3d-printed-artificial-coral-designed-to-bolster-endangered-reefs

Coral reefs are one of the nature eco-systems that are being affected by global climate change, and scientists are seeking ways to help save the marine life that depends on them for sustenance.

One solution to help improve the health of coral reefs comes from researchers at the University of Delaware, who have found that 3D-printed coral models can supplement depleted coral resources and still help maintain a healthy marine system.

artificial coral, endangered reefs, University of Delaware, Fiji, global climate change

Shown here are 3D-printed coral models of Acropora formosa, a type of coral found in the Indian and Pacific Oceans. The 3D printed models of differing complexity were secured to an area of a reef with low-complexity, then observed to understand which habitat the fish preferred. (Source: University of Delaware)

The team, led by Associate Professor Danielle Dixson, came upon their solution while researching another idea, she told Design News. Dixson is a researcher in the university’s College of Earth, Ocean and Environment’s School of Marine Science and Policy.

“We were initially interested in investigating the role of topographic complexity–how many tiny holes there are for animals to hide in–on coral reefs,” said Dixson. “To do this study, we needed to come up with a way to create more and less topographically complex structures to test our research hypothesis. Using 3D printing allowed us to image a real coral and then add or subtract branches, keeping the relative size the same but changing how complex the print was.”

The team later realized their invention could help solve a real-world problem—to help some of the fish in coral reefs still have places to live in safety. “Coral reefs are under threat from a number of different environmental stressors,” including climate change, tourism damage and boat damage, hurricanes etc.,” said Dixson. “Either way, reefs are often left after a stressful event with less topographic complexity.”

Without this protection, these marine creatures could die prematurely. “Topographic complexity is really important because it provides space for small fish, especially juveniles, and invertebrates to live in,” said Dixson.

A New Solution

Dixon noted there already is a solution being used to replace damaged parts of reefs, but they each have their own drawbacks. “Current restoration methods rely on outplanting coral fragments into reefs that have begun to degrade,” said Dixon.“While there are benefits to this, the coral fragments are often small, and the corals that are fragmented are typically the species that have the best survivorship and the best growth rate after outplanting. These are not necessarily the most important corals or the most structurally complex corals.”

The process also is extremely time consuming because corals growth very slowly, so the fragments need a lot of time to reach a size that can help organisms on the reef, she said. “The 3D prints solve these issues,” said Dixson.

The team tested their solution with damselfish that live in the tropical waters off the island of Fiji. What they found is that 3D-printed objects do not impact the behavior of the damsel fish or the survival of a settling stony coral.

They fabricated their 3D coral in a 3D printer by replicating a coral skeleton using 50 iPhone images of the coral taken from all angles. They printed four different artificial coral models from low-cost, widely available filaments, including polyester and two biodegradable materials–one made from cornstarch and another made from cornstarch combined with stainless steel powder.

The team published a paper on their work in the journal PLOS.

Field Tests and Fish Behavior

In their tests, Dixson and her team discovered that fish showed no preference between materials used to 3D-print artificial corals. This allowed researchers to use a biodegradable corn-based PLA, which naturally degrades over time. The team deployed artificial coral made of this material to help replenish the coral on the Fiji reef, where they are currently observing the results.

The solution is meant to be temporary and promote the growth of natural coral, with the artificial material eventually dissolving and giving way to new corals. “The corals are able to have real coral larvae settle on them and grow into corals, so it is our hope and hypothesis that the corals could be put on a reef and would naturally become covered with live corals,” said Dixson. “Live corals take a long time to grow into a substantial structure, so while they are growing the 3D artificial corals can work as a temporary refuge for fish and invertebrates that rely on complex habitat.”

The team is currently conducting field trials to examine more closely how animals interact with the prints in a natural setting, and expect to base future research using artificial coral on these results.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.


DesignCon 2020 25th anniversary Logo

January 28-30: North America’s largest chip, board, and systems event, DesignCon, returns to Silicon Valley for its 25th year! The premier educational conference and technology exhibition, this three-day event brings together the brightest minds across the high-speed communications and semiconductor industries, who are looking to engineer the technology of tomorrow. DesignCon is your rocket to the future. Ready to come aboard? Register to attend!

5-tips-to-reduce-adhesive-cycle-times

Many industrial bonding processes use slow-curing two-component adhesives (about 24 hours to final strength) or heat-curing one-component adhesives (about 0.5 to 1.5 hours to final strength, without counting the time for heating the components). When the focus is on reducing cycle times, light-curing products are primarily considered. Some of these products cure in less than one second.

In the past, at least one of the components to be joined had to be optically transparent, allowing light energy to reach the adhesive and trigger the curing mechanism. This reduced the choice of materials to a few types of plastic and glass. Today, new adhesive chemistries paired with multi-stage curing processes allow cycle times of many other bonding processes, for materials like metals and opaque plastics, to be shortened significantly.

Light Fixation for Structural Bonding

If structural bonds are exposed to greater static dynamic loads or increased temperatures, purely heat-curing epoxy resin adhesives should be used. However, such products have not been available with light-curing properties. As a result, fixing devices were frequently used to hold in position the components in the production lines and during oven curing.

Recently, light-fixable products have become available for such applications. Their two-stage light and heat-curing mechanism simplifies and accelerates the production process. The joined components are first prefixed at the adhesive fillet, which takes one to five seconds depending on the intensity of the UV light. This eliminates the need for holding devices along with time-consuming and costly assembly, disassembly and cleaning. The epoxy resin reaches its full strength with the subsequent, and still necessary, step of heat curing, which usually takes 20 minutes at 130 °C or even less at higher temperatures.

Light-fixable structural adhesives, production of electric motors, DELO
Light-fixable structural adhesives are used, for example, in the production of electric motors (Image source: DELO)

The final strength on aluminum is 60 MPa, on PA6 it is 30 MPa. 60 MPa correspond to a force of 1.2 tons on the surface of a penny. In addition, they have similarly high thermal and chemical resistance as purely heat-curing adhesives.

Using the Diversity of Dual-Curing Adhesives

When two components are bonded, it is important that all the adhesive is fully cured. If the light reaches only part of the adhesive, it will remain liquid in the so-called shadowed areas. On the one hand, no adhesion is built up in those areas. On the other hand, there is a risk of corrosion. If speed requirements suggest the use of light-curing adhesives, shadowed areas should be avoided starting from the design stage.

For the many cases where this is not possible or possible only with great difficulty, there are numerous new dual-curing adhesives that reliably build up adhesion even in shadowed areas. In addition to light, they feature a second curing mechanism that can be triggered by air humidity, exclusion of oxygen or heat. Each option meets different requirements and opens up other production processes.

Dual-curing adhesives offer the benefits of light-curing products without compromising on reliability, bond strength and processing quality. They also ensure that the adhesive in the finished product is fully cured and permit maximum bonding precision in complex modules. They offer a high degree of flexibility in production, giving users more freedom in designing assemblies and developing their production processes.

Light Curing for Black Adhesives

If light-curing products are used, it goes without saying that the adhesive itself must also be translucent, since the photoinitiators in the entire adhesive layer must decompose to start the crosslinking reaction. Therefore, light curing in combination with black encapsulants and adhesives often used for optical purposes or security reasons should, by definition, be a contradiction, because black absorbs most of the light. But it’s not.

There are black adhesives that cure very well in layer thicknesses of up to 500 µm. In addition to their light-curing component, they also contain a small humidity-curing portion, which triggers crosslinking even in shadowed areas. These products typically provide good strength. The flexibility offered by their acrylate chemistry, exhibits high elongation at tear and very good tension-equalizing properties.

Light-fixable structural adhesives, production of electric motors, DELO, black adhesives, light-cured
Even black adhesives can be light-cured (Image source: DELO)

Preactivation: Light Curing Even for Opaque Components

If opaque materials are to be bonded and there is no fillet weld that can be reached by light, as is often the case in the automotive industry that uses decorative elements made of dark plastics or chrome, light curing alone is impossible due to the opacity. However, users may use adhesives that can be preactivated by light in order to bond non-transparent components and still benefit from rapid curing. A conventional light curing procedure includes dispensing, joining and irradiation. In contrast, when using a preactivation process, the complete adhesive is applied to one side of the two components and is irradiated with light immediately before joining the components.

The special feature of this process is that the adhesive still remains liquid after the brief exposure to light, allowing the components to be joined and adjusted during a period called “open time,” after which the adhesive cures within a few minutes without further light irradiation.

Light-fixable structural adhesives, production of electric motors, DELO

Light-fixable structural adhesives, production of electric motors, DELO, black adhesives, light-cured

Light-fixable structural adhesives, production of electric motors, DELO, black adhesives, light-cured
In contrast to the conventional light-curing steps of dispensing, joining, and irradiating, the order for preactivation is dispensing, irradiating, and joining (Image source: DELO)

High-Intensity LED Lamps

LED technology has continued to evolve in recent years, especially with regard to the intensities achieved. Good area curing lamps now offer values ​​of more than 1,000 mW/cm² at a distance of 2 mm. In most cases, conversion to modern, high-intensity LED lamps can significantly accelerate the light-curing process, since more energy reaches the adhesive.

This is advantageous even if the maximum intensity of the adhesive – the threshold from which higher intensity no longer leads to faster curing – is lower than the lamp’s intensity. This applies to components with poor transmittance, which absorb light energy and prevent the full intensity from reaching the adhesive.

Light-fixable structural adhesives, production of electric motors, DELO, black adhesives, light-cured
High-intensity LED curing lamps not only accelerate curing, but also provide more flexibility in production (Image source: DELO)

In addition, the use of high-intensity curing lamps allows larger exposure distances, which is useful for difficult geometries such as holes or when the joined materials are a little further from the light source due the component design or the assembly line layout. In these cases too, sufficient energy is available thanks to the lamp’s high intensity levels, and the adhesive cures within seconds.

Even when full intensity is not needed, there is an advantage: Users may reduce energization of the powerful lamps. This protects the LEDs and extends their already very long lifetime of typically 20,000 hours.

Bernd Scholl is the head of product technology at DELO.

print-in-place-electronics-pave-way-for-electronic-tattoos,-personal-biosensors

Printable electronics are seen as the wave of the future for electronic devices, as form factors go smaller, more flexible, and even flatter.

Researchers at Duke University have made a breakthrough in this endeavor with the invention of what they said is the first simple technique for printing electronics in place, paving the way for applications such as electronic tattoos and bandages.

electronic tattoos, print-in-place electronics, Duke University, low-cost electronics fabrication process
Two electronically active leads directly printed along the underside of Duke graduate student Nick Williams’s pinky successfully light up an LED when a voltage is applied. The process is part of a method developed by researchers there to fabricate print-in-place electronics. (Image source: Duke University)

A team led by Aaron Franklin, the a professor of electrical and computer engineering at Duke, developed the fully print-in-place method, which researchers said is gentle enough to work on delicate surfaces including paper and human skin.

“Most means of making electrics require many, many processing steps,” Nick Williams, a Duke PhD student of electrical and computer engineering, explained to Design News. “Even with simple, low-cost electronics fabrication process, like printed electronics, there are many further steps after deposition that are required to achieve the desired properties.”

The process the team designed, however, is far simpler, and more of a “step towards the fully printed ideal that everyone expects when we think of printed electronics,” he told Design News.

“We have developed the first recorded transistor that has been completely fabricated in a printer,” Williams told us. “The only procedure we did was a quick rinse. All of this could be automated to take humans completely out of the process, and a long-term the goal would be for a black-box fabrication of electronics where you insert your desired substrate and you can remove a fully functioning circuit.”

Solving Previous Challenges

Researchers developed a number of inks to get the desired material properties for their method and result, Williams said. They also aimed to solve a historical challenge with developing printed electronics, which is that they are unstable in air, decreasing their utility, he said.

To do this, the team ultimate used two-dimensional materials to achieve the desired materials properties at room temperature, developing a hexagonal boron nitride ink that allowed the team to print a stable dielectric material at low temperature, Williams told Design News.  

“The 2D structure of hexagonal boron nitride allows for this material to be insulating immediately after printing without any further post-processing,” he explained to us.

The team also developed a silver nanowire ink that is immediately conductive after printing, which allowed the team to print at room temperature and achieve the same levels of conductivity, Williams said.

“Almost all other inks require sintering at temperatures above 150 °C,” he told us. Researchers published papers online about their work both in the journal Nanoscale and in the journal ACS Nano.

Uses and Future Design

Researchers envision that their work can pave the way for printers that can develop print-in-place electronics and might become as ubiquitous as 3D printers are becoming today, Williams said.

“Children are raised now knowing that they can print almost any shape they want,” he told Design News. “We would like to expand that to include the intimate incorporation of electronics.”

The research also paves the way for new designs for medical applications, including customizable printed electronic tattoos used for healthcare purposes, Williams said.

“These could be used for short term, non-invasive monitoring of patient vitals and well-being,” he told Design News, adding that, “really, the possibilities [for applications] are endless.”

Researchers plan to continue to develop the technology and make improvements to its performance to “reduce the processing steps to make these devices as easy to fabricate as possible,” Williams told us. The team also aims to expand the scope of applications for their work, he said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

soft-actuators-make-robots-nimble-and-less-unwieldy

With robots eyed to work alongside humans and perform more complex tasks in the future, researchers have been working to create soft components and actuators that can meet these requirements.

Some of the latest research in this area is from engineers at the University of California (UC) San Diego, which have developed new, tubular soft actuators with electrically controlled movements that allows them to be integrated with small electronic components, they said.

actuators, soft robots, University of California San Diego, soft materials, highly deformable structures, tubular actuators, multidirectional bending deformation
Electrically controlled, untethered soft robot built out of four soft tubular actuators, a microcontroller, and battery. The robot can be programmed to walk or carry an object. (Image source: David Baillot/UC San Diego Jacobs School of Engineering)

Soft actuators are those that are made from soft materials or highly deformable structures, and their benefit is that they have a higher degree of freedom as well as can have “friendly” interaction with humans, said Qiguang He, a mechanical and aerospace engineering Ph.D. student at the university’s Jacobs School of Engineering. He worked on the project, which was led by UC San Diego mechanical and aerospace engineering Professor Shengqiang Cai.

The actuators the team designed are simple tubular actuators that allow for multidirectional bending deformation as well as homogeneous contraction, he told Design News.

“This unique character enable this tubular actuator can be applied to diverse engineering applications such as soft gripper and walking robot,” He told us.

Battle of the Bulk

While researchers have made significant advancements in developing soft actuators,  they are still controlled by pumping either air or fluids through chambers inside of the components, researchers said. To build robots with these actuators, then, requires the devices to be tethered to pumps, large power sources, and other specialized equipment, which creates bulk and makes them rather unwieldy, they said.

Controlling actuators with electricity allows scientists to build robots that lose some of this bulk, making them more streamlined and user-friendly, He said.

“We can use relatively low electrical potential (1.5 V to 3 V) to activate the large deformation of our soft actuator, [so] we do not require additional bulky pumps, valves, and voltage amplifiers except commercial electrical components like controller and battery, which greatly simplifies the whole system,” he told Design News.

Researchers achieved this by creating actuators from a type of material used for artificial muscles in robots, called liquid crystal elastomers (LCEs) that are composed of liquid-crystal molecules embedded in a stretchy polymer network. These materials change shape, move, and contract in response to stimuli such as heat or electricity, which is similar to how muscles in the human body contract in response to nerve signals, researchers said.

Material Consideration

To construct each actuator, engineers sandwiched three heating wires between two thin films of liquid crystal elastomer and then rolled the material into a tube, which is pre-stretched and exposed to UV light.

Key to the actuator’s design is that each heating wire can be controlled independently to make the tube bend in six different directions, researchers said.

When an electric current is passed through one or two of the wires, it heats up part of the tube and makes it bend in the direction of those wires. Passing a current through all three wires makes the entire tube contract, which shortens its length. If the electricity is turned off, it allows the tube to slowly cool down and return to its original shape, researchers said.

“Through locally controlling certain part of LCE, local contraction can be generated,” He told Design News. “If one heating wire is applied to the electrical potential, the multidirectional bending movement can be realized. If all heating wires are applied to electrical potential, homogeneous contraction can be generated.”

Researchers published a paper on their work in the journal Science Advances.

To prove their concept, engineers used these new actuators to build two robots—a soft, battery-powered robot that can walk untethered on flat surfaces and move objects, and a soft gripper that can grasp and pick up small objects.

Researchers plan to continue their work to develop actuators that can move faster. The current actuators take about 30 seconds to fully bend and contract, and up to four minutes to return to their original shapes. Ultimately, researchers want actuators that can contract and relax as quickly as human muscles, He said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

silk-can-be-made-into-shape-changing,-reusable-clothing

Researchers at Tufts University School of Engineering have designed new silk materials that can wrinkle into highly detailed patterns for next-generation smart clothing and optical applications. According to the researchers, the patterns can be in the form of words, textures, and even images as intricate as QR codes and fingerprints.

The transformation is also reversable, so the silk can be reused. “But beyond the novelty of reversible printing, there are many other functional applications that the silk patterning technology could provide,” Yu Wang, a post-doctoral fellow in the Tufts University School of Engineeringn noted in a press statement.

These applications are numerous, Wang said. They include materials with tunable optical properties, such as those that involve the use of dopants, allowing the patterned fabric to absorb or emit different wavelengths of light and energy, or exhibit patterns only from specific angles.

Other applications, according to the researchers, include next-generation textiles that can modulate their thermal properties to change and control the amount of heat they let through. And, since silk fibers are biocompatible, the material also could be used in biomedical applications.

The team published a paper on their work in the journal Proceedings of the National Academy of Science.

Wrinkles and Patterns

Silk Materials, Wrinkle on Demand, Reverse Printing, Re-Use, Tufts University, next-generation smart clothing, optical applications

Researchers at Tufts University have developed a silk material that can wrinkle into detailed patterns. Passing a voltage across a heating element connected to the silk bilayer expands the material to smooth out any patterns (left). Cutting off voltage allows material to cool and the high resolution wrinkle pattern appears (right). (Image source: Tufts University)

The materials function by taking advantage of the natural ability of silk fiber proteins, or fibroin, to change form in response to external conditions – including exposure to water vapor, methanol vapor, and UV radiation, said Wang.

“We can print patterns of remarkably high resolution in the silk – and we even showed that we can pick up the moisture pattern left by a fingerprint,” Wang said in a press statement.

Indeed, liquid is a key component to the material, the researchers said. They realized that water and methanol vapor, for example, can soak into the fibers and interfere with hydrogen bond cross links in the silk fibroin. This causes it to partially “unravel” and release tension in the fiber, Wang said.

The team manufactured a silk surface from dissolved fibroin by depositing it onto a thin plastic membrane comprised of PDMS. They put it through a cycle of heating and cooling, which caused the silk surface of the silk/PDMS layer to fold into nanotextured wrinkles because of their different mechanical properties.

Once these wrinkles were formed, the Tufts researchers found that exposing any part of the surface to water or methanol vapor causes the fibers to relax and the wrinkles to flatten. The smooth surface resulting from this transformation transmits more than 80% of light, while the wrinkled surface only allows 20% or less through. This contrast allows for perception of a printed pattern.

The team found that they also can create patterns in the silk by depositing water using inkjet printing, with resolution determined by the nozzle diameter of the printer.

The researchers were also able to form patterns using UV radation. The parts of the silk surface exposed to UV become less permeable to water or methanol and remain wrinkled when treated with vapor, while the parts not exposed to UV absorb the vapor and flatten out. This creates a new printed pattern that reflects the pattern of UV light exposed to the silk surface.

Once the material forms patterns, they can be erased and the textured silk can be regenerated with a cycle of heating the cooling. In tests, the researchers showed they could use the same material to print patterns over at least 50 cycles without any degradation in effect. 

Moreover, the researchers demonstrated how they can connect the silk/PDMS layer to a small electrical heating element to switch the silk “on” and “off” between wrinkled and wrinkle-free states.

In their study, the Tufts team said they hope there will even be applications beyond the information encoding, optical modulation, and thermal regulation cases they’ve outlined.

“Because of [silk fibroin’s] versatility, and ease of manufacture, I think there may be many future applications that we and others will come up with that we have not even imagined yet,” said Tufts engineering professor, and corresponding author, Fiorenzo Omenetto, in a press statement.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

indycar-aeroscreen-targets-improved-driver-safety

The challenge is to protect drivers without obstructing their vision.

IndyCar driver Scott Dixon testing the Aeroscreen. (Image source: IndyCar)

Open-cockpit racing preserves the gladiatorial feel of car racing in a way that closed-roof racing can’t capture. Even behind full-face helmets with reflective visors closed, fans can see the drivers at work behind the wheel, which helps draw a connection between the spectators and the athletes.

But open cockpits present risks to drivers, who can be struck in the head by debris when other drivers ahead have problems. Even worse, drivers can strike their heads on solid objects when they crash.

Some crashes will probably always be unsurvivable when the cars are going 220 mph or faster. But too many lesser incidents have seen drivers injured or killed. So racing engineers have pursued a solution to protect drivers.

new-water-based-invisible-ink-makes-your-secrets-eco-friendly
invisible ink, environmentally friendly, Institute of Advanced Materials at Nanjing University, rewriteable paper coating, water-jet printer
Researchers in China have developed a water-based invisible ink that can be used to encrypt secret or sensitive information that’s printed on paper. The method is a low-cost and environmentally friendly alternative to fluorescent inks currently used for this purpose today, researchers said. (Image source: Nanjing University of Posts and Telecommunications)

Researchers from the Institute of Advanced Materials at the Nanjing University of Posts and Telecommunications in China have developed a simple and secure printing technology in the form of a water-based invisible ink that can be used to encrypt secret or sensitive information.

The rather low-tech method is basically a rewriteable paper coating that can be printed by a water-jet printer on a manganese-complex-coated paper.

The writing produced by the technique is invisible to the naked eye. However, a 254-nanometer UV light shined on the paper reveals the message. Moreover, the paper can be recycled and reused for up to another 30 rounds of printing after heating the paper with a blow dryer for 15 to 30 seconds, which erases the message. 

The paper encryption method is not just low-tech, but also a low-cost and environmentally-friendly alternative to the current use of fluorescent security inks for protecting paper-based information, said Qiang Zhao, one of the researchers on the project and an associate professor of applied physics and computational mathematics at the institute.

“The rewritable feature significantly reduces the cost,” Zhao said in a press statement. Indeed, the cost per print is estimated to be RMB0.014 in Chinese yuan, or $0.002 US, he said.

“Most fluorescent security inks on the market used to record confidential information are environmentally unfriendly and cannot be erased,” Zhao added. “The paper is only a disposable recording medium.”

Zhao’s team developed the new method based on previous work researchers had done to regulate organic materials’ photoluminescence properties by modifying the molecular structure, he said. The team recently discovered that the material could change its optical or electrical properties through external stimulus alone.

“We developed a rewritable security printing method by utilizing the photoluminescence responses of manganese complex to water,” he said in the press statement.


Enhancing Safety and Security

Researchers view their water-jet printing method as a cost-efficient way to encrypt printed materials. But they said it does have one drawback – the short-wavelength UV light used to trigger the water-jet security printing can be harmful to humans.

Because of this, Zhao said the team is focused on developing humidity-sensitive manganese complexes that can be excited by visible or near-infrared light, which is much safer for humans.

“Our work is to provide a practical printing method,” Zhao said in the press statement. “Thus, we need to make sure that it’s non-toxic or has low harm to the human body.”

The team also is developing a high-level security printing to complement the low-tech, water-jet technique to protect information from general decryption methods, researchers said.

In this technique, researchers coat the paper with phosphine ligands, which can grab on to manganese in the manganese-halide salt solution ink to create manganese complex, they said.

This renders the recorded information invisible under both ambient light and UV light; however, a photoluminescence lifetime imaging (PLIM) technique can reveal the encrypted data in different colors of red, yellow, green, and blue, depending on the emission lifetime, Zhao said.

“The dynamic manipulation of the emission lifetime has been achieved for the first time by utilizing the reversible ionic interactions of manganese complexes,” he said in the release.

The team envisions that their techniques can be used widely in both the public and private sector to protect the security of information, especially in the economic and military fields, Zhao added.

Researchers published a paper of their work in the journal Matter

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

new-form-of-printing-produces-curvy-electronics

Researchers already have come up with numerous ways to make electronics more flexible. But until recently, creating electronics with a specific three-dimensional (3D) curve has remained an elusive endeavor.

Scientists at the University of Houston (UH) and the University of Colorado Boulder have collaborated to change this scenario with the development of a new printing process that they said can produce 3D curvy electronics on various scales.

Curvy Electronics, University of Houston, University of Colorado Boulder, conformal additive stamp printing
A team of researchers led by University of Houston engineer Cunjiang Yu has reported a new way to manufacture curvy, three-dimensional electronics. (Image source: University of Houston)

The breakthrough paves the way for contact lenses with integrated sensors and electronics to monitor health and improved vision as well as other types of next-generation wearables, optoelectronics, telecommunications, and biomedical applications, researchers said.

The new manufacturing method is conformal additive stamp printing, or CAS printing, which researchers invented when they couldn’t find a way to adapt existing printing techniques to their ultimate goal, said Cunjiang Yu, Bill D. Cook Associate Professor of Mechanical Engineering at UH.

“We tested a number of existing techniques to see if they were appropriate for manufacturing curvy electronics,” Yu, also a principal investigator with the Texas Center for Superconductivity at UH, said in a press statement. “The answer is no. They all had limitations and problems.”

Creating the Curve

Indeed, existing manufacturing technologies—such as microfabrication, don’t work for curved electronics because they are inherently designed to produce two-dimensional, flat electronic devices, Yu said.

However, next-generation demands for devices such as smart contact lenses, curved imagers, electronic antennas, and hemispherical solar cells will require fabrication techniques for curvier shapes ranging in size from millimeters to centimeters with a high degree of accuracy, he said.

“Electronic devices are typically manufactured in planar layouts, but many emerging applications, from optoelectronics to wearables, require three-dimensional curvy structures,” researchers wrote in an abstract for a paper on their work published in the journal Nature Electronics. “However, the fabrication of such structures has proved challenging due, in particular, to the lack of an effective manufacturing technology.”

CAS printing is a rather simple but effective technique for this purpose, according to researchers. It works like this: Researchers inflate an elastomeric balloon and then coat it with a sticky substance to use it as a stamping medium. They then use this object to apply pressure to a pre-fabricated electronic devices to pick up the electronics and then print them onto various curvy surfaces, they said.

In their work, researchers used a manual version of a CAS printer to create a variety of curvy devices, including silicon pellets, photodetector arrays, small antennas, hemispherical solar cells, and smart contact lenses, they said. They also designed an automated version of the printer that should facilitate scaling up production, researchers said.

Another paper featuring the team’s research also is published in the journal Nature.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

electronic-skin-can-'feel'-pain-for-robots,-prosthetics

Researchers have developed an electronic skin (e-skin) that can detect sensations similar to the ones human feel when they are experiencing pain, paving the way for more life-like prosthetic devices and humanoid robots.

Electronic Skin, Robots, Prosthetics, Daegu Gyeongbuk Institute of Science and Technology, South Korea, DGIST

Professor Jae Eun Jang (left) in the Department of Information and Communication Engineering at Daegu Gyeongbuk Institute of Science and Technology (GIST) and Combined M.S.-Ph.D. program student Minkyung Shim (right). The two were part of a team that developed a new e-skin that can detect pain and temperature. (Image source: DGIST)

A team from the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in South Korea developed the technology, which can detect “prick” and “hot” pain sensations similarly to how humans do, said Minkyug Shim, one of the institute researchers on the project.

While other research to develop e-skin for robotics and prosthetics has generally been focused on “enhancing performance such as the sensitivity, detecting range, and stability,” Shim said, the DGIST team took a different approach.

“We thought that pain feeling is very important to avoid the destruction by dangerous situation or materials,” he told Design News.

While enabling this type of detection in e-skins is a “complicated” problem to solve, Shim said, the team achieved its goal using a design based on zinc oxide nanowire technology.

Researchers applied the nanowire as a self-power tactile sensor that uses the piezoelectric effect, to generate electrical signals by detecting pressure, he said. At the same time, the team applied a temperature sensor using the nanowire so one sensor, in effect, performs the job of two, Shim said.

“Pressure and temperature were detected by single sensor structure, because these were carried out by only the zinc nanowire,” he told us.

One Nanowire, Two Tasks

To develop the e-skin, the team arranged electrodes on a polyimide flexible substrate and grew the nanowire, measuring the piezoelectric effect by pressure and the Seebeck effect by temperature change at the same time, researchers said. They also developed a signal processing technique that gauges the generation of pain signals considering the pressure level, stimulated area, and temperature, Shim said.

“If our system recognized the factor related to pain feeling by high pressure or temperature, the system generates the artificial pain signal (electrical),” he told Design News.

Researchers published a paper on their work in the Journal of Soft Robotics.

In the development of robots and prosthetics, the ability to sense pain using the e-skin the team developed can add a human-like sensation to a machine or artificial appendage, causing different reactions to stimuli, Shim said.

“The robot detecting the artificial pain signal can avoid a dangerous situation,” he told Design News. “In the case of prosthetics, the disabled people can feel real pain sensation if the technology transferring the generated pain signal by artificial prosthetic to the human central nervous system is developed.” 

Shim also presented a futuristic scenario in which artificial intelligence (AI) systems learn the feeling of pain so they can sympathize with humans, avoiding any potentially dangerous scenarios or even an attack by a potentially killer robot, he said.

“Many people are worrying about attack of developed AI robots,” Shim told Design News. “The solution is that the AI robots can sympathize with the pain of human by [using] our tactile system. If the AI robots learn the pain feeling by an external situation or attack and know that the situation is dangerous, the attack of AI robots on the human can be prevented in advance.”

Researchers aim to continue their work to add different sensations to the e-skin, such as the ability to sense when an object or material has a rough surface or texture, Shim said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

'smart-skin'-changes-color-in-the-sun,-inspired-by-chameleons

Researchers have found inspiration in the way a chameleon changes its skin color to develop a new, flexible smart skin that also can change its color in response to the environment without changing its size.

A team from Emory University developed the new material—comprised of two different hydrogels, one that provides coloration and the other provides the mechanical robustness and maintains constant volume, Khalid Salaita, an Emory professor of chemistry, told Design News.

Smart skin, Changes Color in the Sun, Chameleons, hydrogels, Emory University
A leaf-shape sample of the smart skin in the lab, in the midst of turning from yellow to green. (Image source: Corey Broman-Fulks, Emory University)

“Our approach employs smart skins that are colored using photonic crystals–which are made of tiny nanoscale particles that are crammed together at a set spacing and this spacing tunes the material’s color,” he told us. “The further the spacing, the more red the color and the more close the spacing, the more blue the color.”

Indeed, the change in coloration in chameleons and other organisms is not based on pigments, but on these photonic crystals, researchers said. Although the particles themselves are colorless, what causes the material to interfere with wavelengths of light is their periodicity.

The precise spacing between them allows certain light waves to pass through them while rejecting others, researchers said. The visible colors produced change depending on factors such as lighting conditions or shifts in the distance between the particles.

Solving the Problem

Researchers have been working for some time to control the photonic crystals that chameleons use to change skin color, but have run into a key problem time and again, Salaita said. The issue has been to invent a smart skin that also can change color by altering photonic crystals without changing the volume of the material itself.

“The key to our work was learning how to integrate two types of materials to optimize responsive color change and mechanical robustness,” Salaita told Design News. “We employed modeling to guide the experimental design and by screening different polymers we arrived at the responsive smart skin material.”

Despite their computational methods and ultimate success, the work was not without challenges, particularly in material choice, he told us.

“The main challenge was to identify hydrogels that had the ‘right’ mechanical properties such that they rapidly changed color in response to sunlight or thermal heating, while also maintaining mechanical robustness,” Salaita told Design News. “While we were guided by computational modeling, the work required screening hundreds of polymers with different crosslinker concentrations.”

In the end, the skin developed by Salaita’s team reacts to heat and sunlight while maintaining a near constant volume, he said. The team achieved this through the balance of the two materials–one that contains the responsive hydrogel photonic crystal while the second is mechanically robust and can be stretched or collapsed to maintain the constant volume, he told Design News.

Only after  studying video of chameleon skin cells and observing their formation did researchers find the right material combination and structure, Salaita said.

“We … found that the colored photonic crystal-containing cells were surrounded by non-colored cells,” he told Design News. “These non-colored cells acted like a spring, as the photonic crystals swelled or contracted the non-colored cells filled in the void and helped maintain a constant size of the skin.  So the inspiring aspect of the chameleon skin is that it maintains a constant size while changing color.”

Researchers published a paper on their work in the journal ACS Nano.

The team envisions myriad uses for the material it designed, including applications in chemical sensing, camouflage, and anti-counterfeiting, Salaita said.

“Over the past decades, responsive hydrogels have been engineered to respond to a wide range of triggers–small molecules, etc.–and we anticipate that we can integrate these past designs into our photonic crystal films,” he told Design News.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.