More than one crime, including multiple murders, has been solved with help from 3D printing, as the technology can help recreate forensic evidence. But in a new study entitled “A Preliminary Investigation into the Accuracy of 3D Modeling and 3D Printing in Forensic Anthropology Evidence Reconstruction,” a team of researchers examines just how impactful 3D printing and 3D modeling actually are in solving cases.

The researchers affirm that 3D printed evidence has been useful in several court scenarios. 3D printed replicas of bones can be more effective than photographs at showing the nature of injuries to victims, but while there is quite a bit of circumstantial evidence demonstrating that this is the case, there is still a lack of published empirical evidence. This study aims to change that.

“Digital methods have become increasingly popular and have been used in place of traditional photographs for demonstrating evidence in court for a number of years,” the researchers point out. “It can be argued that both photographs and 3D virtual models may not always provide accurate representations of their original subject. First, subjects can be distorted via the light or angle used in a photograph or a virtual rendering; second, when presenting a 3D object such as a bone as a 2D image, whether as a photograph or a virtual model, depth and spatial information is immediately lost; and third, virtual 3D models are stereoscopic, meaning that they only give the illusion of depth. A novel way to address these problems has been the introduction of 3D printed replicas: a physical 3D object that has depth, haptic, and spatial characteristics.”

For the study, the researchers borrowed archaeological human bone specimens from University College London: a cranium, a clavicle and a first metatarsal. The bones were scanned and then 3D printed using six different commercial 3D printers: an Ultimaker 2, an RS Pro, an EOS P1, an Objet500 Connex 3, a Form 2 and a Makerbot 2. Osteometric measurements were taken of the bones and the 3D printed replicas by five doctoral students in archaeology and forensic anthropology.

“The results from this study found good intraobserver reliability and indicate good accuracy,” the researchers state. “The data resulted in mean differences ranging from −0.4 to 1.2 mm (−0.4% to 12.0%) for the virtual model data, and from −0.2 to 1.2 mm (−0.2% to 9.9%) for 3D print data.”

Overall, the virtual models and 3D printed replicas were highly accurate to the source specimens. The cranium model showed the most inaccuracy, likely because of its complexity and large curved surface. Three major conclusions were reached from the study:

• It is possible to produce accurate 3D printed replicas from CT scanned skeletal elements
• Each printer tested produced replicas with mean differences within ±1.2 mm
• SLS was the most metrically accurate printer type used, and produced prints that were the most aesthetically true to the original specimen

Recommendations include employing the highest CT scan resolution possible, using a high/hard CT reconstruction filter, applying an appropriate degree of surface smoothing, and using a 3D printer that does not require support structures. The researchers conclude that 3D printed forensic samples are indeed a valid method of providing evidence in court.

“Further work will explore 3D printer capabilities for printing forensic case specimens exhibiting trauma and fine details, and crucially an experimental investigation into the evidential impact of using 3D techniques for demonstration of evidence,” the researchers state. “The issues surrounding the validity and reliability of printed replicas and their evidential value must be addressed urgently, to avoid a lack of transparency in evaluative interpretation and the risk of misleading evidence creating unsafe rulings.”

Authors of the paper include Rachael M. Carew, Ruth M. Morgan and Carolyn Rando.

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EBF3 manufacturing system.

Electron Beam Freeform Fabrication, also known as EBF3, is a wire feed metal 3D printing technique developed by NASA for aeronautics. It has a higher deposition rate than other rapid manufacturing methods, is well-suited for manufacturing reactive alloys, like aluminum and titanium, and can print complex geometric shapes with no material waste. Wire is fed into a base plate and melted by an electron beam into a solid, which layer by layer builds up into a near-net shape part. With CAM, a predetermined trajectory is stored in a computer, and the base plate or the wire feed and electron beam gun can be manipulated in the same way.

Unfortunately, EBF3 has to be carried out inside a chamber, which limits the size of the part and takes a long time to evacuate. A team of researchers from RWTH Aachen University and Tsinghua University published a paper, titled “A new 3D printing method based on non-vacuum electron beam technology,” about their investigation into using non-vacuum electron beam welding to 3D print metal parts.

System composition of 3D printer based on NVEBW machine.

The abstract reads, “Non-vacuum electron beam (NVEB) welding is widely used in industry field as a reason for its high production volumes. So a NVEB 3D printing device based on a non-vacuum electron beam welding machine from SST is designed. A serial of experiments is carried out to get a deep understand of 3D printing processing procedure using non-vacuum electron beam system and find a suitable process window. Result shows that droplet transfer mode is one of the most important parameters which determines the quality of the deposition.”

NVEB was first used in the automotive industry, due to its high production volumes, and is now used in many fields, like equipment construction and welding laboratories.

Wire feed unit.

In order to gain a deeper understanding of NVEB, the research team carried out a series of experiments on a non-vacuum electron beam-welding machine. They installed a wire feed unit and a collimator, to make the wire straight enough to be fed correctly, to turn it into a 3D printing system, and also placed four brackets for protection between the base plate and operation platform.

“More stable clamps should be adopted in the future experiments. The waviness of the part built by EBF3 is big,” the researchers wrote. “The printing procedure will be disrupted when there is a large deformation of the baseplate. The baseplate need to be fixed very tightly to stand up to the residual stress.”

The goal was to gain a deeper understanding of the 3D printing process procedure with the NVEB system, and find a good process window for the machine.

“Several pre-experiments were carried out to get basic knowledge of the processing procedure. One of the important advantage of EBF3 is the highest deposition rates, which makes it suitable for making large-scale metal structures,” the researchers wrote. “To get a high deposition rate, the accelerating voltage was set to 150kv. The energy loss of electron beam is around 50% due to the collision with atmosphere and inner wall of the nozzle.”

Deposition on a high translation and feeding speed.

The deposition was first carried out on a high translation (500mm/min) and feeding speed (1m/min), which did not completely melt the wire at some points due to a lack of heat input. The translation speed was then lowered to 400mm/min, while the feeding speed was set to 0.8m/min, which resulted in the wire melting completely. The team determined that when the feeding speed was too high, the wire would not completely melt.

Other experiments the team carried out focused on the influence of the droplet transfer mode, and the deposition gap between layers; the quality of deposition varied with distance.

“There is also no obvious difference when deposited single layer within different deposition gap between layers,” the researchers wrote.

Deposition with different feeding speed.

The researchers determined that a good wire feeding speed is around 0.85~0.9m/min, as big droplets tend to form when there is too much wire fed into the molten pool, and that the translation speed should be set under 400mm/min for a constant molten pool.

A distance of 0.2~1.7mm between the base plate and where the metal melts is better for stable deposition, and whether the material is “deposited single layer within different deposition gap between lines or layers,” there is not an obvious difference.

“To get more understand on the moving strategy, further experiment focused on influence of different gap between both lines and layers should be done in the future,” the researchers concluded. “A powerful baseplate cooling device need to be designed to get a higher deposition rate instead of waiting several minutes between each lines and layers. The wire feed unit need to be synchronized with the electron beam generator. Then more complicated figures can be test to find the potential of this NVEB 3D printing device.”

Co-authors of the paper are Shuhe Chang, Stefan Gach, Aleksej Senger, Haoyu Zhang, and Dong Du.

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Additive manufacturing has, in many studies, been compared with traditional manufacturing techniques like, for example, injection molding. In a study entitled “The Use of Selective Laser Melting to Increase the Performance of AlSi9Cu3Fe Alloy,” a group of researchers compared parts made with 3D printing to parts made with die casting, using the same material.

Aluminum and its alloys have an excellent strength to weight ratio, and AlSi9CuFe is frequently used in the automotive industry because of its mechanical strength. It is easy to machine and is usually processed by high pressure die casting, but the method has its imperfections.

“High-pressure die casting (HPDC) enables high production volumes of parts showing high surface quality,” the researchers state. “Compared to gravity casting, even more complex shapes are possible to be produced, but still, the current demands for porous structures or very small dimensions are hardly attainable. Additionally, the HPDC process is limited by the formation of defects, such as oxide films, shrinkage cavities, air porosity, etc., which cannot be eliminated. Such defects then weaken the castings structurally and exclude them for use in the field of safety applications.”

Therefore, the researchers conducted a study in which SLM 3D printing and high pressure die casting were used to produce parts using the same alloy. They then compared the properties of the parts. Porosity was examined in the samples, and transmission electron microscopy was used to observe nanoscale microstructural features. Uniaxial tensile tests were conducted, as were compressive tests and hardness measurement. Fracture surfaces were studied using scanning electron microscopy.

TEM bright field images obtained in the area of (a) a melt pool boundary and (b) a melt pool interior.

“Compared to as-cast microstructure consisting of α-Al dendrites and lamellar Al-Si eutectics, SLM yields in hierarchically heterogeneous microstructure,” the researchers conclude. “Grains are arranged in melt pools representing material melted and solidified by single laser tracks in the direction of the highest temperature gradient. They exhibit very fine cellular substructure in which the cells of α-Al solid solution oversaturated in Si and Cu are separated by eutectic network formed by cubic particles of pure Si, here 30–70 nm in size.”

The 3D printed parts showed a very fine microstructure, and overall, the parts produced by additive manufacturing exhibited greater strength than those produced by die casting, as well as greater plasticity. This is notable because it shows that 3D printing can overcome the strength-ductility tradeoff that is present in so many metals and alloys. The researchers conclude that 3D printing can improve the performance of the alloy compared to high pressure die casting, as well as produce more complex and lightweight structures, opening up new applications.

Comparison between (a) as-cast (HPDC) and (b) SLM microstructures.

This study is another example of how 3D printing can improve upon traditional manufacturing techniques. 3D printing is often hailed for its ability to speed up production, save money, and produce more complex and lightweight components than traditional manufacturing, but the researchers’ study shows that the very microstructure of 3D printed materials can be superior to that of the same materials fabricated in a traditional way.

Authors of the paper include Michaela Fousova, Drahomir Dvorsky, Marek Vronka, Dalibor Vojtech and Pavel Lejcek.

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While it may sound great to sit around and eat cookies all day, the fact is that cookies aren’t particularly healthy because they’re chock full of sugar. But, partially because obesity rates have been increasing over the last few decades, people have been more focused on reducing sugar in tasty foods like cookies, or replacing it with something else altogether, like artificial sweeteners such as sucrose. But another trend has also emerged: that of ‘clean label products’ with few or no additives. Desserts could appeal to both trends if a product’s sweetness is increased in a different way, while its overall sucrose is reduced.

Types of 3D food printing: A) Selective laser sintering, B) Inkjet printing, C) Binder jetting, D) Extrusion-based printing

A fairly new way to prepare sweet treats like cookies is 3D printing. The technology makes it possible to create complex, reproducible 3D structures impossible to make by hand alone, and can also help with more customized nutritional requirements.

Tim Meuleman, a student at Wageningen University & Research in the Netherlands, recently wrote a thesis paper, titled “Sugar reduction in cookies by using 3D food printing,” on using 3D printing to achieve sugar reduction in cookies.

The abstract reads, “3D food printing was used to prepare cookies containing different sugar replacers, and cookies containing different doughs which were layered. The effect of these preparation methods on cookie quality properties was investigated. By doing this it could be observed if 3D food printing could be used for achieving sugar reduction in cookies. The cookies were prepared by 3D food printing a dough, which contained sucrose or a sugar replacer. Correlations between the molecular weight of the sugar replacer used and physicochemical properties like texture, water activity, dry matter content, shape stability and bake stability were investigated. Furthermore, the influence of 3D printing on these properties, and the influence of layering different doughs on these properties was investigated. Also, a sensory analysis was performed, to determine the influence of the layering of doughs on perceived sweetness. The effect of molecular weight was tested for homogeneous cookies containing one of the following sugar (replacers); sucrose, xylitol, maltitol, oligofructose and polydextrose. The conclusion was that the inhomogeneous distribution of sucrose in a sugar reduced cookie by layering with a 3D printer does increase the perceived sweetness in comparison to a sugar reduces cookie where the sucrose is homogeneously distributed. The sugar replacement as well as the printing did have influence on the measured physicochemical properties, however these were only small differences. The layering does have influences on the bake stability and fracture stress, however also only small differences were observed.”

The goal of Meuleman’s thesis was to investigate the effect of different sugar replacements in cookie dough, along with the structuring of the cookies based on properties such as shape stability, taste, and texture.

Texture analysis setup

“3D printing was first used to print doughs containing sugar a single sugar replacer to evaluate the impact of the sugar replacement on 3D printing, on physicochemical attributes like final cookie texture, water activity, dry matter content and shape stability. Different doughs were prepared to find the right recipe suitable for 3D printing,” Meuleman wrote. “Next, it was investigated if printing of different layered structures with alternatively the sucrose containing dough and the dough with a sugar replacer improves the texture and/or taste of the cookies in comparison to cookies with homogeneously distributed sucrose and sugar replacers. The influence of the layering and composition of the layered structure on the final cookie properties were especially examined. Furthermore the effect of printing on the cookies was examined by comparing printed cookies to cookies where the dough was cut to shape in the same dimensions as the printed cookies.”

Meuleman used an adapted version of a recipe for a 3D printable dough that he wrote had been “found by unpublished internal experiments at TNO (The Hague, the Netherlands), acquired via Stefano Renzetti,” and chose the various sugar replacers because of the variations between their molecular weight; this allowed him to observe how cookie properties, like dry matter content and texture, were influenced.

Once cookie dough was prepared with a variety of sugar replacers, Meuleman created a design for 3D printing a rectangular cookie in OpenSCAD, which was then loaded into Slic3r before being fabricated on a byFlow 3D food printer.

Vertical and horizontal design for one cookie layer in Slic3r.

After the cookies were baked, they were packaged in aluminum foil to sit for a day, so the water could redistribute inside before the dry matter content and water activity were measured and the texture analysis was performed.

“The texture of the cookie was determined by a three-point bending test to investigate the influence of the recipe and the structure design on texture. The printability was assessed visually, by determining if the printed structure has the same dimensions, if it resembled the created design and if the dough caused any errors during printing. The stability was assessed by making measurements of the dimensions of the cookie before and after baking. Finally, the taste was evaluated by sensory test,” Meuleman wrote.

He concluded that 3D printing was a good way to lower the sugar content in cookies, because it does not negatively influence the texture and also increases the perceived sweetness without having to add any artificial sweeteners.

Future research could focus on developing dough that is easier to 3D print.

“Other interesting effects that could be investigated are: researching other influences from changing the sugar replacer than the changing the molecular weight of the sugar or sugar replacers, like water binding capacity,” Meuleman concluded. “These influences could also be applied to the data collected in this thesis.”

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A team of researchers led by Jan Schroers, Professor of Mechanical Engineering and Materials Science at Yale, has developed a way to 3D print objects from metallic glass. The material is stronger than metal yet has the pliability of plastic, which makes it extremely valuable. The research is published in a paper entitled “3D printing metals like thermoplastics: Fused filament fabrication of metallic glasses.“

Extrusion-based 3D printing of metals is still a challenge, but bulk metallic glasses, or BMGs, can undergo continuous softening upon heating, like thermoplastics can. The research team, which also included researchers from Desktop Metal as well as MIT, demonstrated that BMGs can be used to create solid, strong metal components under ambient conditions similar to those in thermoplastic 3D printing.

“It was even surprising to us how practical this process is once we had the processing conditions figured out,” Schroers said.

Metal 3D printing, while gradually becoming more accessible and affordable, is still quite costly, and powder-based 3D printing is prone to flaws and imperfections, which make it even more expensive. The BMG research could save a lot of money and resources for manufacturers, and also eliminate the need to choose between the benefits of thermoplastics and metals.

The researchers worked with a well-characterized and readily available BMG material made from zirconium, titanium, copper, nickel and beryllium. They used amorphous rods one millimeter in diameter and 700 millimeters in length. They used an extrusion temperature of 460°C and an extrusion force of 10 to 1000 Newtons to force the softened fibers through a 0.5 diameter nozzle. A surprise came when they characterized the 3D printed parts.

“We expected high strength in the parallel-to-the-printing orientation, but were very surprised by the strength in the perpendicular orientation,” said Jittisa Ketkaew, a co-author and graduate student in the Schroers lab.

In theory, a wider range of BMGs can also be 3D printed using the researchers’ method.

“We have shown theoretically in this work that we can use a range of other bulk metallic glasses and are working on making the process more practical and commercially usable to make 3D printing of metals as easy and practical as the 3D printing of thermoplastics,” said Schroers.

There is potential for this method to be used in numerous applications, said Punnathat Bordeenithikasem, a co-author and recent Yale graduate who is currently working as a postdoctoral fellow at the NASA Jet Propulsion Laboratory, California Institute of Technology.

“Beyond prototyping, the achievable properties of the printed parts accompanied by the versatility in part design makes this 3D printing technology suitable for fabricating high-performance components for medical, aerospace, and spacecraft applications,” said Bordeenithikasem.

Authors of the paper include Michael A. Gibson, Nicholas M. Mykulowycz, Joseph Shim, Richard Fontana, Peter Schmitt, Andrew Roberts, Jittisa Ketkaew, Ling Shao, Wen Chen, Punnathat Bordeenithikasem, Jonah S. Myerberg, Ric Fulop, Matthew D. Verminksi, Emanuel M. Sachs, Yet-Ming Chiang, Christopher A. Schuh, A. John Hart, and Jan Schroers.

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Imagine not only holding a tiny ecosystem in your hand, but then eating it, in just a bite or two. That’s the concept behind Edible Growth, a 3D printed “mini vegetable garden” created by Eindhoven-based designer Chloé Rutzerveld. Rutzerveld designed the idea back in 2014, and since then, Edible Growth has grown in popularity, having been displayed in North America, Asia and Europe. Currently, the design is being showcased in Brazil’s Museum of Tomorrow, and is also featured in Rutzerveld’s new book, which was published last week.

Chloé Rutzerveld [Image: Paul Bellaart]

Edible Growth consists of a spherical 3D printed crust with several holes in it. Inside is “edible soil” filled with yeast, seeds and spores that, within days, grow into plants and mushrooms that poke through the holes in the crust, becoming a bite-sized garden that is both adorable and nutritious.

One issue with 3D printing things like fruit and vegetables is that processing them into printable paste causes a significant loss of nutrients. By growing plants inside a 3D printed case, Rutzerveld allows them to keep their original form and all of their nutritional value, while employing 3D printing to create something new and exciting. Four years after introducing the concept for the first time, Rutzerveld reflected upon the fame of Edible Growth.

“Edible Growth was my graduation project at the TU/e  in 2014,” she told the Dutch Institute of Food and Design. “It is a critical project about the use of additive manufacturing techniques which proposes to use the technology as a means to enhance natural growth instead of using the printer merely as a form-machine to create crazy shapes of chocolate, sugar and pasta. I think it went viral because it was the right time to show a skeptical and different view on 3D food printing. Also the picture of my roommate eating the prototype and a very realistic stop motion of how it grows, made people think that Edible Growth was not a prototype / future food concept but that we could already print edible ecosystems.

“Now, 4 years after the launch of the project the TEDx presentation (Calgary 2015) has over 52.000 views and at least once every two weeks I get an email concerning a question, invitation or proposal related to Edible Growth. Crazy! When I just started my studio in 2014 I didn’t want to be known as the 3D food printing girl – I thought it was very limiting but it also created a lot of pressure to come up with something new, which was as good or even better. But after a while I embraced it, because who cares how people find you. It matters that they find me somehow and are interested in the way of thinking to start something new, together.”

Edible Growth shows not only how food can be creatively 3D printed, but how it can be eaten while still growing, and how food can be grown inside the home to lessen the demand for huge agricultural tracts of land.

Rutzerveld’s other works include a plant-based stroopwafel and an experimental meat cookbook. She may not have wanted to be known as the “3D food printing girl,” but Edible Growth has opened up plenty of doors for her to explore the way food is prepared, eaten, and considered. Her book, Food Futures, will be available worldwide beginning in early 2019.

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Some accessories prepared by ultraviolet-assisted 3D printing.

There are many advantages to ultraviolet (UV)-curable systems, like energy saving, rapid curing, environmentally friendly, and high cost performance. These systems are used often with UV-assisted 3D printing, which deposits layers of photocurable liquid polymer crosslinked by an external UV light source to make an object. Silicone materials are promising for 3D printing use due to their unique properties, like thermal resistance, good transparency, and UV resistance.

A team of researchers from Hangzhou, China recently published a paper, titled “Preparation and performance of ultraviolet curable silicone resins used for ultraviolet cured coating and ultraviolet-assisted 3D printing materials,” that detailed how they synthesized a type of UV-curable silicone resin “by an easy controlled method of sol-gel with 3-methacryloxypropyltrimethoxysilane, methyltrimethoxysilane and dimethyldiethoxylsilane.”

The abstract reads, “Types of curable methacryloxypropyl silicone resins were prepared by a cohydrolysis condensation reaction with 3-methacryloxypropyltrimethoxysilane, methyl trimethoxy silane, and dimethyl diethoxy silane. The properties of the transparent resins cured by the ultraviolet were investigated in detail. The ultraviolet cured silicone material transparency was higher than 95% in the light wavenumber range of 400 nm and 800 nm, pencil hardness from 6 B to 6 H, and thermal decomposition temperature higher than 150°C. The silicone materials prepared by ultraviolet-assisted 3D printing had a water absorption coefficient of 0.21 wt% and a line thermal expansion coefficient of 5.27 × 10⁻⁴ m/k. It showed that the silicone resins can be candidates for ultraviolet cured transparent coating and ultraviolet-assisted 3D printing.”

A sol-gel method was used to synthesize the transparent silicone resins, which had various amounts of R/Si for UV-assisted 3D printing. These pre-polymer materials were 3D printed on an SLA 3D printer, and the resulting resins were deposited on slides and UV-cured.

The researchers measured the materials’ dynamic viscosity, along with the hardness of the cured samples and their apparent curing contents. They also recorded the transmittance spectra of the silicone resin pre-polymers cured on a slide, carried out thermogravimetric (TG) analysis of the 3D printed silicone resins, and performed differential scanning calorimetry (DSC) measurements of the final products.

By decreasing the n(R)/n(Si), the researchers found that they could increase the viscosity of the pre-polymers, as well as the pencil hardness of the UV-cured products.

Figure 4: The TGA curves for the silicone resins with various of n(R)/n(Si) cured by ultraviolet with 10 wt% of 2-hydroxy-2-methyl-phenyl-propane-1-one for 30 s.

“The TGA analysis (Fig. 4) showed that all the thermal decomposition temperature for the ultraviolet cured silicone materials higher than 150°C, which means that the cured silicone resins were all with fairly good thermal stability,” the researchers wrote.

The cured material is still sticky, with low hardness, if the amount of 2-hydroxy-2-methyl-phenyl-propane-1-one is less than 10 wt% of silicone resin pre-polymers – possibly because it wasn’t totally cured “for the insufficient amount of ultraviolet initiator.”

But, if the amount of UV initiator reached 10 wt%, absorption at 2333 cm⁻¹ and 1625 cm⁻¹ for methacryloxypropyl disappeared. Excessive amounts of UV photoinitiator will make the material’s properties worse, which is why the correct amount is 10 wt% of the silicone resin pre-polymer.

The researchers also investigated the influence of UV curing time, and found that when it was less than 30 seconds, the material would not completely cure. But, the cure time did not have much of an effect on the cured material’s gelation rate and hardness.

Figure 7: The FT-IR spectra for the silicone resin before and after cured by ultraviolet with 10 wt% of 2-hydroxy-2-methyl-phenyl-propane-1-one for 30 s.

“This phenomenon can be explained by the FT-IR analysis given by Fig. 7 that the characterization peaks at 1630 cm⁻¹assigned to the unsaturated double bond of the methacryloxypropyl almost vanished after the silicone resin cured by ultraviolet for 30 s, which demonstrated that the silicone resins were cured completely,” the researchers explained.

By observing the performance of the UV-cured silicone resins, it’s obvious that they can be used as transparent coating.

“Ultraviolet curable transparent acrylic modified resins were prepared by cohydrolysis condensation reaction with 3-methacryloxypropyltrimethoxysilane, methyl trimethoxy silane and dimethyl diethoxy silane. It showed that the prepared transparent acrylic modified resins can be cured completely cured by 10 wt% 2-hydroxy-2-methyl-phenyl-propane-1-one for 30 s with transmittance up to 95% in the light wavenumber range of 400 nm and 800 nm, pencil hardness from 6 B to 6 H, thermal decomposition temperature higher than 150°C,” the researchers concluded. “It also exhibited that the silicone resin prepolymers can be used for ultraviolet-assisted 3D printing. The silicone materials prepared by ultraviolet-assisted 3D printing are with coefficient 0.21 wt% and the line thermal expansion coefficient 5.27 × 10⁻⁴ m/k. It showed that the silicone resins can be a candidate material for ultraviolet cured transparent coating and ultraviolet-assisted 3D printing.”

Co-authors of the paper are Xiongfa Yang, Qiong Chen, Haoyuan Bao, Jiangling Liu, Yufei Wu, and Guoqiao Lai.

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A mishap has resulted in the first bioprinter to be sent to the International Space Station not quite making it to its destination. Last Thursday, the Russian spacecraft Soyuz MS-10 crashed due to a malfunction during liftoff. The bioprinter, called Organ.Aut, was to arrive at the ISS and be part of the first experiments in 3D printing organ tissue in space, but it was destroyed when the spacecraft malfunctioned.

“The bioprinter was in the habitation module, which jettisoned from the escape capsule of the Soyuz MS-10 spacecraft and fully burnt,” a source told Sputnik.

Two new members of the ISS crew, Russian cosmonaut Alexey Ovchinin and NASA astronaut Nick Hague, were also aboard the spacecraft, but they safely returned to Earth in a jettisoned escape capsule. The exact cause of the incident has not yet been announced, and is being investigated by a special commission of Russia’s space agency Roscosmos. All manned launches from Baikonur Cosmodrome have been suspended until the commission can figure out the cause of the failure. Incidents like this don’t happen every day – in fact, this was the first time in modern Russian history that a manned space launch failed.

So what happens next? 3D Bioprinting Solutions, the company that created the Organ.Aut 3D bioprinter, has a backup plan, as it turns out, and is now preparing to send a duplicate bioprinter into space.

“Organ.Aut and cosmonauts have a duplicate [of the printer], it will be ready to fly to the ISS in the near future,” said Yousef Hesuani, Co-Founder and Managing Partner of 3D Bioprinting Solutions. “We will work out a separate cycle graph of the experiment for preparing the flight at the Progress spacecraft. “The current crew has already confirmed its readiness for undergoing the remote training, so we will be ready to send the scientific equipment in any case.”

The delivery of the first 3D bioprinter to the International Space Station may have hit a snag, but it’s not really more than that: a snag. Besides the second bioprinter being provided by 3D Bioprinting Solutions, there are several other bioprinters being developed for the purposes of bioprinting in outer space. It may seem odd that so many are focused on bioprinting in space, when, after all, 3D printed organs are going to be needed here on Earth, but bioprinting is actually easier in zero gravity.

Thick, viscous liquids and large nozzles must be used to bioprint on Earth, but take away gravity and it’s possible to use much thinner inks and nozzles, allowing for much more precision. While some amazing bioprinting breakthroughs have happened here on Earth, there’s a whole world of possibility that may open up once we start using the technology in space. Advanced bioprinting has already taken place in zero gravity conditions, and another bioprinter is scheduled for delivery to the ISS early next year. Still another is set to go up shortly, as well.

The Allevi Zero-G is another space-bound bioprinter. [Image: Allevi]

It’s pretty much a certainty that bioprinting in outer space will be taking place very soon, and that we can expect to see some amazing developments once the printers actually start arriving on the ISS. The real question is which of them will start achieving those developments first.

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Last spring, we heard about an intriguing research project out of Germany’s Hasso-Plattner Institute (HPI), called TrussFab. The integrated, end-to-end 3D software system made it possible to design sturdy, large-scale structures, and then determine the proper distribution of recycled plastic bottles and 3D printed connectors to fabricate a strong end product, like a bridge, that could hold human weight.

While these structures were pretty interesting, they were static, as in non-moving. But HPI has completed a new research project, called TrussFormer, that builds on TrussFab and uses hinges and linear actuators to add movement to the structures.

This new software system lets users make large-scale, kinetic structures, which involve motion and dynamic forces, out of 3D printed hubs and recycled plastic bottles. The HPI team is presenting its new paper, titled “TrussFormer: 3D Printing Large Kinetic Structures,” at the Human Computer Interaction conference (UIST) in Berlin this week; co-authors are Robert Kovacs, Alexandra Ion, Pedro Lopes, Tim Oesterreich, Johannes Filter, Philip Otto, Tobias Arndt, Nico Ring, Melvin Witte, Anton Synytsia from Oregon State University, and Patrick Baudisch.

The abstract reads, “TrussFormer builds on TrussFab, from which it inherits the ability to create static large-scale truss structures from 3D printed connectors and PET bottles. TrussFormer adds movement to these structures by placing linear actuators into them: either manually, wrapped in reusable components called assets, or by demonstrating the intended movement. TrussFormer verifies that the resulting structure is mechanically sound and will withstand the dynamic forces resulting from the motion. To fabricate the design, TrussFormer generates the underlying hinge system that can be printed on standard desktop 3D printers. We demonstrate TrussFormer with several example objects, including a 6-legged walking robot and a 4m-tall animatronics dinosaur with 5 degrees of freedom.”

The system adds linear actuators into rigid truss structures, known as variable geometry trusses, to initiate organic movement, which means they hinge around several points at once. One example that illustrates this is a static tetrahedron that, when an edge is switched out with a linear actuator, becomes a moving structure. Rotation is possible by introducing connections, or hinges, at the nodes.

The research team demonstrated the TrussFormer workflow on an animatronic model of a T-rex. First, the software designs the static structure shape with structurally stable primitives, such as octahedra and tetrahedra. With TrussFormer, there are three different ways to animate the structures:

1. Automated placement
2. Placing elements with pre-defined motion; known as assets
3. Manual placement

The first way is for beginners, while the third is for users actively acquiring engineering knowledge. In order to add movement through the ‘demonstrate movement’ tool, the T-rex head is pulled down; then, the system places an actuator that turns the body into a structure capable of bending down.

TrussFormer then verifies that the mechanism is structurally sound during a stability check across the structure’s various poses, so that users don’t produce invalid configurations.

“In the background, TrussFormer finds the safe range of expansion and contraction of the placed actuator by simulating the occurring forces in a range of positions,” the researchers explained on their HPI project page. “If there is a pose where the forces exceed the pre-determined breaking limits or the structure would tip over, TrussFormer sets the limits for the actuator so it will not extend beyond them.”

Once the animation pane is opened in the software’s toolbar, sliders can be used to manually control and try out the structure’s movement. Once the desired pose is found, users can add it to the animation timeline as a keyframe. This allows TrussFormer users to orchestrate how all of the actuators move with just a simple timeline and editor: for instance, a feeding behavior, where the T-rex opens its mouth, leans down, and waves its tail, can be easily programmed.

Once the user has defined the structure’s animation, TrussFormer then computes the dynamic forces. In the example of the T-rex body moving up and down, the long neck’s large acceleration leads to high inertial forces, which goes past the construction’s breaking limit and causes the structure to fail. It can be hard to realize this ahead of time, because often times inertial forces are far higher than the static load in a structure. That’s why the software automatically corrects the animation sequence – limiting either the range of movement or acceleration – so that the structure will be able to hold up.

The ‘fabricate’ button is pushed once users are satisfied with the design’s structure, movement, and animation. This will then start the hinge generation algorithm, which analyzes the motion of the structure and generates the correct geometries for 3D printable hubs and hinges; these come with imprinted IDs for easy assembly. For the T-rex, 42 hubs, with 135 hinging pieces, are exported.

The software exports the animation patterns as Arduino code, and finally outputs a specification file with the speed, motion range, and force of the actuators so users can “achieve the desired animation pattern.”

“TrussFormer helps users in the 3 main steps along the design process,” the researchers conclude. “(1) It enables users to animate large truss structures by adding linear actuators to them. It offers three tools for this purpose: manual actuator placement, placement of assets performing predefined motion, and creating motion by demonstration. (2) TrussFormer validates the design in real time against static forces, static forces across all poses, and dynamic forces. (3) TrussFormer automatically generates the necessary 3D printable hinges for fabricating the structure. Its algorithm determines the placement and configuration of the hinges and their exact dimensions.”

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[Images: Hasso-Plattner Institute]