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Aeva Unveils Lidar on a Chip

There are scores of lidar startups. Why read about another one? 

It wouldn’t be enough to have the backing of a big car company, though Aeva has that. In April the company announced a partnership with Audi, and today it’s doing so with Porsche—the two upscale realms of the Volkswagen auto empire. 

Nor is it enough to claim that truly driverless cars are just around the bend. We’ve seen that promise made and broken many times. 

What makes this two-year-old company worth a look-see is its technology, which is unusual both for its miniaturization and for the way in which it modulates its laser beam. 

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3D Printing Industry

Formnext 2019 3D printing news you might have missed

Formnext 2019 may have been and gone, but there is still news to catch up on. Here is a digest of 3D printing updates from the largest additive manufacturing conference. Reporting live from the show, backed by a team covering all of the latest press releases from the event, 3D Printing Industry provided leading coverage from […]

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ScienceDaily

Wearable sweat sensor detects gout-causing compounds

There are numerous things to dislike about going to the doctor: Paying a copay, sitting in the waiting room, out-of-date magazines, sick people coughing without covering their mouths. For many, though, the worst thing about a doctor’s visit is getting stuck with a needle. Blood tests are a tried-and-true way of evaluating what is going on with your body, but the discomfort is unavoidable. Or maybe not, say Caltech scientists.

In a new paper published in Nature Biotechnology, researchers led by Wei Gao, assistant professor of medical engineering, describe a mass-producible wearable sensor that can monitor levels of metabolites and nutrients in a person’s blood by analyzing their sweat. Previously developed sweat sensors mostly target compounds that appear in high concentrations, such as electrolytes, glucose, and lactate. Gao’s sweat sensor is more sensitive than current devices and can detect sweat compounds of much lower concentrations, in addition to being easier to manufacture, the researchers say.

The development of such sensors would allow doctors to continuously monitor the condition of patients with illnesses like cardiovascular disease, diabetes, or kidney disease, all of which result in abnormal levels of nutrients or metabolites in the bloodstream. Patients would benefit from having their physician better informed of their condition, while also avoiding invasive and painful encounters with hypodermic needles.

“Such wearable sweat sensors have the potential to rapidly, continuously, and noninvasively capture changes in health at molecular levels,” Gao says. “They could enable personalized monitoring, early diagnosis, and timely intervention.”

Gao’s work is focused on developing devices based on microfluidics, a name for technologies that manipulate tiny amounts of liquids, usually through channels less than a quarter of a millimeter in width. Microfluidics are ideal for an application of this sort because they minimize the influence of sweat evaporation and skin contamination on the sensing accuracy. As freshly supplied sweat flows through the microchannels, the device can make more accurate measurements of sweat and can capture temporal changes in concentrations.

Until now, Gao and his colleagues say, microfluidic-based wearable sensors were mostly fabricated with a lithography-evaporation process, which requires complicated and expensive fabrication processes. His team instead opted to make their biosensors out of graphene, a sheet-like form of carbon. Both the graphene-based sensors and the tiny microfluidics channels are created by engraving the plastic sheets with a carbon dioxide laser, a device that is now so common that it is available to home hobbyists.

The research team opted to have their sensor measure respiratory rate, heart rate, and levels of uric acid and tyrosine. Tyrosine was chosen because it can be an indicator of metabolic disorders, liver disease, eating disorders, and neuropsychiatric conditions. Uric acid was chosen because, at elevated levels, it is associated with gout, a painful joint condition that is on the rise globally. Gout occurs when high levels of uric acid in the body begin crystallizing in the joints, particularly those of the feet, causing irritation and inflammation.

To see how well the sensors performed, the researchers ran a series of tests with healthy individuals and patients. To check sweat tyrosine levels, which are influenced by a person’s physical fitness, they used two groups of people: trained athletes and individuals of average fitness. As expected, the sensors showed lower levels of tyrosine in the sweat of the athletes. To check uric acid levels, they took a group of healthy individuals and monitored their sweat while they were fasting as well as after they ate a meal rich in purines, compounds in food that are metabolized into uric acid. The sensor showed uric acid levels rising after the meal. Gao’s team also performed a similar test with gout patients. Their uric acid levels, the sensor showed, were much higher than those of healthy people.

To check the accuracy of the sensors, the researchers also drew blood samples from the gout patients and healthy subjects. The sensors’ measurements of uric acid levels strongly correlated with levels of the compound in the blood.

Gao says the high sensitivity of the sensors, along with the ease with which they can be manufactured, means they could eventually be used by patients at home to monitor conditions like gout, diabetes, and cardiovascular diseases. Having accurate real-time information about their health could even allow a patient to adjust their own medication levels and diet as required.

“Considering that abnormal circulating nutrients and metabolites are related to a number of health conditions, the information collected from such wearable sensors will be invaluable for both research and medical treatment,” Gao says.

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Caltech and JPL Firing Quadrotors Out of Cannons

As useful as drones are up in the air, the process of getting them there tends to be annoying at best and dangerous at worst. Consider what it takes to launch something as simple as a DJI Mavic or a Parrot Anafi— you need to find a flat spot free of debris or obstructions, unfold the thing and let it boot up and calibrate and whatnot, stand somewhere safe(ish), and then get it airborne and high enough quick enough to avoid hitting any people or things that you care about.

I’m obviously being a little bit dramatic here, but ground launching drones is certainly both time consuming and risky, and there are occasions where getting a drone into the air as quickly and as safely as possible is a priority. At IROS in Macau earlier this month, researchers from Caltech and NASA’s Jet Propulsion Laboratory (JPL) presented a prototype for a ballistically launched drone—a football-shaped foldable quadrotor that gets fired out of a cannon, unfolds itself, and then flies off.

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ScienceDaily

Foam offers way to manipulate light

There is more to foam than meets the eye. Literally. A study by Princeton scientists has shown that a type of foam long studied by scientists is able to block particular wavelengths of light, a coveted property for next-generation information technology that uses light instead of electricity.

The researchers, integrating expertise from materials science, chemistry and physics, conducted exhaustive computational simulations of a structure known as a Weaire-Phelan foam. They found that this foam would allow some frequencies of light to pass through while completely reflecting others. This selective blocking, known as a photonic band gap, is similar to the behavior of a semiconductor, the bedrock material behind all modern electronics because of its ability to control the flow of electrons at extremely small scales.

“This has the property we want: an omnidirectional mirror for a certain range of frequencies,” said Salvatore Torquato, professor of chemistry and the Princeton Institute for the Science and Technology of Materials. Torquato, the Lewis Bernard Professor of Natural Sciences, published the results Nov. 6 in the Proceedings of the National Academy of Sciences, with coauthors Michael Klatt, a postdoctoral researcher, and physicist Paul Steinhardt, who is Princeton’s Albert Einstein Professor in Science.

While numerous examples of photonic band gaps have been shown previously in various types of crystals, the researchers believe that their new finding is the first example in a foam, similar to the froth of soap bubbles or a draft beer. Unlike the disordered foam of beer however, the Weaire-Phelan foam is a precisely structured arrangement with deep roots in mathematics and physics.

The origins of the Weaire-Phelan foam date to 1887 when the Scottish physicist Lord Kelvin proposed a structure for the “ether,” the mysterious substance that was then thought to comprise a background structure to all space. Although the concept of the ether was already falling out of favor at the time, Kelvin’s proposed foam went on to intrigue mathematicians for a century because it appeared to be the most efficient way to fill space with interlocking geometrical shapes that have the least possible surface area.

In 1993, physicists Denis Weaire and Robert Phelan found an alternative arrangement that requires slightly less surface area. Since then, interest in the Weaire-Phelan structure was mainly in the mathematics, physics and artistic communities. The structure was used as the outer wall of the “Beijing Water Cube” created for the 2008 Olympics. The new finding now makes the structure of interest to materials scientists and technologists.

“You start out with a classical, beautiful problem in geometry, in mathematics, and now suddenly you have this material that opens up a photonic band gap,” Torquato said.

Torquato, Klatt and Steinhardt became interested in the Weaire-Phelan foam as a tangent of another project in which they were investigating “hyperuniform” disordered materials as an innovative way to control light. Although not their original focus, the three realized that this precisely structured foam had intriguing properties.

“Little by little, it became apparent that there was something interesting here,” Torquato said. “And eventually we said, ‘Ok, let’s put the main project to the side for a while to pursue this.'”

“Always look out for what’s at the wayside of research,” Klatt added.

Weaire, who was not involved in this new finding, said that the Princeton discovery is part of a broadening interest in the material since he and Phelan discovered it. He said the possible new use in optics likely stems from the material being very isotropic, or not having strongly directional properties.

“The fact that it displays a photonic band gap is very interesting because it turns out to have so many special properties,” said Andrew Kraynik, an expert in foams who earned his Ph.D. in chemical engineering from Princeton in 1977 and has studied the Weaire-Phelan foam extensively but was not involved in the Princeton study. Another Princeton connection, said Kraynik, is that a key tool in discovering and analyzing the Weaire-Phelan foam is a software tool called Surface Evolver, which optimizes shapes according to their surface properties and was written by Ken Brakke, who earned his Ph.D. in math at Princeton in 1975.

To show that the Weaire-Phelan foam exhibited the light-controlling properties they were seeking, Klatt developed a meticulous set of calculations that he executed on the supercomputing facilities of the Princeton Institute for Computational Science and Engineering.

“The programs he had to run are really computationally intensive,” Torquato said.

The work opens numerous possibilities for further invention, said the researchers, who dubbed the new area of work as “phoamtonics” (a mashup of “foam” and “photonics”). Because foams occur naturally and are relatively easy to make, one possible goal would be to coax raw materials to self-organize into the precise arrangement of the Weaire-Phelan foam, Torquato said.

With further development, the foam could transport and manipulate light used in telecommunications. Currently much of the data traversing the internet is carried by glass fibers. However, at its destination, the light is converted back to electricity. Photonic band gap materials could guide the light much more precisely than conventional fiber optic cables and might serve as optical transistors that perform computations using light.

“Who knows?” said Torquato. “Once you have this as a result, then it provides experimental challenges for the future.”

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Go with the flow: Scientists design new grid batteries for renewable energy

How do you store renewable energy so it’s there when you need it, even when the sun isn’t shining or the wind isn’t blowing? Giant batteries designed for the electrical grid — called flow batteries, which store electricity in tanks of liquid electrolyte — could be the answer, but so far utilities have yet to find a cost-effective battery that can reliably power thousands of homes throughout a lifecycle of 10 to 20 years.

Now, a battery membrane technology developed by researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) may point to a solution.

As reported in the journal of Joule, the researchers developed a versatile yet affordable battery membrane — from a class of polymers known as AquaPIMs. This class of polymers makes long-lasting and low-cost grid batteries possible based solely on readily available materials such as zinc, iron, and water. The team also developed a simple model showing how different battery membranes impact the lifetime of the battery, which is expected to accelerate early stage R&D for flow-battery technologies, particularly in the search for a suitable membrane for different battery chemistries.

“Our AquaPIM membrane technology is well-positioned to accelerate the path to market for flow batteries that use scalable, low-cost, water-based chemistries,” said Brett Helms, a principal investigator in the Joint Center for Energy Storage Research (JCESR) and staff scientist at Berkeley Lab’s Molecular Foundry who led the study. “By using our technology and accompanying empirical models for battery performance and lifetime, other researchers will be able to quickly evaluate the readiness of each component that goes into the battery, from the membrane to the charge-storing materials. This should save time and resources for researchers and product developers alike.”

Most grid battery chemistries have highly alkaline (or basic) electrodes — a positively charged cathode on one side, and a negatively charged anode on the other side. But current state-of-the-art membranes are designed for acidic chemistries, such as the fluorinated membranes found in fuel cells, but not for alkaline flow batteries. (In chemistry, pH is a measure of the hydrogen ion concentration of a solution. Pure water has a pH of 7 and is considered neutral. Acidic solutions have a high concentration of hydrogen ions, and are described as having a low pH, or a pH below 7. On the other hand, alkaline solutions have low concentrations of hydrogen ions and therefore have a high pH, or a pH above 7. In alkaline batteries, the pH can be as high as 14 or 15.)

Fluorinated polymer membranes are also expensive. According to Helms, they can make up 15% to 20% of the battery’s cost, which can run in the range of $300/kWh.

One way to drive down the cost of flow batteries is to eliminate the fluorinated polymer membranes altogether and come up with a high-performing yet cheaper alternative such as AquaPIMs, said Miranda Baran, a graduate student researcher in Helms’ research group and the study’s lead author. Baran is also a Ph.D. student in the Department of Chemistry at UC Berkeley.

Getting back to basics

Helms and co-authors discovered the AquaPIM technology — which stands for “aqueous-compatible polymers of intrinsic microporosity” — while developing polymer membranes for aqueous alkaline (or basic) systems as part of a collaboration with co-author Yet-Ming Chiang, a principal investigator in JCESR and Kyocera Professor of Materials Science and Engineering at the Massachusetts Institute of Technology (MIT).

Through these early experiments, the researchers learned that membranes modified with an exotic chemical called an “amidoxime” allowed ions to quickly travel between the anode and cathode.

Later, while evaluating AquaPIM membrane performance and compatibility with different grid battery chemistries — for example, one experimental setup used zinc as the anode and an iron-based compound as the cathode — the researchers discovered that AquaPIM membranes lead to remarkably stable alkaline cells.

In addition, they found that the AquaPIM prototypes retained the integrity of the charge-storing materials in the cathode as well as in the anode. When the researchers characterized the membranes at Berkeley Lab’s Advanced Light Source (ALS), the researchers found that these characteristics were universal across AquaPIM variants.

Baran and her collaborators then tested how an AquaPIM membrane would perform with an aqueous alkaline electrolyte. In this experiment, they discovered that under alkaline conditions, polymer-bound amidoximes are stable — a surprising result considering that organic materials are not typically stable at high pH.

Such stability prevented the AquaPIM membrane pores from collapsing, thus allowing them to stay conductive without any loss in performance over time, whereas the pores of a commercial fluoro-polymer membrane collapsed as expected, to the detriment of its ion transport properties, Helms explained.

This behavior was further corroborated with theoretical studies by Artem Baskin, a postdoctoral researcher working with David Prendergast, who is the acting director of Berkeley Lab’s Molecular Foundry and a principal investigator in JCESR along with Chiang and Helms.

Baskin simulated structures of AquaPIM membranes using computational resources at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC) and found that the structure of the polymers making up the membrane were significantly resistant to pore collapse under highly basic conditions in alkaline electrolytes.

A screen test for better batteries

While evaluating AquaPIM membrane performance and compatibility with different grid battery chemistries, the researchers developed a model that tied the performance of the battery to the performance of various membranes. This model could predict the lifetime and efficiency of a flow battery without having to build an entire device. They also showed that similar models could be applied to other battery chemistries and their membranes.

“Typically, you’d have to wait weeks if not months to figure out how long a battery will last after assembling the entire cell. By using a simple and quick membrane screen, you could cut that down to a few hours or days,” Helms said.

The researchers next plan to apply AquaPIM membranes across a broader scope of aqueous flow battery chemistries, from metals and inorganics to organics and polymers. They also anticipate that these membranes are compatible with other aqueous alkaline zinc batteries, including batteries that use either oxygen, manganese oxide, or metal-organic frameworks as the cathode.

Researchers from Berkeley Lab, UC Berkeley, Massachusetts Institute of Technology, and Istituto Italiano di Tecnologia participated in the study.

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Education & Research Resources from Industry

There is a limited number of Keysight’s Education and Research Resources USB drives still available. Get over 200 technical items such as application notes, technical briefs, links to videos and webinars. Topics include materials research, test and measurement science, software and much more. Don’t miss out on this must-have educational tool that contains the latest educational resources to help you succeed in your classroom and lab.

Please note: This offer is only available in the United States and Canada.

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IEEE Spectrum

Drones as Detectives: Surveying Crime Scenes for Evidence

When detectives and other forensics specialists arrive at a crime scene, there is a pressing need to survey the area quickly. Environmental disturbances such as wind or an incoming tide could ruin valuable evidence, and even the investigators themselves are at risk of contaminating the crime scene. Could a fleet of evidence-surveying drones be of help?

Pompílio Araújo, a criminal expert for the Federal Police of Brazil, is responsible for recording crime scenes exactly as found. In his other role as a researcher at the Intelligent Vision Research Lab at Federal University of Bahia, he is trying to make his first job easier by developing drones that can—very quickly—home in on a piece of evidence and record it from multiple angles.

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New liquid crystals allowing directed transmission of electricity synthesized

Liquid and solid — most people are unaware that there can be states in between. Liquid crystals are representative of one such state. While the molecules in liquids swim around at random, neighboring molecules in liquid crystals are aligned as in regular crystal grids, but the material is still liquid. Liquid crystals are thus an example of an intermediate state that is neither really solid nor really liquid¬¬. They flow like a liquid, and yet their molecules are grouped in small, regularly ordered units. A particular application of liquid crystals is optical imaging technology as in the screens of televisions, smartphones, and calculators. All LCD — or liquid crystal display — devices use these molecules.

Researchers at the Institute of Organic Chemistry at Johannes Gutenberg University Mainz (JGU) have synthesized novel liquid crystals in a project sponsored by the German Research Foundation (DFG). “If you slowly cool our liquid crystalline materials, the molecules align in a self-assembly process to form columns,” explained Professor Heiner Detert of JGU. “We can imagine these columns like piles of beer mats stacked one on top of the other. But the special thing is that these columns conduct electrical energy along their whole length.” The materials can thus serve as organic, liquid crystalline “power cables” and provide targeted electricity transmission in electronic components. While most materials conduct positive charges carried by holes, the new molecules actually conduct electrons. An additional advantage of a liquid crystalline power cable is that if it ruptures, any such rupture will heal entirely by itself.

The researchers have identified a particularly interesting effect exhibited by their synthesized molecules: If a single molecule is stimulated by exposure to UV light, it will glow in response. If the concentration of the molecule increases, this effect disappears only to reappear again when the concentration continues to increase. If the molecules are suspended in a solvent or arranged on a film, they will fluoresce in various colors when irradiated with UV light.

Detert and his team together with Professor Matthias Lehmann of the Julius-Maximilians-Universität Würzburg recently published their results in Chemistry — A European Journal. Experts classified the research results as exceptionally significant and the journal editors selected the article as a Hot Paper. The lead author, Natalie Tober, is supported by a scholarship awarded by the Carl Zeiss Foundation.

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A new, natural wax coating that makes garments water-resistant and breathable

There is a growing concern over the environmental impact of textile production and many waterproof products on the market are prepared with toxic chemicals. This is increasing demand for new sustainable material alternatives, but making non-toxic, breathable and waterproof textiles, sustainably and economically has thus far proven to be a challenge.

Now Aalto researchers have developed an ecological and water repellent wax particle coating suitable for wood cellulose fibres, which also retains the breathability and natural feel of the textile. The coating uses carnauba wax, which is also used in such things as medicines, foodstuffs, as well as the surface treatment of fruits and car waxes. The new coating is suitable not only for textiles but also for other cellulose-based materials.

During the processing, the wax is thawed and decomposed in water into wax particles that are anionic (i.e. negatively charged) just like cellulose. For the wax particles to adhere well to the cellulose surface, something cationic (i.e. positively charged) is needed as a buffer, since the oppositely charged particles attract one another. In previous studies, a natural protein called polylysine was used for this.

However, as Aalto University PhD student Nina Forsman points out, ‘Polylysine is very expensive so in our current study, it’s been substituted with a much cheaper, cationic starch that’s already commercially available’. Though cationic starch is not quite as effective as polylysine, two layers of the starch mixed with two wax particles are sufficient to make the textile waterproof.

The researchers compared the breathability of textiles treated with natural wax with textiles that had been treated with commercial products. Ecological wax particles made the textiles waterproof and also retained their breathability, while textiles treated with commercial controls had reduced breathability.

The multidisciplinary research team also included designer Matilda Tuure from the Aalto University School of Arts, Design and Architecture and as part of her master’s thesis, she designed and manufactured three coats for which the wax coatings were put through their paces.

Waxing and dyeing at the same time The wax coating can be applied to the textile by dipping, spraying or brushing onto the surface of the textile, and all three methods were tested. They found that dipping is suitable for smaller items of clothing and spraying or brushing is better for larger ones. In industrial-scale production, wax treatment could be part of the textile finishing process along with the colour pigmentation of the wax, which makes dyeing and waterproofing possible at the same time.

The research team found that the wax coating is not resistant to detergent washing, so the product is best suited for less frequently washed outer garments such as jackets. For the sake of simplicity of use, the consumer could potentially apply the coating themselves to the textile after each wash, and this requires more research and development though.

The effect of the drying temperature after wax treatment on waterproofing was also observed, and it was concluded that the best water resistance is obtained when the drying temperature is lower than the melting temperature of the wax.

“We tested the coating on different textile materials: viscose, tencel, cotton, hemp and cotton knitwear. We found that the surface roughness of textiles affects how well it repels water — the rougher the surface, the better. This is because, on a rough surface, water droplets contact the textile surface in a smaller area, “says Forsman.

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