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Nordic nRF9160 DK // Unboxing

We check out this cool kit from Nordic: a multi-sensor cellular IoT prototyping platform for hardware engineers. Easily connect Arduino shields and standalone sensors to the nRF Connect for Cloud platform (nrfcloud.com).

Where the Thingy:91 device (previously: https://www.youtube.com/watch?v=tLUKgDT2V9g) comes with built-in sensors and a consumer-ready interface, the nRF9160 DK empowers you to prototype apps with your own custom hardware.

nRF9160 DK materials:
// https://www.nordicsemi.com/Software-and-tools/Development-Kits/nRF9160-DK
// https://www.nordicsemi.com/Products/Low-power-cellular-IoT/nRF9160

Thingy:91 materials:
// https://www.nordicsemi.com/Software-and-tools/Prototyping-platforms/Nordic-Thingy-91/
// https://www.hackster.io/glowascii/getting-started-with-the-nordic-thingy-91-mac-8d44e5

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ScienceDaily

Key advance for printing circuitry on wearable fabrics

Electronic shirts that keep the wearer comfortably warm or cool, as well as medical fabrics that deliver drugs, monitor the condition of a wound and perform other tasks, may one day be manufactured more efficiently thanks to a key advance by Oregon State University researchers.

The breakthrough involves inkjet printing and materials with a crystal structure discovered nearly two centuries ago. The upshot is the ability to apply circuitry, with precision and at low processing temperatures, directly onto cloth — a promising potential solution to the longstanding tradeoff between performance and fabrication costs.

“Much effort has gone into integrating sensors, displays, power sources and logic circuits into various fabrics for the creation of wearable, electronic textiles,” said Chih-Hung Chang, professor of chemical engineering at Oregon State. “One hurdle is that fabricating rigid devices on cloth, which has a surface that’s both porous and non-uniform, is tedious and expensive, requiring a lot of heat and energy, and is hard to scale up. And first putting the devices onto something solid, and then putting that solid substrate onto fabric, is problematic too — it limits the flexibility and wearability of the fabric and also can necessitate cumbersome changes to the fabric manufacturing process itself.”

Chang and collaborators in the OSU College of Engineering and at Rutgers University tackled those challenges by coming up with a stable, printable ink, based on binary metal iodide salts, that thermally transforms into a dense compound of cesium, tin and iodine.

The resulting film of Cs2SnI6 has a crystal structure that makes it a perovskite.

Perovskites trace their roots to a long-ago discovery by a German mineralogist. In the Ural Mountains in 1839, Gustav Rose came upon an oxide of calcium and titanium with an intriguing crystal structure and named it in honor of Russian nobleman Lev Perovski.

Perovskite now refers to a range of materials that share the crystal lattice of the original. Interest in them began to accelerate in 2009 after a Japanese scientist, Tsutomu Miyasaka, discovered that some perovskites are effective absorbers of light. Materials with a perovskite structure that are based on a metal and a halogen such as iodine are semiconductors, essential components of most electrical circuits.

Thanks to the perovskite film, Chang’s team was able to print negative-temperature-coefficient thermistors directly onto woven polyester at temperatures as low as 120 degrees Celsius — just 20 degrees higher than the boiling point of water.

A thermistor is a type of electrical component known as a resistor, which controls the amount of current entering a circuit. Thermistors are resistors whose resistance is temperature dependent, and this research involved negative-temperature-coefficient, or NTC, thermistors — their resistance decreases as the temperature increases.

“A change in resistance due to heat is generally not a good thing in a standard resistor, but the effect can be useful in many temperature detection circuits,” Chang said. “NTC thermistors can be used in virtually any type of equipment where temperature plays a role. Even small temperature changes can cause big changes in their resistance, which makes them ideal for accurate temperature measurement and control.”

The research, which included Shujie Li and Alex Kosek of the OSU College of Engineering and Mohammad Naim Jahangir and Rajiv Malhotra of Rutgers University, demonstrates directly fabricating high-performance NTC thermistors onto fabrics at half the temperature used by current state-of-the-art manufacturers, Chang said.

“In addition to requiring more energy, the higher temperatures create compatibility issues with many fabrics,” he said. “The simplicity of our ink, the process’ scalability and the thermistor performance are all promising for the future of wearable e-textiles.”

The Walmart Manufacturing Innovation Foundation and National Science Foundation supported this study. Findings were published in Advanced Functional Materials.

Story Source:

Materials provided by Oregon State University. Original written by Steve Lundeberg. Note: Content may be edited for style and length.

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Power-free system harnesses evaporation to keep items cool

Camels have evolved a seemingly counterintuitive approach to keeping cool while conserving water in a scorching desert environment: They have a thick coat of insulating fur. Applying essentially the same approach, researchers at MIT have now developed a system that could help keep things like pharmaceuticals or fresh produce cool in hot environments, without the need for a power supply.

Most people wouldn’t think of wearing a camel-hair coat on a hot summer’s day, but in fact many desert-dwelling people do tend to wear heavy outer garments, for essentially the same reason. It turns out that a camel’s coat, or a person’s clothing, can help to reduce loss of moisture while at the same time allowing enough sweat evaporation to provide a cooling effect. Tests have showed that a shaved camel loses 50 percent more moisture than an unshaved one, under identical conditions, the researchers say.

The new system developed by MIT engineers uses a two-layer material to achieve a similar effect. The material’s bottom layer, substituting for sweat glands, consists of hydrogel, a gelatin-like substance that consists mostly of water, contained in a sponge-like matrix from which the water can easily evaporate. This is then covered with an upper layer of aerogel, playing the part of fur by keeping out the external heat while allowing the vapor to pass through.

Hydrogels are already used for some cooling applications, but field tests and detailed analysis have shown that this new two-layer material, less than a half-inch thick, can provide cooling of more than 7 degrees Celsius for five times longer than the hydrogel alone — more than eight days versus less than two.

The findings are being reported today in a paper in the journal Joule, by MIT postdoc Zhengmao Lu, graduate students Elise Strobach and Ningxin Chen, Research Scientist Nicola Ferralis and Professor Jeffrey Grossman, head of the Department of Materials Science and Engineering.

The system, the researchers say, could be used for food packaging to preserve freshness and open up greater distribution options for farmers to sell their perishable crops. It could also allow medicines such as vaccines to be kept safely as they are delivered to remote locations. In addition to providing cooling, the passive system, powered purely by heat, can reduce the variations in temperature that the goods experience, eliminating spikes that can accelerate spoilage.

Ferralis explains that such packaging materials could provide constant protection of perishable foods or drugs all the way from the farm or factory, through the distribution chain, and all the way to the consumer’s home. In contrast, existing systems that rely on refrigerated trucks or storage facilities may leave gaps where temperature spikes can happen during loading and unloading. “What happens in just a couple of hours can be very detrimental to some perishable foods,” he says.

The basic raw materials involved in the two-layer system are inexpensive — the aerogel is made of silica, which is essentially beach sand, cheap and abundant. But the processing equipment for making the aerogel is large and expensive, so that aspect will require further development in order to scale up the system for useful applications. But at least one startup company is already working on developing such large-scale processing to use the material to make thermally insulating windows.

The basic principle of using the evaporation of water to provide a cooling effect has been used for centuries in one form or another, including the use of double-pot systems for food preservation. These use two clay pots, one inside the other, with a layer of wet sand in between. Water evaporates from the sand out through the outer pot, leaving the inner pot cooler. But the idea of combining such evaporative cooling with an insulating layer, as camels and some other desert animals do, has not really been applied to human-designed cooling systems before.

For applications such as food packaging, the transparency of the hydrogel and aerogel materials is important, allowing the condition of the food to be clearly seen through the package. But for other applications such as pharmaceuticals or space cooling, an opaque insulating layer could be used instead, providing even more options for the design of materials for specific uses, says Lu, who was the paper’s lead author.

The hydrogel material is composed of 97 percent water, which gradually evaporates away. In the experimental setup, it took 200 hours for a 5-millimeter layer of hydrogel, covered with 5 millimeters of aerogel, to lose all its moisture, compared to 40 hours for the bare hydrogel. The two-layered material’s cooling level was slightly less — a reduction of 7 degrees Celsius (about 12.6 degrees Fahrenheit) versus 8 C (14.4 F) — but the effect was much longer-lasting. Once the moisture is gone from the hydrogel, the material can then be recharged with water so the cycle can begin again.

Especially in developing countries where access to electricity is often limited, Lu says, such materials could be of great benefit. “Because this passive cooling approach does not rely on electricity at all, this gives you a good pathway for storage and distribution of those perishable products in general,” he says.

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How weather news impacts public transit ridership

If the words in a weather forecast, such as “cool,” “sunny” or “windy,” can influence the way you dress for the day — can they also influence whether or not you take public transit?

In new research published in Vehicles, U researchers found a correlation between words used in media coverage related to weather or air quality, and transit ridership. It’s not enough yet to say that media coverage causes changes in ridership, say authors Tabitha Benney and Daniel Mendoza. But it’s enough to explore what factors in to a person’s decision to ride transit and whether that decision can be nudged.

“This is encouraging,” Benney says. “There’s a lot of potential in terms of reaching a lot of different actors that could have a big influence or encourage ridership.”

Scanning the media

Mendoza, a research assistant professor in the Department of Atmospheric Sciences and visiting assistant professor in the Department of City & Metropolitan Planning, previously studied how transit ridership along the Wasatch Front, on the buses and trains of the Utah Transit Authority (UTA), impacted air quality. The impact is greater when more people are riding since low-ridership trips, particularly on older buses, can actually have a net contribution to air pollution.

Around the same time Tabitha Benney, an associate professor in the Department of Political Science, was looking at surveys of Utahns that included their reasons for using transit or not. “We were surprised at some of the responses,” she says, “and that led me to pursue asking questions about what matters in terms of what could be in the media or how it could be influencing people.”

So Mendoza and Benney, along with co-authors Martin Buchert and John Lin, looked at how media coverage of the weather and air quality correlated with transit ridership. For the years 2014-2016, they scanned 40 local Utah media outlets for words related to weather (such as “cloudy,” “freezing,” or “summer”), air quality (red, yellow or green air day, according to the state’s color-coded air quality system) and air pollution (such as “ozone,” “PM2.5” or “particulate matter”). Then they looked at the transit ridership the day after the media coverage and noted the actual air quality of that day.

“We wanted to ask if there are any additional factors that would encourage or discourage ridership,” Mendoza says.

Comfort and safety

UTA has three main modes of transportation: buses, light rail (TRAX) and commuter rail (FrontRunner). FrontRunner riders tend to ride for farther distances, and their rider behavior, the authors found, didn’t vary much with media terms. The most variation, they found, was in bus ridership.

Within that variation, a few media terms related to weather stood out. On average, more usage of the term “good weather” was correlated with more ridership the following day. Similarly, more usage of “winter” was associated with increased ridership, but that may be related to the seasonal nature of U students, the authors say, as the U is the single largest paid pass purchaser from UTA.

Few UTA bus stops have a weather shelter, Mendoza says (although UTA has added more shelters in recent years). Media reports of bad weather, he suggests, could discourage bus ridership.

When looking at color-coded air quality terms, the researchers found less ridership on the bus system on days following use of “orange air day” and “red air day.” That could be due to non-commuter bus users who ride the bus for discretionary transportation choosing to stay home to avoid poor air quality and the cold temperatures that typically accompany poor air quality days.

“Ridership is associated with favorable weather conditions and air quality,” the authors wrote, “suggesting that ridership volume may be influenced by an overall sense of comfort and safety.”

They also found that less technical terms, such as “particulate matter” instead of “PM2.5,” were correlated with greater changes in ridership. Same with the color-coded “red air day” term.

“That kind of surprised us,” Benney says. Another surprise was the finding that reports of bad air quality reduced ridership, and that reports of good air quality didn’t boost it.

“You would expect a strong relationship to clean air with people wanting to move in that direction,” she says. “And that’s obviously significant.”

Moving the needle

Benney says that the study focused on web-accessible media outlets and did not take into account social media, which could have a significant influence on younger audiences, who tend to ride buses more. Upcoming work, she says, will look closer at the sources of Utahns’ information about weather and air quality, including from religious services.

The study is encouraging, she adds, because it suggests that messages may be able to influence day-to-day rider behavior. “This opens up a lot of opportunities for large institutional actors to help promote better air quality through ridership,” she says.

And the impact has already begun. The Utah Legislature passed a bill in 2019 that launched a three-year pilot program to provide free fares on UTA transit on poor air quality days. Preliminary findings from this research, Mendoza says, provided part of the bill’s supporting scientific basis.

Additionally, he says, some of the largest employers in the Salt Lake Valley, including the University of Utah, may be able to use these findings to effectively encourage employees to make air-friendly choices through riding transit or choosing to telework. “And now we’re all getting really used to telework!” he says. “Because of that we can actually start to potentially move the needle by reducing the vehicular traffic.”

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Getting Started in Hardware

So you’re interested in electronics? Awesome! But how do you actually get started building those cool gadgets like you see on the internet? We’ve got you covered. These resources introduce you to electronic components, what they’re for, and how to use them.

// Hardware 101 tutorial series: https://www.hackster.io/hardware-101
// FYI explainers: https://www.youtube.com/playlist?list=PLsRBa4uXjihb0_6RA5UPMDdWdoEyDlSu1
// Micro:bit Basics for Teachers: https://www.youtube.com/watch?v=RkWDYTx_mg4
// Book recommendations: https://www.hackster.io/news/getting-started-in-electronics-read-these-597953150c42
// Tangible circuits: https://www.youtube.com/watch?v=tjyNQyQ1OB8

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M5Stick-C: First Steps

Learn how to use this cool, wearable, ESP32-based IoT device!

// Intro: https://www.youtube.com/watch?v=uxbMLisBBt4
// https://m5stack.com/products/stick-c
// https://www.thingiverse.com/search?q=m5stick&type=things&sort=relevant
// https://github.com/m5stack/M5StickC
// https://www.hackster.io/glowascii/first-steps-with-m5stick-c-74804c
// https://pulsesensor.com/

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Octopus-inspired robot can grip, move, and manipulate a wide range of objects

Of all the cool things about octopuses (and there’s a lot), their arms may rank among the coolest.

Two-thirds of an octopus’s neurons are in its arms, meaning each arm literally has a mind of its own. Octopus arms can untie knots, open childproof bottles, and wrap around prey of any shape or size. The hundreds of suckers that cover their arms can form strong seals even on rough surfaces underwater.

Imagine if a robot could do all that.

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Beihang University have developed an octopus-inspired soft robotic arm that can grip, move, and manipulate a wide range of objects. Its flexible, tapered design, complete with suction cups, gives the gripper a firm grasp on objects of all shapes, sizes and textures — from eggs to iPhones to large exercise balls.

“Most previous research on octopus-inspired robots focused either on mimicking the suction or the movement of the arm, but not both,” said August Domel, a recent PhD graduate of Harvard and co-first author of the paper. “Our research is the first to quantify the tapering angles of the arms and the combined functions of bending and suction, which allows for a single small gripper to be used for a wide range of objects that would otherwise require the use of multiple grippers.”

The research is published in Soft Robotics.

The researchers began by studying the tapering angle of real octopus arms and quantifying which design for bending and grabbing objects would work best for a soft robot. Next, the team looked at the layout and structure of the suckers (yes, that is the scientific term) and incorporated them into the design.

“We mimicked the general structure and distribution of these suckers for our soft actuators,” said co-first author Zhexin Xie, a PhD student at Beihang University. “Although our design is much simpler than its biological counterpart, these vacuum-based biomimetic suckers can attach to almost any object.”

Xie is the co-inventor of the Festo Tentacle Gripper, which is the first fully integrated implementation of this technology in a commercial prototype.

Researchers control the arm with two valves, one to apply pressure for bending the arm and one for a vacuum that engages the suckers. By changing the pressure and vacuum, the arm can attach to an object, wrap around it, carry it, and release it.

The researchers successfully tested the device on many different objects, including thin plastic sheets, coffee mugs, test tubes, eggs, and even live crabs. The tapering also allowed the arm to squeeze into confined spaces and retrieve objects.

“The results from our study not only provide new insights into the creation of next-generation soft robotic actuators for gripping a wide range of morphologically diverse objects, but also contribute to our understanding of the functional significance of arm taper angle variability across octopus species,” said Katia Bertoldi, the William and Ami Kuan Danoff Professor of Applied Mechanics at SEAS, and co-senior author of the study.

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Sock Puppet Robot, Pt. 1

Time to build a new bot! Alex has been wanting to make a sock-puppet robot, to show off all the cool socks people are giving away as swag nowadays. We’re starting with a base of Adafruit parts and programming in CircuitPython; let’s see how it’s coming together!

// https://www.hackster.io/videos/524
// https://www.adafruit.com/adabox
// https://www.adafruit.com/product/154
// https://learn.adafruit.com/adafruit-crickit-creative-robotic-interactive-construction-kit/recommended-servos
// https://www.hackster.io/glowascii

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Multimaterial 3D printing manufactures complex objects, fast

3D printing is super cool, but it’s also super slow — it would take 115 days to print a detailed, multimaterial object about the size of a grapefruit. A new method allows printing with up to 8 different inks in a fraction of the time, thanks to special printheads that can seamlessly switch inks up to 50 times per second.

3D printers are revolutionizing manufacturing by allowing users to create any physical shape they can imagine on-demand. However, most commercial printers are only able to build objects from a single material at a time and inkjet printers that are capable of multimaterial printing are constrained by the physics of droplet formation. Extrusion-based 3D printing allows a broad palette of materials to be printed, but the process is extremely slow. For example, it would take roughly 10 days to build a 3D object roughly one liter in volume at the resolution of a human hair and print speed of 10 cm/s using a single-nozzle, single-material printhead. To build the same object in less than 1 day, one would need to implement a printhead with 16 nozzles printing simultaneously!

Now, a new technique called multimaterial multinozzle 3D (MM3D) printing developed at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS) uses high-speed pressure valves to achieve rapid, continuous, and seamless switching between up to eight different printing materials, enabling the creation of complex shapes in a fraction of the time currently required using printheads that range from a single nozzle to large multinozzle arrays. These 3D printheads themselves are manufactured using 3D printing, enabling their rapid customization and facilitating adoption by others in the fabrication community. Each nozzle is capable of switching materials at up to 50 times per second, which is faster than the eye can see, or about as fast as a hummingbird beats its wings. The research is reported in Nature.

“When printing an object using a conventional extrusion-based 3D printer, the time required to print it scales cubically with the length of the object, because the printing nozzle has to move in three dimensions rather than just one,” said co-first author Mark Skylar-Scott, Ph.D., a Research Associate at the Wyss Institute. “MM3D’s combination of multinozzle arrays with the ability to switch between multiple inks rapidly effectively eliminates the time lost to switching printheads and helps get the scaling law down from cubic to linear, so you can print multimaterial, periodic 3D objects much more quickly.”

The key to MM3D printing’s speedy ink-switching is a series of Y-shaped junctions inside the printhead where multiple ink channels come together at a single output nozzle. The shape of the nozzle, printing pressure, and ink viscosity are all precisely calculated and tuned so that when pressure is applied to one of the “arms” of the junction, the ink that flows down through that arm does not cause the static ink in the other arm to flow backwards, which prevents the inks from mixing and preserves the quality of the printed object. By operating the printheads using a bank of fast pneumatic valves, this one-way flow behavior allows the rapid assembly of multimaterial filaments that flow continuously out from each nozzle, and enables the construction of a 3D multimaterial part. The length of the ink channels can also be adjusted to account for materials that have different viscosities and yield stresses, and thus flow more quickly or slowly than other inks.

“Because MM3D printing can produce objects so quickly, one can use reactive materials whose properties change over time, such as epoxies, silicones, polyurethanes, or bio-inks,” said co-first author Jochen Mueller, Ph.D., a Research Fellow at the Wyss Institute and SEAS. “One can also readily integrate materials with disparate properties to create origami-like architectures or soft robots that contain both stiff and flexible elements.”

To demonstrate their technique, the researchers printed a Miura origami structure composed of stiff “panel” sections connected by highly flexible “hinge” sections. Previous methods of building such a structure require manually assembling them together into stacked layers — the MM3D printhead was able to print the entire object in a single step by using eight nozzles to continuously extrude two alternating epoxy inks whose stiffnesses differed by four orders of magnitude after being cured. The hinges withstood over 1,000 folding cycles before failing, indicating the high quality of the transitions between the stiff and flexible materials achieved during printing.

MM3D printing can also be used to create more complex objects, including actuating robots. The research team designed and printed a soft robot composed of rigid and soft elastomers in a millipede-like pattern that included embedded pneumatic channels that enable the soft “muscles” to be compressed sequentially by a vacuum, making the robot “walk.” The robot was able to move at nearly half an inch per second while carrying a load eight times its own weight, and could be connected to other robots to carry heavier loads.

“This method enables the rapid design and fabrication of voxelated matter, which is an emerging paradigm in our field,” said corresponding author Jennifer A. Lewis, Sc.D., who is a Core Faculty Member at the Wyss Institute and the Hansjörg Wyss Professor of Biologically Inspired Engineering at SEAS. “Using our broad palette of functional, structural, and biological inks, disparate materials can now be seamlessly integrated into 3D-printed objects on-demand.”

Importantly, current MM3D printheads can only print periodic (i.e., repeating) parts. But the team envisions that MM3D printing will continue to evolve, eventually featuring nozzles that can extrude different inks at different times, smaller nozzles for greater resolution, and even larger arrays for rapid, single-step 3D printing at a wide range of size and resolution scales. They are also exploring the use of sacrificial inks to create even more complex shapes.

“3D printing is revolutionizing the manufacturing industry by allowing people to create without the need for expensive machinery and raw materials, and this new advance promises to dramatically improve the pace of innovation in this exciting area,” said Wyss Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS.

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This Data Logger Discovers What Happens When You Open Your Fridge

Every time you open the refrigerator door, you’re letting cool air out , which has to be pumped back into the cooling chamber via a compressor. Perhaps counter-intuitively, the net effect is that you’re warming your house up since the heat technically has to be pumped out of the fridge using extra energy, though the instant blast of cool air can certainly be refreshing during the summer. Although cold air does escape, the real point it to keep food cold and hopefully unspoiled, and the food and drink would normally have more thermal mass than the air anyway, taking much longer to heat up.

All that to say, while you should close the fridge door ASAP, you may not have a good understanding of the actual effect of doing so. Rather than accept this situation, Ryan Bates decided to actually log what happens when he leaves the fridge open too long. For this experiment, he used a DHT22 sensor to log temperature and humidity. He found that upon opening the door — sensed and recorded with a photoresistor — the humidity immediately spikes, while there is a more subtle change in temperature.

Finally, Bates used TMP36 sensors placed at different locations in the fridge, including taped to a pickle jar. What he found after examining the log, was that the jar only heated up around 1 degree (F) per second of the door being open. Maybe it’s not critical that you immediately slam the door shut as you previously thought. If you’d like to duplicate the experiment yourself, or even take thanks further, code and the circuit used are available here.

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Author: Jeremy S. Cook