strides in 4D innovation—characterized by parts that are not only highly functional but may be smart enough to morph into different shapes or textured on an as-needed basis.
Researchers from both Southwest Jiaotong University and Georgia Institute of Technology discuss their findings on exploring both 3D and 4D printing via UV-assisted direct-ink write printing. While noting that traditional 3D printing processes make use of typical materials like ABS, PLA, and more, the researchers looked toward epoxy for more expansive uses which may require coating and adhesives. Epoxy is also known for being mechanically strong, and more resistant in the face of temperature and chemicals—qualities that make it suitable for applications like aerospace.
Previously epoxy has presented challenges with strain break and affordability, but 3D printing with direct ink writing capability has been more successful with the use of nanoparticles that add a ‘shear-thinning effect.’ The thermal curing process can be an issue though if not performed at lower temperatures, and with close control and monitoring.
High temperatures may lead to warping of the printed object, though, and this alternative preparation of ingredients for the direct-writing ink has been considered ‘tedious,’ according to previous researchers. Others have developed DIW processes with UV curing. It was successful in applications for creating items such as conductive spring coils and freestanding nanocomposite strain sensors, but there were still significant challenges such as clogging, brittleness, and printed parameter issues.
The research team created a new method, still relying on UV-assistance for curing, but in two stages:
“A new resin containing rapid photocurable resin and thermally curable epoxy oligomer is reinforced with fumed SiO2, which can be utilized as ink for DIW printing,” state the researchers. “Each layer is printed followed by ex situ UV curing, which can efficiently avoid nozzle clogging. The flexible network formed by the UV curable resin can hold the shape of the part very well even at an elevated temperature.”
“After DIW printing, the part with the complex structure is moved into a heating oven and thermally cured similar to conventional epoxy resin. Moreover, good interfacial bonding can be achieved by forming chemical bonds between different filaments leading to isotropic mechanical properties. This two-stage curing process enables the fabrication of interpenetrating polymer network (IPN) epoxy composites, which show high toughness with tunable mechanical properties. The printed epoxy composite also shows a good shape memory effect with a high shape fixity ratio, shape recovery ratio, and cycling stability.”
Schematic illustration of the 3D printing epoxy composite material
With the new DIW method, they printed:
- Recyclable vitrimer epoxy
- PDMS (polydimethylsiloxane)
- Hydrogels
- Conductive silver lines
The researchers state that lower speed is an issue with this technique, but other benefits make up for that, such as ‘excellent interfacial bonding’ of materials and ‘widely tunable mechanical properties’ that are apparent in the post-curing stage. In 3D printing with epoxy composites, one layer of material was deposited with DIW, and then it was UV cured for ten seconds. This is repeated for each layer, allowing for printing of parts with complex geometries, later cured for two hours and post-cured for one hour.
“After that, the epoxy oligomer in the first network was polymerized to form an IPN with highly enhanced mechanical properties,” state the researchers.
Photographs and SEM images of the 3D printing with photo and thermal cure results of epoxy composites. The photos above the dashed line show the printed structures with the photo cure, and the photos under the dashed lines show the structures with two-stage cures (photo cure and subsequent thermal cure). (a) Square-shaped lattice structure; (b) gear wheel; (c) spiral swirl bowl; (d) 3-links trophy; (scale bars in a–d are 6 mm); (e) lattice structure with a single-layered wall and its enlarged SEM images.
The nanocomposite ink, measured with a viscometer, began to exhibit shear-thinning behavior as silica was added, allowing for successful extrusion. In testing, the team created numerous complex structures with a 22 GA nozzle (0.41 mm inner diameter). Not only was 3D printing with their ink sufficient, but they deemed the results to be excellent. Along with this, they began 3D printing with a focus on shape memory, testing their efforts on a 3D printed logo that responded within ten seconds after being immersed in a hot oil bath. Results were the same with a printed test strip also.
With a wide choice of UV-curable resin, thermal curing resin and nanoparticles, this UV-assisted DIW 3D printing via a two-stage curing method can broaden the implementation of 3D printing to directly fabricate thermosetting materials with tunable and enhanced properties for high performance and functional applications,” concluded the researchers. If commercialized this kind of a process would have a broad range of applications in light-based applications.
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[Source / Images: ‘Fabrication of Tough Epoxy with Shape Memory Effects by UV-assisted Direct-ink Write Printing’]
UL and Georgia Tech Continue Research Into Impact of 3D Printing Emissions on Indoor Air Quality
In 2015, non-profit safety science company Underwriters Laboratories (UL) and its Chemical Research Initiative, the Georgia Institute of Technology (Georgia Tech), and Emory University Rollins School of Public Health, worked together to conduct a two-year study on desktop 3D printer emissions. Over the course of the study, Dr. Marilyn Black, the Vice President and Senior Technical Advisor at UL Chemical Safety, and the rest of the research team found that desktop 3D printer emissions can actually pose a potential health threat.
This month, UL Chemical Safety, a science-directed research group that is part of UL, and Georgia Tech released their previous findings, and announced a new body of research that will look into the impact of 3D printing on indoor air quality.
Dr. Marilyn Black
Dr. Black stated, “Following our series of studies – the most extensive to date on 3D printer emissions – we are recommending additional investments in scientific research and product advancement to minimize emissions, and increased user awareness so safety measures can be taken.”
The previous study determined that while many desktop 3D printers are in operation, they generate ul
Additionally, the team’s research showed that over 200 different volatile organic compounds (VOCs), many of which are either suspected or known carcinogens and irritants, are also released into the air while 3D printers are operating.
UL has now begun a dedicated campaign to raise awareness of the potential air quality risks of 3D printing, and to educate users on how to minimize their exposure to VOCs and UFPs. Dr. Black is advocating for a complete risk assessment, which could factor in considerations in personal sensitivity and dosage, in order to more “fully understand the impact of the chemical and particle emissions on health.”
[Image: UL Chemical Safety]
“Studies have shown that fused filament fabrication (FFF) 3D printers designed for general public use emit high levels of ultrafine and fine particles. Preliminary tests with in vivo, in vitro and acellular methods for particles generated by a limited number of filaments showed adverse responses,” explained Dr. Rodney Weber, Georgia Tech’s primary investigator of the research.
There are plenty of different factors, from filament type and color to nozzle temperature and even the brand of 3D printer, that can affect the level of emissions, and while there are definitely products out there that purport to make 3D printing safer, there isn’t a lot of available marketplace information just yet.
These findings from Georgia Tech and UL come as 3D printing continues to gain momentum in commercial, consumer, educational, medical, and military applications, and if the issue of harmful emission levels is not addressed, there could be a potential public health risk.
3D printers are being used more and more often in school settings, and as children are the most sensitive population to the impact of contaminants such as VOCs, we need to make sure we’re protecting them by reducing their exposure to emissions.
We can lower the potential risks by following some simple rules:
- Operating 3D printers in well-ventilated areas
- Standing away from operating 3D printers
- Setting the nozzle temperature at the lower end of the suggested range
- Using 3D printers and filaments that have been tested and verified to have low emissions
Researchers from UL and Georgia Tech recently published two scientific research papers, titled “Investigating particle emissions and aerosol dynamics from a consumer fused deposition modeling 3D printer with a lognormal moment aerosol model” and “Characterization of particle emissions from consumer fused deposition modeling 3D printers,” in the journal Aerosol Science and Technology. Additionally, two more papers regarding the “plethora of chemical emissions” and 3D printer particle toxicity are currently under review.
Particle number (a), surface area (b) and mass (c) emissions for ABS filament d green color on printer A for 3 objects taking about 1 h, 4 h, and 7 h to print. Each bar indicates the emission (TP) from one print object; colors indicate different particle size ranges. Values on the colored bars are the ratios of emissions from such particle size range over total emissions. [Image: Georgia Tech & UL]
Based on the current research, and further collaboration with third-party stakeholders, a new UL/American National Standards Institute (ANSI) consensus standard has been developed for testing and evaluating 3D printer emissions. UL/ANSI 2904 is currently available for review and comment, and the final standard should be ready next month.
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Georgia Tech and Beida 3D print engineering strength origami
A 3D printing research collaboration between Georgia Institute of Technology and China’s Peking University (Beida) has yielded transformable structures that can support up to 100 times their own weight. A continuation of previous studies demonstrating self-assembling tensegrity structures, the results of this research is a step forward for engineering applications of origami structures. Origami engineering principles As pointed […]
Researchers Make Strong, 3D Printed Expandable Origami Structures for Engineering Applications
Rearranging the same units can change a structure from one that can support a load 100 times its weight to one that will fold flat under the same load. [Image: Soft Matter]
A collaborative team of researchers from the Georgia Institute of Technology, the Beijing Institute of Technology, and Peking University are using 3D printing to directly build reconfigurable origami assemblages that can expand and fold. But even better, the 3D printed structures also have enough load-bearing capability and strength to be used in engineering applications.
In a paper published in Soft Matters, titled “3D printing of complex origami assemblages for reconfigurable structures,” the researchers explained how they used digital light processing (DLP) 3D printing to fabricate structures with hollow features.
With this method, far less support material is required for 3D printing hollow features, and softer materials, necessary for flexible structures, can be used.
The abstract of the paper reads, “Origami engineering principles have recently been applied to a wide range of applications, including soft robots, stretchable electronics, and mechanical metamaterials. In order to achieve the 3D nature of engineered structures (e.g. load-bearing capacity) and capture the desired kinematics (e.g., foldability), many origami-inspired engineering designs are assembled from smaller parts and often require binding agents or additional elements for connection. Attempts at direct fabrication of 3D origami structures have been limited by available fabrication technologies and materials. Here, we propose a new method to directly 3D print origami assemblages (that mimic the behavior of their paper counterparts) with acceptable strength and load-bearing capacity for engineering applications. Our approach introduces hinge-panel elements, where the hinge regions are designed with finite thickness and length. The geometrical design of these hinge-panels, informed by both experimental and theoretical analysis, provides the desired mechanical behavior. In order to ensure foldability and repeatability, a novel photocurable elastomer system is developed and the designs are fabricated using digital light processing-based 3D printing technology. Various origami assemblages are produced to demonstrate the design flexibility and fabrication efficiency offered by our 3D printing method for origami structures with enhanced load bearing capacity and selective deformation modes.”
Many 3D printed structures with unique properties have been inspired by origami, opening up applications in soft robotics and self-folding structures. While most origami structures mean thin sheets being joined together with binding elements like glue, the research team found a way to make several 3D assemblies in one step, without needing to connect smaller parts together. The team, led by Zeang Zhao, developed a new polymer and used geometrical design to move towards using origami for engineering structures.
To build the origami, the team developed a novel new elastomer, which makes it possible for the structure to be created from a single component. The elastic polymer material can be 3D printed at room temperature and set with UV light, which forms a soft, foldable material that can be stretched up to 100%. This material was used for the whole 3D assembly. DLP 3D printing was used to build structures, made up of various combinations of individual units of origami, without requiring any extra assembly steps.
By altering how each origami unit is connected, the structures can be designed to have different load-bearing capabilities: vitally important for applications in engineering. One of the test structures was even able to support a load that weighed 100 times more than the structure itself did. But here’s the really interesting part – just by rearranging the same individual units in a different way, the team was able to build a bridge that, under the same heavy load, would fold flat.
The structures were designed with thick panels, which were separated by hinges not unlike the creases in a piece of paper. The hinges made it possible for the angle between the panels to vary between 0° and 90°. Hinge thickness is important for a structure’s mechanical properties: if it’s too thick, it won’t fold well, while if it’s too thin, it might not be able to support the structure’s weight. In addition, the researchers made sure that the high strain and stress the structures experienced during folding was localized specifically to the hinges, so the panels would not end up deformed.
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[Source: Physics World]