Molecules that are made up of multiple repeating subunits, known as monomers, which may vary or not in their chemical structure, are classified as macromolecules or polymers. Examples exist in nature, including proteins and nucleic acids, which are at the heart of all biological systems. Proteins not only form the basis of structural elements in cells, they also serve as enzymes — which catalyze essentially all of the myriad of chemical transformations that take place in living systems. In contrast, nucleic acids such as DNA and RNA serve as informational macromolecules. DNA stores the cell’s genetic information, which is selectively copied into RNA molecules that provide the blueprints for the synthesis of proteins. In addition, long chains comprised of sugar units provide energy reserves in the form of glycogen, which is stored in the liver and the muscles. These diverse classes of polymeric molecules all have one feature in common: They spontaneously fold into characteristic spatial conformations, for example the famous DNA double helix, which in most cases are essential for their biochemical functions.
Professor Ivan Huc (Department of Pharmacy, LMU) studies aspects of the self-organization processes that enable macromolecules to adopt defined folded shapes. The molecular structures found in nature provide him with models, whose properties he tries to reproduce in the laboratory with non-natural molecules that are neither proteins, nucleic acids or sugar-like. More specifically, he uses the tools of synthetic chemistry to elucidate the underlying principles of self-organization — by constructing molecules that are expressly designed to fold into predetermined shapes. Beginning with monomers that his group has developed, he sets out to produce what he calls ‘foldamers’, by assembling the monomers one by one to generate a folded macromolecule.
Structures with low degrees of symmetry
“The normal way to get the complex structure of proteins is to use different types of monomers, called amino acids,” as Huc reports. “And the normal method to connect different amino acids in the the correct order is to link them one by one.” The sequence of amino acids contains the folding information that allows different protein sequences to fold in different ways.
“But we discovered something unexpected and spectacular,” comments Huc. He and his colleagues in Munich, Groningen, Bordeaux and Berlin used organic, sulfur-containing monomers to spontaneously get cyclic macromolecules with a complex shape, as illustrated by their low degree of symmetry, without requiring a specific sequence. The macromolecules self-synthesize — no further conditions are necessary. “We only put one monomer type in a flask and wait,” Huc says. “This is typical for a polymerization reaction, but polymers from a single monomer usually don´t adopt complex shapes and don’t stop growing at a precise chain length.”
To further control the reaction, the scientists also used either a small guest molecule or a metal ion. The regulator binds within the growing macromolecule and causes monomers to arrange themselves around it. By choosing a regulator with the appropriate characteristics, the authors of the new study were able to produce structures with a predetermined number of subunits. The cyclic macromolecules exhibited low levels of symmetry. Some consisted of either 13, 17 or 23 subunits. Since 13, 17 and 23 are prime numbers, the corresponding folded shapes exhibit low degrees of symmetry.
A model for biological and industrial processes
Interest in the elucidation of such mechanisms is not restricted to the realm of basic research. Huc and his colleagues hope that their approach will lead to the fabrication of designer plastics. Conventional polymers usually consist of mixtures of molecules that vary in length (i.e. the number of monomers they contain). This heterogeneity has an impact on their physical properties. Hence, the ability to synthesize polymer chains of an exact length and/or geometry is expected to lead to materials with novel and interesting behaviors.
Furthermore, foldamers like those that have now been synthesized show close structural resemblances to biopolymers. They therefore offer an ideal model system in which to study the properties of proteins. Every protein is made up of a defined linear (i.e. unbranched) sequence of amino acids, which constitutes its ‘primary structure’. But most amino-acid chains fold into local substructures such as helically coiled stretches, or parallel strands that can form sheets. These units represent the protein’s secondary structure. The term ‘tertiary structure’ is applied to the fully folded single chain. This in turn can interact with other chains to form a functional unit or quaternary structure.
Huc’s ultimate goal is to mimic complex biological mechanisms using structurally defined, synthetic precursors. He wants to understand how, for example, enzymes fold into the correct, biologically active conformation following their synthesis in cells. Molecules whose properties can be precisely controlled in the laboratory provide ideal models with which to work out the answers and perhaps to go beyond enzymes themselves.
UK-based researchers looked at use of 3D printing to manufacture low cost Multiple Input Multiple Output (MIMO) antennas for 5G communication systems. These proposed MIMOs, fabricated using 3D printing, are capable of delivering beams in multiple directions, providing continuous, real-time coverage without the use of phase shifters. Additionally, they can operate at the 28 GHz […]
Researchers have designed a new camera that could allow hypertelescopes to image multiple stars at once. The enhanced telescope design holds the potential to obtain extremely high-resolution images of objects outside our solar system, such as planets, pulsars, globular clusters and distant galaxies.
“A multi-field hypertelescope could, in principle, capture a highly detailed image of a star, possibly also showing its planets and even the details of the planets’ surfaces,” said Antoine Labeyrie, emeritus professor at the Collège de France and Observatoire de la Cote d’Azur, who pioneered the hypertelescope design. “It could allow planets outside of our solar system to be seen with enough detail that spectroscopy could be used to search for evidence of photosynthetic life.”
In The Optical Society’s (OSA) journal Optics Letters, Labeyrie and a multi-institutional group of researchers report optical modeling results that verify that their multi-field design can substantially extend the narrow field-of-view coverage of hypertelescopes developed to date.
Making the mirror larger
Large optical telescopes use a concave mirror to focus light from celestial sources. Although larger mirrors can produce more detailed pictures because of their reduced diffractive spreading of the light beam, there is a limit to how large these mirrors can be made. Hypertelescopes are designed to overcome this size limitation by using large arrays of mirrors, which can be spaced widely apart.
Researchers have previously experimented with relatively small prototype hypertelescope designs, and a full-size version is currently under construction in the French Alps. In the new work, researchers used computer models to create a design that would give hypertelescopes a much larger field of view. This design could be implemented on Earth, in a crater of the moon or even on an extremely large scale in space.
Building a hypertelescope in space, for example, would require a large flotilla of small mirrors spaced out to form a very large concave mirror. The large mirror focuses light from a star or other celestial object onto a separate spaceship carrying a camera and other necessary optical components.
“The multi-field design is a rather modest addition to the optical system of a hypertelescope, but should greatly enhance its capabilities,” said Labeyrie. “A final version deployed in space could have a diameter tens of times larger than the Earth and could be used to reveal details of extremely small objects such as the Crab pulsar, a neutron star believed to be only 20 kilometers in size.”
Expanding the view
Hypertelescopes use what is known as pupil densification to concentrate light collection to form high-resolution images. This process, however, greatly limits the field of view for hypertelescopes, preventing the formation of images of diffuse or large objects such as a globular star cluster, exoplanetary system or galaxy.
The researchers developed a micro-optical system that can be used with the focal camera of the hypertelescope to simultaneously generate separate images of each field of interest. For star clusters, this makes it possible to obtain separate images of each of thousands of stars simultaneously.
The proposed multi-field design can be thought of as an instrument made of multiple independent hypertelescopes, each with a differently tilted optical axis that gives it a unique imaging field. These independent telescopes focus adjacent images onto a single camera sensor.
The researchers used optical simulation software to model different implementations of a multi-field hypertelescope. These all provided accurate results that confirmed the feasibility of multi-field observations.
Incorporating the multi-field addition into hypertelescope prototypes would require developing new components, including adaptive optics components to correct residual optical imperfections in the off-axis design. The researchers are also continuing to develop alignment techniques and control software so that the new camera can be used with the prototype in the Alps. They have also developed a similar design for a moon-based version.
A modern airplane’s fuselage is made from multiple sheets of different composite materials, like so many layers in a phyllo-dough pastry. Once these layers are stacked and molded into the shape of a fuselage, the structures are wheeled into warehouse-sized ovens and autoclaves, where the layers fuse together to form a resilient, aerodynamic shell.
Now MIT engineers have developed a method to produce aerospace-grade composites without the enormous ovens and pressure vessels. The technique may help to speed up the manufacturing of airplanes and other large, high-performance composite structures, such as blades for wind turbines.
The researchers detail their new method in a paper published today in the journal Advanced Materials Interfaces.
“If you’re making a primary structure like a fuselage or wing, you need to build a pressure vessel, or autoclave, the size of a two- or three-story building, which itself requires time and money to pressurize,” says Brian Wardle, professor of aeronautics and astronautics at MIT. “These things are massive pieces of infrastructure. Now we can make primary structure materials without autoclave pressure, so we can get rid of all that infrastructure.”
Wardle’s co-authors on the paper are lead author and MIT postdoc Jeonyoo Lee, and Seth Kessler of Metis Design Corporation, an aerospace structural health monitoring company based in Boston.
Out of the oven, into a blanket
In 2015, Lee led the team, along with another member of Wardle’s lab, in creating a method to make aerospace-grade composites without requiring an oven to fuse the materials together. Instead of placing layers of material inside an oven to cure, the researchers essentially wrapped them in an ultrathin film of carbon nanotubes (CNTs). When they applied an electric current to the film, the CNTs, like a nanoscale electric blanket, quickly generated heat, causing the materials within to cure and fuse together.
With this out-of-oven, or OoO, technique, the team was able to produce composites as strong as the materials made in conventional airplane manufacturing ovens, using only 1 percent of the energy.
The researchers next looked for ways to make high-performance composites without the use of large, high-pressure autoclaves — building-sized vessels that generate high enough pressures to press materials together, squeezing out any voids, or air pockets, at their interface.
“There’s microscopic surface roughness on each ply of a material, and when you put two plys together, air gets trapped between the rough areas, which is the primary source of voids and weakness in a composite,” Wardle says. “An autoclave can push those voids to the edges and get rid of them.”
Researchers including Wardle’s group have explored “out-of-autoclave,” or OoA, techniques to manufacture composites without using the huge machines. But most of these techniques have produced composites where nearly 1 percent of the material contains voids, which can compromise a material’s strength and lifetime. In comparison, aerospace-grade composites made in autoclaves are of such high quality that any voids they contain are neglible and not easily measured.
“The problem with these OoA approaches is also that the materials have been specially formulated, and none are qualified for primary structures such as wings and fuselages,” Wardle says. “They’re making some inroads in secondary structures, such as flaps and doors, but they still get voids.”
Part of Wardle’s work focuses on developing nanoporous networks — ultrathin films made from aligned, microscopic material such as carbon nanotubes, that can be engineered with exceptional properties, including color, strength, and electrical capacity. The researchers wondered whether these nanoporous films could be used in place of giant autoclaves to squeeze out voids between two material layers, as unlikely as that may seem.
A thin film of carbon nanotubes is somewhat like a dense forest of trees, and the spaces between the trees can function like thin nanoscale tubes, or capillaries. A capillary such as a straw can generate pressure based on its geometry and its surface energy, or the material’s ability to attract liquids or other materials.
The researchers proposed that if a thin film of carbon nanotubes were sandwiched between two materials, then, as the materials were heated and softened, the capillaries between the carbon nanotubes should have a surface energy and geometry such that they would draw the materials in toward each other, rather than leaving a void between them. Lee calculated that the capillary pressure should be larger than the pressure applied by the autoclaves.
The researchers tested their idea in the lab by growing films of vertically aligned carbon nanotubes using a technique they previously developed, then laying the films between layers of materials that are typically used in the autoclave-based manufacturing of primary aircraft structures. They wrapped the layers in a second film of carbon nanotubes, which they applied an electric current to to heat it up. They observed that as the materials heated and softened in response, they were pulled into the capillaries of the intermediate CNT film.
The resulting composite lacked voids, similar to aerospace-grade composites that are produced in an autoclave. The researchers subjected the composites to strength tests, attempting to push the layers apart, the idea being that voids, if present, would allow the layers to separate more easily.
“In these tests, we found that our out-of-autoclave composite was just as strong as the gold-standard autoclave process composite used for primary aerospace structures,” Wardle says.
The team will next look for ways to scale up the pressure-generating CNT film. In their experiments, they worked with samples measuring several centimeters wide — large enough to demonstrate that nanoporous networks can pressurize materials and prevent voids from forming. To make this process viable for manufacturing entire wings and fuselages, researchers will have to find ways to manufacture CNT and other nanoporous films at a much larger scale.
“There are ways to make really large blankets of this stuff, and there’s continuous production of sheets, yarns, and rolls of material that can be incorporated in the process,” Wardle says.
He plans also to explore different formulations of nanoporous films, engineering capillaries of varying surface energies and geometries, to be able to pressurize and bond other high-performance materials.
“Now we have this new material solution that can provide on-demand pressure where you need it,” Wardle says. “Beyond airplanes, most of the composite production in the world is composite pipes, for water, gas, oil, all the things that go in and out of our lives. This could make making all those things, without the oven and autoclave infrastructure.”
This research was supported, in part, by Airbus, ANSYS, Embraer, Lockheed Martin, Saab AB, Saertex, and Teijin Carbon America through MIT’s Nano-Engineered Composite aerospace Structures (NECST) Consortium.
Autonomous vehicles (AV) combine multiple sensors, computers and communication technology to make driving safer and improve the driver’s experience. Learn about design and test of complex sensor and communication technologies being built into AVs from our white paper and posters.
Key points covered in our AV resources:
Comparison of dedicated short-range communications and C-V2X technologies
Scientists have developed a deep-learning based motion-capture software that uses multiple camera views to model the movements of a fly in three dimensions. The ultimate aim is to use this knowledge to design fly-like robots.
“Just think about what a fly can do,” says Professor Pavan Ramdya, whose lab at EPFL’s Brain Mind Institute, with the lab of Professor Pascal Fua in EPFL’s Institute for Computer Science, led the study. “A fly can climb across terrain that a wheeled robot would not be able to.”
Flies aren’t exactly endearing to humans. We rightly associate them with less-than-appetizing experiences in our daily lives. But there is an unexpected path to redemption: Robots. It turns out that flies have some features and abilities that can inform a new design for robotic systems.
“Unlike most vertebrates, flies can climb nearly any terrain,” says Ramdya. “They can stick to walls and ceilings because they have adhesive pads and claws on the tips of their legs. This allows them to basically go anywhere. That’s interesting also because if you can rest on any surface, you can manage your energy expenditure by waiting for the right moment to act.”
It was this vision of extracting the principles that govern fly behavior to inform the design of robots that drove the development of DeepFly3D, a motion-capture system for the fly Drosophila melanogaster, a model organism that is nearly ubiquitously used across biology.
In Ramdya’s experimental setup, a fly walks on top of a tiny floating ball — like a miniature treadmill — while seven cameras record its every movement. The fly’s top side is glued onto an unmovable stage so that it always stays in place while walking on the ball. Nevertheless, the fly “believes” that it is moving freely.
The collected camera images are then processed by DeepFly3D, a deep-learning software developed by Semih Günel, a PhD student working with both Ramdya’s and Fua’s labs. “This is a fine example of where an interdisciplinary collaboration was necessary and transformative,” says Ramdya. “By leveraging computer science and neuroscience, we’ve tackled a long-standing challenge.”
What’s special about DeepFly3D is that is can infer the 3D pose of the fly — or even other animals — meaning that it can automatically predict and make behavioral measurements at unprecedented resolution for a variety of biological applications. The software doesn’t need to be calibrated manually and it uses camera images to automatically detect and correct any errors it makes in its calculations of the fly’s pose. Finally, it also uses active learning to improve its own performance.
DeepFly3D opens up a way to efficiently and accurately model the movements, poses, and joint angles of a fruit fly in three dimensions. This may inspire a standard way to automatically model 3D pose in other organisms as well.
“The fly, as a model organism, balances tractability and complexity very well,” says Ramdya. “If we learn how it does what it does, we can have important impact on robotics and medicine and, perhaps most importantly, we can gain these insights in a relatively short period of time.”
This regulation falls under what the FCC calls “Title 47 CFR Part 15” (15th subsection of the 47th section of the Code of Federal Regulations).
In Europe, there is a similar regulation called CISPR 22. The requirements are very similar, but somewhat stricter in regards to RF emissions at some frequencies. Other countries and regions have similar regulations on electromagnetic emissions.
For all intents and purposes, these regulations include almost all electronic products, since very few products are able to run at frequencies less than 9 kHz.
However, if your product is simple enough you may be able to bypass FCC certification by purposefully designing it to operate below 9 kHz.
For example, some microcontrollers can run at frequencies below 9 kHz. Even then you need to make sure that none of the harmonics exceed the standard limits.
All electronic products with oscillating signals will emit some amount of electromagnetic radiation (i.e. radio waves), generally referred to as EMI, or ElectroMagnetic Interference. Government regulators want to make sure that product emissions don’t interfere with wireless communication.
There are two classes of FCC testing: Class A and Class B. Class A is an easier test to pass, and is intended for products that will be used in industrial applications. Class B is for consumer products and requires stricter testing.
FCC certification can be further split into two types: intentional radiator and non-intentional radiator. The category is determined by whether your product incorporates wireless capabilities such as Bluetooth, Wi-Fi, cellular, or any other type of radio transmitter.
Regardless of the type or classification of your product, if it is AC powered it must also meet conducted emissions limits. This applies whether a product is directly powered from the mains, or whether it is DC powered from an AC adapter that is supplied from the mains.
In general, conducted emissions can be easily suppressed by the use of appropriate ferrite cores. This is the lump often seen close to the DC plugs of AC adapters.
The FCC classifies an intentional radiator as any product that intentionally transmits radio frequency (RF) waves (also called more broadly electromagnetic radiation). A cellular phone or an Internet of Things (IoT) device are examples of intentional radiators.
A non-intentional radiator is classified as a product that doesn’t intentionally emit radio frequency waves. Every electronic product will unintentionally emit some level of electromagnetic radiation.
Intentional radiator certification is more involved and more expensive than non-intentional certification.
One of the first things you should consider is at what frequency will your product operate? Depending on where your product will be sold, you may not be able to certify some devices that operate at certain frequencies.
For example, some wireless sensor networks operate at sub-GHz frequencies, most likely in the unlicensed Industrial Scientific and Medical (ISM) bands.
In Europe this band is 863MHz to 870MHz, usually referred to as the 868MHz band. In North America, this ISM band is 902 MHz to 928 MHz, usually known as the 915MHz band.
A sensor network operating in the 868 MHz band is not going to get certified in North America, regardless of the radiated power. The same applies to using a 915MHz device in Europe.
One of the best ways to reduce the certification costs for wireless functions in your product is to use pre-certified radio modules. These modules are verified to be within the limits of allowable RF power output levels.
Also, they won’t unintentionally radiate, thus preventing your product from radiating outside of the intended operating frequency band.
One important thing to note is that your choice of antenna can affect certifications. Antenna gain and radiation efficiency can cause the field strength of the radiation to exceed certification limits, even though the output power of the module itself may be within limits.
This is why you should consider using pre-certified modules, with a built-in antenna if possible, for any of your wireless functions. This will save you the extra cost for intentional radiator certification, since your wireless functions will be performed by the pre-certified modules. Doing this will save you thousands of dollars.
Electromagnetic emissions are measured using a specialized testing chamber called an anechoic chamber (“an-echoic” or non-echoing) which is a specialized room designed to absorb all electromagnetic radiation. The chamber is outfitted with sensors for detecting electromagnetic emissions.
The cost to rent a testing chamber is one of the primary costs of obtaining FCC certification. The rental cost for one of these chambers can be up to $1,000 per hour.
At a minimum, each testing session will take a couple of hours. Most products require several sessions in order to pass.
Most entrepreneurs choose to hire a third party certification testing company such as Intertek or SGS to perform all of the necessary FCC testing.
Typically, you will need to make some modifications to your electronics design in order to pass the emissions testing. This includes such things as adding ferrite beads, capacitors, shields, and other modifications to reduce emissions outside of the intended frequency.
While EMI is concerned with a product’s interference with other electronic devices, SAR is concerned with the absorption of electromagnetic energy by the human body.
SAR testing is mostly applied to smartphones, tablets and laptops that have high power radio transmitters, and is something to be aware of when designing such products.
UL certification is necessary in the United States and Canada if the product plugs directly into an AC outlet. Primarily the UL is concerned with the electrical safety of your product.
This certification ensures that your product doesn’t start an electrical fire, or cause other safety issues. There are many UL certifications, each tailored to the type of product and its intended use.
For example, one of the most common UL certifications is the UL60950 for information technology equipment. If you have a medical product, you will need UL60601 certification.
Also note that many UL certifications, such as UL60950, will require prior UL certifications that apply to sub-parts of the overall product.
For example, the PCB material in your product along with all the plastic enclosures, should meet the UL94 standard, typically UL94-V0. If your product contains li-ion batteries, these should comply with the UL1642 standard.
Europe generally has its own safety certifications but they are generally very similar to their equivalent UL standards. Usually, a product that is UL-approved needs to have a separate certification to be approved for Europe.
There is a move underway to harmonize these standards. One that is very prominent is IEC62638–1 or its equivalent UL62368. This harmonized standard will supersede UL60950 in North America in late 2020.
Technically, UL certification isn’t absolutely required to sell your product in the U.S. But, if the product does plug into an AC electrical outlet you would be crazy to not get this certification.
If your product starts a fire and you don’t have UL certification, you will be held liable.
Even if no one is ever injured by your product, obtaining a UL certification helps you to make a better, safer product.
Passing these various certifications, whether mandatory or not, helps to make your product more robust and less likely to have any problems in the future.
You don’t want to have issues like Samsung’s Galaxy Note 7 phone that was constantly catching on fire. Regardless of the size of your company, recovering from these types of failures can be next to impossible.
UL certification is only necessary for products that plug into an AC power outlet. Most battery powered products need to have their battery recharged at some point with an AC power outlet.
You can avoid this UL certification requirement if your product uses a pre-certified stand-alone charger. One caveat to mention is that this applies to SELV (Safety Extra Low Voltage) circuits.
In a nutshell, that means no operator accessible parts, including the output of the AC adapter, should have a voltage higher than 42.4 VAC peak (30VAC RMS), or 60 VDC.
So, for example, if your product can be recharged by a USB charger, then the UL requirement falls on the charger itself and not necessarily on your product.
In this case you could either purchase a pre-certified USB charger to bundle with your product, or you could require the customer to supply their own USB charging source.
The same is true if your product uses a non-USB charger such as a wall adapter power supply. In this case, once again the UL certification requirement falls on the wall adapter since it plugs directly into the AC electrical outlet.
Your product will never see that AC voltage since the wall adapter converts it down to a low DC voltage.
Most product liability insurance companies, as well as most large retail chains, will require that your product be UL certified even if it doesn’t plug directly into an AC outlet. Larger retailers will require it as an extra margin of safety.
This is one reason that many entrepreneurs begin selling their product directly to consumers via their own website. Doing so may allow you to minimize the number of certifications required.
UL certification can be quite complex and confusing because of the numerous types of UL certifications.
If your product does plug directly into an AC electrical outlet then I highly suggest you bring on a UL expert to review the design before you proceed too far with development.
CE marking is required for the majority of products marketed in Europe.
CE is an abbreviation for the French phrase Conformité Européenne which translates to European Conformity. Originally called an EC Mark, this certification officially became known as a CE Marking in 1993.
The CE marking on a product is a manufacturer’s declaration that the product complies with the health, safety and environmental requirements in Europe. It is quite similar to a combination of the UL and FCC certifications.
If your product contains a battery charger, and will be sold in the state of California, then it must meet the California Energy Commission (CEC) efficiency requirements.
In particular, the AC Adapter must be certified to the DOE (Department of Energy) energy efficiency level VI.
RoHS certification verifies that a product contains no lead, or other harmful substances such as Cadmium and Mercury. RoHS is necessary for products sold in the European Union and the state of California.
Since most products are sold in California and/or Europe, their requirements have become the de-facto standard for environmental regulation.
RoHS is one of the easiest and cheapest types of certifications to obtain. In fact, you may find this is something your contract manufacturer will do for you.
Just make sure that the manufacturer is following the latest amendment of the RoHS 2 standard. Please also note that RoHS encompasses everything in your product, including the screws and enclosure.
Also remember, you don’t want to mix leaded and lead-free components on the same PCB assembly as the reflow profile for each type are incompatible.
That’s why I recommend that from the very beginning you select and work with lead-free components.
Most components are available in leaded and lead-free versions. If you select leaded versions for prototyping and development you will have to go through the time consuming exercise of reworking your Bill of Material for the manufactured product to be RoHS compliant.
WEEE encourages the design of electronic products with environmentally safe recycling and recovery in mind.
This regulation works in conjunction with RoHS. RoHS regulates the hazardous materials used in electronic products, and WEEE regulates the safe disposal of the product.
ElectroStatic Discharge, or ESD, is easily produced and can damage your product. For example, the triboelectric effect of simply walking on a carpet can produce enough static charge to damage sensitive electronic equipment.
While generally not a safety issue, ESD immunity testing is highly recommended. While some ESD induced failures are immediate, others may not manifest for a while.
ESD immunity testing prevents you from encountering problems some time down the road, when a lot of products are already in the field. The cost of finding out that your products are failing at a high rate, especially after the revenue from the sales has been divested, can be devastating.
The accepted test protocol for ESD immunity is the IEC 61000–4–2, with at least Level 2 passing. However, I recommend that you aim for Level 3 or higher.
ESD is usually mitigated through the use of transient voltage suppressors (TVS) on exposed pins, such as USB, of the product. I recommend that you allow some space on the PCB for such components, even if they might prove unnecessary in final product.
Although not technically a certification, if your product incorporates Bluetooth Classic or Bluetooth Low-Energy, then you must have it tested and “certified” in order to use the Bluetooth name/logo on your product.
Bluetooth SIG is a non-profit organization that oversees the Bluetooth standard and the licensing of the Bluetooth technology trademark. You need to register and have your product tested in a certified lab.
You must also pay to use the Bluetooth trademark. Unlike the other certifications, this is an international certification.
If your product implements Bluetooth using a pre-certified module, you still need to obtain the Bluetooth SIG certification.
The normal Bluetooth SIG fee is $8,000 USD. However, they also offer a lower cost option, specifically for start-up companies, that costs only $2,500 USD. To qualify you must show financial documents proving that your annual revenue is less than $1 million dollars.
Some types of products will require even more certifications. For example, toys have a very comprehensive list of required tests and regulations to ensure they are safe for children.
Or, if your product comes into contact with food then you’ll need to follow FDA guidelines on what materials can be safely used.
Because lithium batteries have the potential to cause a fire hazard (think Samsung Galaxy Note 7), there are regulations on the shipment of lithium batteries.
The air shipment of bulk lithium batteries is especially restricted to cargo aircrafts only. Also, if your product contains a large li-ion battery, there are further restrictions based on its Equivalent Lithium Content (ELC).
You don’t want to certify your product too early, because your product will have to be completely retested if any design changes are made.
However, you should plan for certification even during the design phase. For example, make sure to select lead-free components from the start since your final design will be required to meet the RoHS standard.
Testing is expensive and takes up to a month to complete (depending on the testing facility’s queue), so you don’t want to do it more times than is necessary. Wait until you have manufacturing, and most bugs, figured out.
Then, submit a production unit for certification testing. Just be sure to plan for the time that testing and certification will take. You won’t be able to ship your product to customers until the certification is completed.
Regulations often require a copy of your instructions manual to be included along with the units to be tested. So be sure to have your manual finalized before you begin certifications testing.
Regardless of your product, or the countries where it will be sold, you would be very wise to hire someone that is an expert in all the various required certifications.
It is extremely unlikely that your design engineer(s) will have the necessary knowledge to ensure your product smoothly passes all of the various certifications required.
Many startups plan to market their product globally without understanding that they need capital to pay for added regulatory tests for each country.
I highly recommend that you focus your initial efforts on a single country or region, then expand slowly from there.
The USA and Canada share similar certification requirements so in most cases you can sell your product in both countries with a single set of certifications. The EU has the advantage that one set of certification requirements are valid for multiple countries.
Asia on the other hand tends to have separate regulations for each country. Unless you live in Asia, marketing a product there will only be a viable option once you are a significantly sized company with people on the ground there.
Although you don’t want to actually begin the certification process until you have a production-quality unit for testing, it’s still a good idea to understand all the various issues surrounding certifications.
If you need technical engineering support (including on certifications), coaching, training, and resources to help bring a hardware product to market then definitely check out the Hardware Academy.
Organs, muscles and bones are composed of multiple types of cells and tissues that are carefully organized to carry out a specific function. For example, kidneys are able to filter waste from the blood because of how their specialized cells and tissues are arranged. Disrupting this organization dramatically affects how cells and tissues do their job effectively.
Another example is articular cartilage, which exists where bones meet at the joints. This type of cartilage provides a cushioning material to protect the ends of bones and is tightly integrated with bone through a gradient region known as the osteochondral interface?osteo means related to bone, chondral related to cartilage. When articular cartilage is absent or damaged, debilitating pain results.
Unlike some tissues, cartilage cannot regenerate. It lacks blood vessels to support such repair. After injury or damage, cartilage degeneration progresses, leading to osteoarthritis, which affects approximately 27 million Americans.
“Medical intervention is the only way to regenerate osteochondral tissue,” says Lesley Chow, assistant professor of Materials Science & Engineering and Bioengineering at Lehigh University. “To successfully regenerate this cartilage and make it functional, we must consider the fact that function is related to both the cartilage and the bone. If the cartilage doesn’t have a good anchor, it’s pointless. You could regenerate beautiful cartilage, but it won’t last if it isn’t anchored to that bone immediately beneath it.”
This presents a huge engineering challenge, says Chow, as it’s difficult to create one organ made up of two very different tissues. What is needed is a tissue engineering method that respects the multi-component and organizational nature of how tissues form in nature, she says, adding: “Then we’d have the ability to create something that’s durable.”
Chow has taken a major step in the field’s efforts to address such a challenge. She and her team at The Chow Lab at Lehigh have demonstrated a new method to fabricate scaffolds presenting spatially organized cues to control cell behavior locally within one material. Their proof-of-concept paper, published in Biomaterials Science, is called: “3D printing with peptide-polymer conjugates for single-step fabrication of spatially functionalized scaffolds.” This work was led by Lehigh graduate students Paula Camacho (Bioengineering) and Hafiz Busari (Materials Science & Engineering) with co-authors Kelly Seims (Materials Science & Engineering), Peter Schwarzenberg (Mechanical Engineering & Mechanics), and Hannah L. Dailey, assistant professor of Mechanical Engineering and Mechanics at Lehigh. Their publication shows how their platform can be used to create continuous, highly organized scaffolds to regenerate two different tissues, such as those found in the osteochondral interface.
Chow’s lab creates biomaterial scaffolds made of biodegradable polymers, which are long chains of molecules that can degrade over time in the body. Scaffolds are widely-used in tissue engineering to provide cells with structural support, as well chemical cues that “tell” the cells what type of cell to become or tissue to form. Used in the early stages of tissue regeneration, scaffolds are designed to be implanted in the body and then degrade as new tissue forms.
Chow’s team uses 3D printing technology to control the deposition of “inks” with different material compositions. These inks are prepared by mixing a biodegradable polymer with peptide-modified polymers. The peptides, composed of amino acids, provide the bioactive cues to the cells.
“We know from literature and nature what amino acid sequences we want,” says Chow. “We can take a segment that we know plays a specific and important role in telling cells to grow new tissue and, in a sense, steal from Nature. We take a peptide and attach it onto a polymer and add that in while we are constructing our scaffolds. We use 3D printing as a way to control the organization of these peptide-functionalized polymers as well as the scaffold’s architecture.”
Once the team fabricates the scaffold, they “seed” them with cells, such as human mesenchymal stem cells that can be “coaxed” in response to the peptides into becoming different cell types.
As Chow explains, changing the scaffold’s properties is simply a matter of changing the inks loaded in the printer. The team can modify peptide concentration as well as location, and they can do this with more than one ink composition.
“What we are doing is creating an environment that fosters the regeneration of two different tissues simultaneously in one scaffold,” says Chow. “We make a scaffold that has the correct cues?one that promotes cartilage, one that promotes bone?all in one material. You then have a single scaffold where you don’t have to worry about mechanical failure at the interface because you have a single material rather than “gluing” two separate scaffolds together and just hoping for the best.”
In the paper, the authors demonstrate the effectiveness of their method using two very familiar peptides. They describe how peptide-modified polymer conjugates were synthesized with the cell adhesion motif RGDS or its negative control RGES. To demonstrate spatial control of peptide functionalization, multiple printer heads were used to print both conjugates into the same construct in alternating patterns. As designed, cells preferentially attached and spread on RGDS(biotin)-polymer conjugate fibers compared to RGES(azide)-polymer conjugate fibers. This illustrated how spatial peptide functionalization influenced local cell behavior within a single biomaterial. This preferential attachment demonstrates that the technique has real potential for creating scaffolds that enable scientists to direct “where cells are going to stick.”
According to Chow, most scaffold fabrication techniques involve modification after it is created, which can lead to unwanted outcomes, such as the distribution of chemistries in a uniform concentration. Yet, native tissues are not organized this way.
“Our platform is designed to really control how cells arrange themselves,” says Chow. “It’s like building a house and then seeing which house the cells like best. And, we found that the cells really notice. They notice the two different cues. They notice whether the cues are organized or not organized.”
“It is so important for us to have fine-tuned control to make the cells do what we want them to do,” adds Camacho.
One of Camacho’s current projects is applying the team’s scaffold biofabrication platform to engineer osteochondral tissue formation. Camacho and her colleagues culture the cell-seeded scaffolds in an incubator held at body temperature (37?C?or 98.6?F) with 5% carbon dioxide in order to mimic the conditions inside the human body. They evaluate what type of tissue forms and how the cells behave at different points in time. This offers them a glimpse into which scaffolds are most likely to be successful.
“Right now I’m testing two different peptides,” says Camacho. “One is to coax the human mesenchymal stem cells to differentiate into chondrocytes, or cartilage cells. And the other peptide is trying to get them to differentiate into bone. I build these scaffolds with one peptide or both peptides that are organized in different ways. And I want to see how the cells react to it?if they like one more than the other. I characterize what they are doing up to 42 days in culture.”
While the team is working on a few specific projects, including the osteochondral work, their goal is for other researchers to be able to use the platform and, ultimately, to help move the field forward.
“We believe this presents a versatile platform to generate multifunctional biomaterials that can mimic the biochemical organization found in native tissues to support functional regeneration,” says Chow.
Google has made multiple announcements related to AdMob, its mobile app monetization platform. The announcements include a number of enhancements to the AdMob SDK, and a completely new AdMob API. Both the SDK enhancements and the API overhaul focus on improved access to greater insights for AdMob users.
“At AdMob, we’re focused on helping publishers make smarter decisions to grow their mobile app earnings and deliver the best experience to their users,” the AdMob team commented in a blog post announcement. “Clear, comprehensive reporting is a big part of this, and we’ve recently released some updates to our reporting so that you can gain more actionable insights about your app users.”
Historically, developers accessed AdMob stats through the AdSense API. AdSense and AdMob use different ad metrics and definitions. Accordingly, the AdSense API was not an optimal solution for developers. The new AdMob API grants publishers programmatic access to AdMob metrics. The metrics align with the metrics available through the AdMob front-end interface. Google also indicated that reports will be more accurate through the new API. The API is currently in beta, and those interested should reach out to a mobile specialist.
The SDK enhancements focus on better insights. A new user engagement card is available through the App Overview dashboard. The card provides top-line user numbers. Revenue reporting now includes in-app purchases and subscriptions. With the new rewarded ads feature, publishers can better understand how users interact with ads. To enable the new features, users need to update to the latest SDK (Android 18.1.0, iOS 7.44 or later). Additionally, users need to enable user metrics by following a few steps listed in this Help Center Article.
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Author: <a href="https://www.programmableweb.com/user/%5Buid%5D">ecarter</a>
Have you ever needed an IV and had to undergo multiple pricks before the nurse could find a vein? Technology to avoid that painful trial and error is in the works. Fujifilm’s ultrasound diagnostics arm SonoSite announced yesterday that it had partnered with a startup company to develop artificial intelligence that can interpret ultrasound images on a mobile phone.
The companies say the first target for their AI-enabled ultrasound will be finding veins for IV (intravenous) needle insertion. The technology would enable technicians to hold a simple ultrasound wand over the skin while software on a connected mobile device locates the vein for them.
For this project, Fujifilm SonoSite tapped the Allen Institute for Artificial Intelligence (AI2), which has an incubator for AI startup companies. “Not only do we have to come up with a very accurate model to analyze the ultrasound videos, but on top of that, we have to make sure the model is working effectively on the limited resources of an android tablet or phone,” says Vu Ha, technical director of the AI2 Incubator.
In an interview with IEEE Spectrum, Ha did not disclose the name of the startup that will be taking on the task, saying the fledgling company is still in “stealth mode.”
Ha says the AI2 startup will take on the project in two stages: First, it’ll train a model on ultrasound images without any resource constraints, with the purpose of making it as accurate as possible. Then, the startup will go through a sequence of experiments to simplify the model by reducing the number of hidden layers in the network, and by trimming and compressing the network until it is simple enough to operate on a mobile phone.
The trick will be to shrink the model without sacrificing too much accuracy, Ha says.
If successful, the device could help clinicians reduce the number of unsuccessful attempts at finding a vein, and enable less trained technicians to start IVs as well. Hospitals that do a large volume of IVs often have highly trained staff capable of eyeballing ultrasound videos and using those images to help them to find small blood vessels. But the number of these highly trained clinicians is very small, says Ha.
“My hope is that with this technology, a less trained person will be able to find veins more reliably” using ultrasound, he says. That could broaden the availability of portable ultrasound to rural and resource-poor areas.
But the adoption of these devices has been relatively slow. As Eric Topol, director of the Scripps Research Translational Institute, told Spectrum recently, the smartphone ultrasound is a “brilliant engineering advance” that’s “hardly used at all” in the health care system. Complex challenges such as reimbursement, training, and the old habits of clinicians often hinder the uptake of new gadgets, despite engineers’ best efforts.