Posts belonging to Category 3D printing

3D Printed Concrete Bridge

Today world’s first 3D printed reinforced, pre-stressed concrete bridge was opened. The cycle bridge is part of a new road around the village of Gemert, in the Netherlands. It was printed at Eindhoven University of Technology. With the knowledge the researchers gained in this project, they are now able to design even larger printed concrete structures.
The bridge is the first civil infrastructure project to be realized with 3D-concrete printing. The bridge is 8 meters long (clear span 6.5 meters) and 3.5 meters wide. As it is a ‘worlds first’, the developers did not take any chances and tested the bridge by putting a load of 5 tons on it, which is a lot more than the load the bridge will actually carry.


The bridge has to meet all regular requirements of course. It is designed to do its duty – to carry cyclists – for thirty years or more. With more cycles than people in the Netherlands, it is expected that hundreds of cyclists will ride over the printed bridge every day. It is part of a large road construction project, led by the company BAM Infra, and commissioned by the province of North-Brabant.
An important detail is that the researchers at Eindhoven University of Technology have succeeded in developing a process to incorporate steel reinforcement cable while laying a strip of concrete. The steel cable is the equivalent of the reinforcement mesh used in conventional concrete. It handles the tensile stress because concrete cannot deal with tensile stress adequately, but steel can.
One of the main advantages of printing concrete is that much less concrete is needed than in the conventional technique, in which a mold (formwork) is filled with concrete. By contrast, the printer deposits only the concrete where it is needed, which decreases the use of cement. This reduces CO2 emissions, as cement production has a very high carbon footprint.

Another benefit lies in the freedom of form: the printer can make any desired shape, whereas conventional concrete shapes tend to be unwieldy in shape due to use of formwork. Concrete printing also enables a much higher realization speed. No formwork structures have to be built and dismantled, and reinforcement mesh does not have to be put in place separately. Overall, the researchers think the realization will eventually be roughly three times faster than conventional concrete techniques.


How To Forge Graphene In 3D Shape

The wonder material graphene gets many of its handy quirks from the fact that it exists in two dimensions, as a sheet of carbon only one atom thick. But to actually make use of it in practical applications, it usually needs to be converted into a 3D form. Now, researchers have developed a new and relatively simple way to do just that, using lasers to “forge” a three-dimensional pyramid out of graphene.

This isn’t the first time graphene has been given an extra dimension. In 2015, researchers from the University of Illinois molded graphene into 3D structures by layering it onto shaped substrates, and early this year MIT scientists found that tubes of the stuff could be shaped into 3D coral-like structures 10 times stronger than steel but just five percent as dense. Rice University researchers have also recently made graphene foam and reinforced it with carbon nanotubes.

But this new technique, developed by researchers in Finland and Taiwan, might be an easier and faster method to make 3D graphene. By focusing a laser onto a fine point on a 2D graphene lattice, the graphene at that spot is irradiated and bulges outwards. A variety of three-dimensional shapes can be made by writing patterns with the laser spot, with the height of the shape controlled by adjusting the irradiation dose at each particular point.

The team illustrated that technique by deforming a sheet of graphene into a 3D pyramid, standing 60 nm high. That sounds pretty tiny, but it’s 200 times taller than the graphene sheet itself.

We call this technique optical forging, since the process resembles forging metals into 3D shapes with a hammer,” says Mika Pettersson, co-author of the study. “In our case, a laser beam is the hammer that forges graphene into 3D shapes. The beauty of the technique is that it’s fast and easy to use; it doesn’t require any additional chemicals or processing. Despite the simplicity of the technique, we were very surprised initially when we observed that the laser beam induced such substantial changes on graphene. It took a while to understand what was happening.”

The researchers initially assumed that the laser had “doped” the graphene, introducing impurities into the material, but after further examination they found that wasn’t the case.

When we first examined the irradiated graphene, we were expecting to find traces of chemical species incorporated into the graphene, but we couldn’t find any,” comments Wei Yen Woon, co-author of the study. “After some more careful inspections, we concluded that it must be purely structural defects, rather than chemical doping, that are responsible for such dramatic changes on graphene.

The scientists explain that the optically forged graphene is structurally sound, highlighting its potential for building 3D architectures out of the material for a wide range of applications. In this form, the graphene has different electronic and optical properties from its 2D counterpart.

The research was published in the journal Nano Letters.

Source: Academy of Finland

Robots With The Sense Of Touch

A team of researchers from the University of Houston (UH) has reported a breakthrough in stretchable electronics that can serve as an artificial skin, allowing a robotic hand to sense the difference between hot and cold, while also offering advantages for a wide range of biomedical devices.

Cunjiang Yu, Bill D. Cook Assistant Professor of mechanical engineering and lead author for the paper, said the work is the first to create a semiconductor in a rubber composite format, designed to allow the electronic components to retain functionality even after the material is stretched by 50 percent. The semiconductor in rubber composite format enables stretchability without any special mechanical structure. Yu noted that traditional semiconductors are brittle and using them in otherwise stretchable materials has required a complicated system of mechanical accommodations. “That’s both more complex and less stable than the new discovery, as well as more expensive.”

Our strategy has advantages for simple fabrication, scalable manufacturing, high-density integration, large strain tolerance and low cost,” he said.

Yu and the rest of the team – co-authors include first author Hae-Jin Kim, Kyoseung Sim and Anish Thukral, all with the UH Cullen College of Engineering – created the electronic skin and used it to demonstrate that a robotic hand could sense the temperature of hot and iced water in a cup. The skin also was able to interpret computer signals sent to the hand and reproduce the signals as .

The robotic skin can translate the gesture to readable letters that a person like me can understand and read,” Yu said.

The work is reported in the journal Science Advances.


China, Global Leader In NanoScience

Mobile phones, computers, cosmetics, bicyclesnanoscience is hiding in so many everyday items, wielding a huge influence on our lives at a microscale level. Scientists and engineers from around the world exchanged new findings and perceptions on nanotechnology at the recent 7th International Conference on Nanoscience and Technology (ChinaNANO 2017) in Beijing last week. China has become a nanotechnology powerhouse, according to a report released at the conference. China’s applied nanoscience research and the industrialization of nanotechnology have been developing steadily, with the number of nano-related patent applications ranking among the top in the world.

According to Bai Chunli, president of the Chinese Academy of Sciences (CAS), China faces new opportunities for nanoscience research and development as it builds the National Center for Nanoscience and Technology  (NCNST) and globally influential national science centers.

We will strengthen the strategic landscape and top-down design for developing nanoscience, which will contribute greatly to the country’s economy and society,” said Bai.

Nanoscience can be defined as the study of the interaction, composition, properties and manufacturing methods of materials at a nanometer scale. At such tiny scales, the physical, chemical and biological properties of materials are different from those at larger scales — often profoundly so.

For example, alloys that are weak or brittle become strong and ductile; compounds that are chemically inert become powerful catalysts. It is estimated that there are more than 1,600 nanotechnology-based consumer products on the market, including lightweight but sturdy tennis rackets, bicycles, suitcases, automobile parts and rechargeable batteries. Nanomaterials are used in hairdryers or straighteners to make them lighter and more durable. The secret of how sunscreens protect skin from sunburn lies in the nanometer-scale titanium dioxide or zinc oxide they contain.

In 2016, the world’s first one-nanometer transistor was created. It was made from carbon nanotubes and molybdenum disulphide, rather than silicon.
Carbon nanotubes or silver nanowires enable touch screens on computers and televisions to be flexible, said Zhu Xing, chief scientist (CNST). Nanotechnology is also having an increasing impact on healthcare, with progress in drug delivery, biomaterials, imaging, diagnostics, active implants and other therapeutic applications. The biggest current concern is the health threats of nanoparticles, which can easily enter body via airways or skin. Construction workers exposed to nanopollutants face increased health risks.

The report was co-produced by Springer Nature, National Center for Nanoscience and Technology (NCNST) and the National Science Library of the Chinese Academy of Sciences (CAS).


Move And Produce Electricity To Power Your Phone

Imagine slipping into a jacket, shirt or skirt that powers your cell phone, fitness tracker and other personal electronic devices as you walk, wave and even when you are sitting down. A new, ultrathin energy harvesting system developed at Vanderbilt University’s Nanomaterials and Energy Devices Laboratory has the potential to do just that. Based on battery technology and made from layers of black phosphorus that are only a few atoms thick, the new device generates small amounts of electricity when it is bent or pressed even at the extremely low frequencies characteristic of human motion.


In the future, I expect that we will all become charging depots for our personal devices by pulling energy directly from our motions and the environment,” said Assistant Professor of Mechanical Engineering Cary Pint, who directed the research.
This is timely and exciting research given the growth of wearable devices such as exoskeletons and smart clothing, which could potentially benefit from Dr. Pint’s advances in materials and energy harvesting,” observed Karl Zelik, assistant professor of mechanical and biomedical engineering at Vanderbilt, an expert on the biomechanics of locomotion who did not participate in the device’s development.

Doctoral students Nitin Muralidharan and Mengya Lic o-led the effort to make and test the devices. When you look at Usain Bolt, you see the fastest man on Earth. When I look at him, I see a machine working at 5 Hertz, said Muralidharan.

The new energy harvesting system is described in a paper titled “Ultralow Frequency Electrochemical Mechanical Strain Energy Harvester using 2D Black Phosphorus Nanosheets” published  by the journal ACS Energy Letters.


How To Strengthen 3-D Printed Parts

From aerospace and defense to digital dentistry and medical devices, 3-D printed parts are used in a variety of industries. Currently, 3-D printed parts are very fragile and traditionally used in the prototyping phase of materials or as a toy for display. A doctoral student in the Department of Materials Science and Engineering at Texas A&M University has pioneered a countermeasure to transform the landscape of 3-D printing today.

Brandon Sweeney and his advisor Dr. Micah Green, associate professor in the Department of Chemical Engineering, discovered a way to make 3-D printed parts stronger and immediately useful in real-world applications. Sweeney and Green applied the traditional welding concepts to bond the submillimeter layers in a 3-D printed part together, while in a microwave.

I was able to see the amazing potential of the technology, such as the way it sped up our manufacturing times and enabled our CAD designs to come to life in a matter of hours,” Sweeney said. “Unfortunately, we always knew those parts were not really strong enough to survive in a real-world application.

3-D printed objects are comprised of many thin layers of materials, plastics in this case, deposited on top of each other to form a desired shape. These layers are prone to fracturing, causing issues with the durability and reliability of the part when used in a real-world application, for example a custom printed medical device. “I knew that nearly the entire industry was facing this problem,” Sweeney said. “Currently, prototype parts can be 3-D printed to see if something will fit in a certain design, but they cannot actually be used for a purpose beyond that.”

When Sweeney started his doctorate, he was working with Green in the Department of Chemical Engineering at Texas Tech University. Green had been collaborating with Dr. Mohammad Saed, assistant professor in the electrical and computer engineering department at Texas Tech, on a project to detect carbon nanotubes using microwaves. The trio crafted an idea to use carbon nanotubes in 3-D printed parts, coupled with microwave energy to weld the layers of parts together.

The basic idea is that a 3-D part cannot simply be stuck into an oven to weld it together because it is plastic and will melt,” Sweeney said. “We realized that we needed to borrow from the concepts that are traditionally used for welding parts together where you’d use a point source of heat, like a torch or a TIG welder to join the interface of the parts together. You’re not melting the entire part, just putting the heat where you need it.” The technology is patent-pending and licensed with a local company, Essentium Materials.

The team recently published a paper “Welding of 3-D Printed Carbon Nanotube-Polymer Composites by Locally Induced Microwave Heating,” in Science Advances.


Perovskite Solar Cells Conversion Efficiency Rises Up To 20%

A new low-temperature solution printing technique allows fabrication of high-efficiency perovskite solar cells with large crystals intended to minimize current-robbing grain boundaries. The meniscus-assisted solution printing (MASP) technique boosts power conversion efficiencies to nearly 20 percent by controlling crystal size and orientation.

The process, which uses parallel plates to create a meniscus of ink containing the metal halide perovskite precursors, could be scaled up to rapidly generate large areas of dense crystalline film on a variety of substrates, including flexible polymers. Operating parameters for the fabrication process were chosen by using a detailed kinetics study of perovskite crystals observed throughout their formation and growth cycle.

We used a meniscus-assisted solution printing technique at low temperature to craft high quality perovskite films with much improved optoelectronic performance,” said Zhiqun Lin, a professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. “We began by developing a detailed understanding of crystal growth kinetics that allowed us to know how the preparative parameters should be tuned to optimize fabrication of the films.”

The new technique is reported in the journal Nature Communications.


3-D Printed Graphene Foam

Nanotechnologists from Rice University and China’s Tianjin University have used 3-D laser printing to fabricate centimeter-sized objects of atomically thin graphene. The research could yield industrially useful quantities of bulk graphene and is described online in a new study in the American Chemical Society journal ACS Nano.

Laser sintering was used to 3-D print objects made of graphene foam, a 3-D version of atomically thin graphene. At left is a photo of a fingertip-sized cube of graphene foam; at right is a close-up of the material as seen with a scanning electron microscope

This study is a first of its kind,” said Rice chemist James Tour, co-corresponding author of the paper. “We have shown how to make 3-D graphene foams from nongraphene starting materials, and the method lends itself to being scaled to graphene foams for additive manufacturing applications with pore-size control.”

Graphene, one of the most intensely studied nanomaterials of the decade, is a two-dimensional sheet of pure carbon that is both ultrastrong and conductive. Scientists hope to use graphene for everything from nanoelectronics and aircraft de-icers to batteries and bone implants. But most industrial applications would require bulk quantities of graphene in a three-dimensional form, and scientists have struggled to find simple ways of creating bulk 3-D graphene.

For example, researchers in Tour’s lab began using lasers, powdered sugar and nickel to make 3-D graphene foam in late 2016. Earlier this year they showed that they could reinforce the foam with carbon nanotubes, which produced a material they dubbed “rebar graphene” that could retain its shape while supporting 3,000 times its own weight. But making rebar graphene was no simple task. It required a pre-fabricated 3-D mold, a 1,000-degree Celsius chemical vapor deposition (CVD) process and nearly three hours of heating and cooling.  “This simple and efficient method does away with the need for both cold-press molds and high-temperature CVD treatment,” said co-lead author Junwei Sha, a former student in Tour’s lab who is now a postdoctoral researcher at Tianjin. “We should also be able to use this process to produce specific types of graphene foam like 3-D printed rebar graphene as well as both nitrogen- and sulfur-doped graphene foam by changing the precursor powders.” Sha and colleagues conducted an exhaustive study to find the optimal amount of time and laser power to maximize graphene production. The foam created by the process is a low-density, 3-D form of graphene with large pores that account for more than 99 percent of its volume.

The 3-D graphene foams prepared by our method show promise for applications that require rapid prototyping and manufacturing of 3-D carbon materials, including energy storage, damping and sound absorption,” said co-lead author Yilun Li, a graduate student at Rice.


Cellulose-based Ink For 3D Printing

Empa (Switzerland) researchers have succeeded in developing an environmentally friendly ink for 3D printing based on cellulose nanocrystals. This technology can be used to fabricate microstructures with outstanding mechanical properties, which have promising potential uses in implants and other biomedical applications.

Cellulose, along with lignin and hemicellulose, is one of the main constituents of wood. The biopolymer consists of glucose chains organized in long fibrous structures. In some places the cellulose fibrils exhibit a more ordered structure.

In order to produce 3D microstructured materials for composite applications, for instance, Empa researchers have been using a 3D printing method called “Direct Ink Writing” for the past year. During this process, a viscous substance – the printing ink – is squeezed out of the printing nozzles and deposited onto a surface, pretty much like a pasta machine. Empa researchers Gilberto Siqueira and Tanja Zimmermann from the Laboratory for Applied Wood Materials have now succeeded, together with Jennifer Lewis from Harvard University and André Studart from the ETH Zürich, in developing a new, environmentally friendly 3D printing ink made from cellulose nanocrystals (CNC).
The places with a higher degree of order appear in a more crystalline form. And it is these sections, which we can purify with acid, that we require for our research“, explains Siqueira. The final product is cellulose nanocrystals, tiny rod-like structures that are 120 nanometers long and have a diameter of 6.5 nanometers. And it is these nanocrystals that researchers wanted to use to create a new type of environmentally friendly 3D printing ink.They have now succeeded that  their new inks contain a full 20 percent CNC.

The biggest challenge was in attaining a viscous elastic consistency that could also be squeezed through the 3D printer nozzles“, says Siqueira. The ink must be “thick” enough so that the printed material stays “in shape” before drying or hardening, and doesn’t immediately melt out of shape again.


Metal 3D Printing Withstands Extreme Pressure And Heat

3D printed metal turbine blades able to withstand extreme pressure have been successfully tested by Siemens. It opens the way to develop high pressure components for power generators and other industries, such as aeronautics. These blades can survive temperatures above 1,250 Celsius and pressures similar to the weight of a double-decker bus.


“To have this rotating part running is a breakthrough because it is submitted to these extreme loading… It rotates with 13,600 rotations-per-minute which means it is the most highly loaded component in the whole gas turbine. So this blade that weighs 180 grams will weigh 11 tonnes while rotating with this speed,” says Jenny Nilsson, Team leader for additive manufacturing at Siemens.

Last year Siemens bought British-based Material Solutions, where the metal-based printing is being perfected. A computer-aided design model is first sent to one of these machines. Precision lasers are then fired at a thin layer of metal powder.

This is the nickel superalloy powder. This metallic powder is deposited in 20 micron layer thickness and then the laser melts the part,“explains Clotilde Ravoux, system engineer at Material Solutions.

Ultra-thin layers are added one by one, building up the part. Testing is ongoing and Siemens can’t say when these blades will be commercially produced. But they say it reduces the design-to-testing time from years to months.  “When you apply casting procedures you will probably take one to one and a half years to provide you with these blades because of their long lead-time for tooling. And by applying additive manufacturing we could significantly shorten lead time by down to three months,” adds  Christoph Haberland, manufacturing engineering.

General Electric introduced its first 3D-printed aircraft engine component into service last July. While Boeing is using metal-based 3D printing to drastically cut the production costs of its 787 Dreamliner.


Super-material Bends, Shapes And Focuses Sound Waves

These tiny 3D-printed bricks could one day allow people to create their own acoustics. That’s the plan of scientists from the universities of Bristol and Sussex. They’ve invented a metamaterial which bends and manipulates sound in any way the user wants. It’s helped scientists create what they call a ‘sonic alphabet‘.


We have discovered that you just need 16 bricks to make any type of sound that you can imagine. You can shape the sound just with 16 of them, just like you create any words with just 26 letters,” says Dr. Gianluca Memoli, researcher at Interact Lab at University of Sussex.

DIY kits like this, full of batches of the 16 aural letters, could help users create a sound library, or even help people in the same car to hear separate things.

With our device what you can have is you can strap a static piece on top of existing speakers and they can direct sound in two different directions without any overlap. So the passengers can hear completely different information from the driver,” explains Professor Sri Subramanian Interact Lab at University of Sussex. This technology is more than five years away, but smaller versions could be used to direct medical ultrasound devices far sooner.  “In a year we could have a sleeve that we can put on top of already existing projects in the market and make them just a little bit better. For example, we can have a sleeve that goes on top of ultrasound pain relieving devices that are used for therapeutic pain,” he adds.
Researchers say spatial sound modulators will one day allow us to perform audible tasks previously unheard of.


3D Printing Art And Design in Paris

Do you plan  to travel to Paris? In this case do not miss to visit the Centre Pompidou,  this huge museum, located in the center of Paris and dedicated to modern Art.  You can assist to  “Mutations/Créations“: a new event decidedly turned towards the future and the interaction between digital technology and creation; a territory shared by art, innovation and science.


Drawing on all the disciplines in a mix of research, art and engineering, the first edition of this annual event calls upon music, design and architecture. It consists of two exhibitions (“Imprimer le monde“ and “Ross Lovegrove“), an Art/Innovation Forum entitled “Vertigo“, and various study days and get-togethers. Each year, thematic and monographic exhibitions will be staged around meetings and workshops that turn the Centre Pompidou into an “incubator“: a place for demonstrating prototypes, carrying out artistic experiments in vivo, and talking with designers. This platform will also be a critical observatory and a tool for analysing the impact of creation on society. How have the various forms of creation begun using digital technologies to open up new industrial perspectives? How do they question the social, economic and political effects of these industrial developments, and their ethical limits? What formal transformations have come about in music, art, design and architecture with regard to technical and scientific progress?

In the same space,  you can see a  new retrospective devoted to British designer Ross Lovegrove, which shows how the artist has introduced a fresh dialogue between nature and technology, where art and science converge. He employs a “holistic“ idea of design through a visionary practice that began incorporating digital changes during the 1990s, rejecting the productivism of mass industry and replacing it with a more economical approach to materials and forms. This exhibition emphasises the role of design in the postindustrial era, now that we are seeing a significant shift from mechanics to organics: a changeover symptomatic of our times, which these “digital forms“ endeavour to highlight.