How to build millions of tiny microscopes all at once

microscope illustration

A new optical device made of silicon “nanopillars” could lead to advanced microscopes, displays, sensors, and cameras that can be mass-produced using the same techniques used to manufacture computer microchips.

“Currently, optical systems are made one component at a time, and the components are often manually assembled,” says Andrei Faraon, an assistant professor of applied physics and materials science at Caltech. “But this new technology is very similar to the one used to print semiconductor chips onto silicon wafers, so you could conceivably manufacture millions of systems such as microscopes or cameras at a time.”

Seen under a scanning electron microscope, the new metasurfaces that the team created resemble a cut forest where only the stumps remain. Each silicon stump, or pillar, has an elliptical cross section, and by carefully varying the diameters of each pillar and rotating them around their axes, the scientists were able to simultaneously manipulate the phase and polarization of passing light.

[Slinky hyperlens lets us see super tiny things]

Light is an electromagnetic field, and the field of single-color, or monochromatic, light oscillates at all points in space with the same frequency but varying relative delays, or phases. Manipulating this relative delay, or phase, influences the degree to which a light ray bends, which in turn influences whether an image is in or out of focus.

Polarization refers to the trajectory of the oscillations of the electromagnetic field at each point in space. Manipulating the polarization of light is essential for the operation of advanced microscopes, cameras, and displays; the control of polarization also enables simple gadgets such as 3-D glasses and polarized sunglasses.

“Using our metasurfaces, we have complete control of the polarization and phase of light,” says Amir Arbabi, a senior researcher at Caltech and first author of the study published in Nature Nanotechnology. “We can take any incoming light and shape its phase and polarization profiles arbitrarily and with very high efficiency.”

Much thinner than a human hair

While the same goal can be achieved using an arrangement of multiple conventional optical components such as glass lenses, prisms, spatial light modulators, polarizers, and wave plates, these many components lead to much bulkier systems.

“If you think of a modern microscope, it has multiple components that have to be carefully assembled inside,” Faraon says. “But with our platform, we can actually make each of these optical components and stack them atop one another very easily using an automated process. Each component is just a millionth of a meter thick, or less than a hundredth of the thickness of a human hair.”

[Whoa: Fish’s ‘polarized ornaments’ are a real turn-on]

In addition to being compact, a metasurface device could manipulate light in novel ways that are very hard and sometimes impossible to do using current setups.

For example, the Caltech team showed that one of their metasurfaces can project one image when illuminated by a horizontally polarized beam of light, and a different image when illuminated by a vertically polarized beam. “The two images will appear overlapped under illumination with light polarized at 45 degrees,” Faraon says.

Miniature cameras and more

In another experiment, the team was able to use a metasurface to create a beam with radial polarization, that is, a beam whose polarization is pointing toward the beam axis. Such beams have doughnut-shaped intensity profiles and have applications in superresolution microscopy, laser cutting, and particle acceleration.

“You generally would need a large optical setup, consisting of multiple components, to create this effect using conventional instruments,” Arbabi says. “With our setup, we can compress all of the optical components into one device and generate these beams with higher efficiency and more purity.”

[Thinnest-ever imaging platform from this new material]

The team is currently working with industrial partners to create metasurfaces for use in commercial devices such as miniature cameras and spectrometers, but a limited number have already been produced for use in optical experiments by collaborating scientists in other disciplines.

In addition, the Faraon lab current is investigating ways to combine different metasurfaces to create functioning optical systems and to correct for color distortions and other optical aberrations.

“Like any optical system, you get distortions,” Faraon says. “That’s why expensive cameras have multiple lenses inside. Right now, we are experimenting with stacking different metasurfaces to correct for these aberrations and achieve novel functionalities.”

Source: Caltech

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Drought could turn millet into American food

millet in bowl

Most people in the US put millet in the birdfeeder, but Amrita Hazra says we ought to eat it ourselves.

Hazra, a postdoctoral researcher in the University of California, Berkeley, plant and microbial biology department, and her colleagues on the Millet Project are cultivating millets, testing millet recipes, and offering samples of millet-based products at local food events and exhibits.

University writer Gretchen Kell spoke with Hazra about the intersection between science and food, what’s so special about millet, and why California is the perfect place to grow it.

What is millet, or is it millets? And isn’t it just for the birds?

Millet is the name of a type of grain crop that’s been a staple food for humans in many parts of the world. You say millets when referring to the different types of millet species. And yes, in the United States, indeed, millets are primarily used in grain mixes for various kinds of birds, and they’re also forage crops for cattle and poultry. Today, despite being lesser known in Western society, millets are widely cultivated and consumed in many countries in Africa (Ethiopia, Tanzania, Nigeria) and Asia (India, China).

Millets are among the oldest of cultivated grain crops and yet many people haven’t heard about them. Before the popularity of rice, corn, and wheat, millet was a staple food, especially in the semi-arid regions of South and East Asia, Africa, and parts of Europe. In China, records of domestication of foxtail millet and proso millet date back to approximately 10,000 years ago.

The five millet species commonly grown as commercial crops are proso, foxtail, pearl, Japanese barnyard, and browntop—although there are many other types. Proso millet was introduced into the United States from Europe during the 18th century. Today, Colorado is the major US producer, followed by the Dakotas and Nebraska.

What’s so great about millet?

The drought in California is in its fourth year and has brought growers, consumers, policymakers, and food activists together. The importance of diversity in agriculture and in the food we consume is becoming apparent—we shouldn’t be only growing water-intensive monocultures. Millets are robust dryland crops—many millet varieties are inherently drought-tolerant.

[Why record drought is burning California to a crisp]

Millets also are nutritious whole grains that are gluten-free. Different members of the millet family contain different portfolios of nutrients—millet grains often contain lower carbohydrates as compared to rice, corn, or wheat, and higher levels of proteins, fiber, and certain minerals such calcium, magnesium, phosphorous, and iron.

Millets can be grown from seed quite easily at higher temperatures, can grow in skeletal soils and seldom require synthetic fertilizers. They have a short growing period of 100 to 110 days from seed to grain, and as a result are commonly used as rotation crops between the growth of the other crops. Most millet grains are not easily affected by storage pests. And I could go on!

Where does your interest in millet come from?

I grew up in Pune, India, where my brother and I were raised with science as a lifestyle rather than a subject of study. My father is an organic chemist, and my mother is a plant biologist and biochemist. Our dinner table conversations often evolved informally into extended discussions about the connections between chemistry, plants, biology, and food policy.

My mother is also a keen kitchen scientist and always inquires about the whats and whys of the science of the food while she cooks. For example, what factors contribute to the uniform puffing of a roti, an Indian wheat flatbread similar to a tortilla when half cooked on a pan and the finished by putting over an open fire? Is it the proportion of ingredients and process of kneading the dough, the way the flatbread is rolled or the heat retention capacity of the pan’s material? It is yet unknown.

[Pearl millet with extra iron could fight anemia]

My father’s family members were farmers, and our annual visits to his village in rural West Bengal sparked my curiosity about farming and where our food comes from. My interest in millets was triggered by the availability of various types of grains and lentils in my hometown of Pune. Even when I was growing up, rice and wheat were staples in India, but occasional trips to the many farmers’ markets in the city opened my eyes and mind to the true grassroot level meaning of food diversity.

Why is California a perfect place to grow millets?

California is in a drought. And given that a large percentage of the state’s water goes toward agriculture, growing drought-tolerant crops such as millets is a natural first step to diversify agriculture. Growing up in India, I remember eating a type of meal called a “thali.” A thali typically contains between eight and 12 different small portions of vegetable-, lentil-, cereal-, and meat-based foods.

The idea is to have small portions of a variety of foods to keep a sustained intake of nutrients and micronutrients. But in the United States, growers are mainly cultivating monocultures of a few types of crops, and this is reflected on supermarket shelves and on our plates—big portions of a very small variety of food crops.

Introducing diversity in agriculture in California will be a big step and a model for changing the mindsets of growers and consumers in other parts of the country. The movement has begun—the United Nations recently noted that 2016 will be the “International Year of the Pulses” (beans, peas, lentils, and chickpeas), the UN’s Food and Agriculture Organization declared quinoa as the grain of the year in 2013, and the Whole Grains Council has celebrated millet and teff (a cereal grain native to northeastern Africa, also a minor millet) as a grain of the month.

What kinds of food and drink can be made with millet?

Millet is a staple in many cultures, and there is a rich pool of traditional recipes available from Africa, Asia, and Europe. Teff is used for making injera bread in Ethiopia, pearl millet is used in India for bhakri bread, and proso millet is used in regional cuisine in Europe, to make sausages in Austria, and in a breakfast porridge called kasha in Russia and uji in Kenya.

[Hotter climate could ‘wilt’ wheat crops]

However, we had to do homework to see how to incorporate millet into our modern diets. We’ve learned that one can substitute millet for ingredients like rice, oats, quinoa, and couscous in recipes for risotto, porridge, tabouleh, salads, and pilaf. You can see some of the recipes we have catalogued on our Millet Project website.

Also, millets already are in some gluten-free products at the market such as bread and pancake mixes, tortilla chips, and beer. If anyone tries using millet in a recipe and likes it, email us, and we’ll put the recipe on our website!

What’s the Millet Project?

The Millet Project team’s goal is to diversify agriculture and our diets by cultivating and consuming these lesser-known grains called millets. Corn, wheat, and rice comprise at least 80 percent of worldwide cereal production, in spite of the large variety of cereals traditionally available in different parts of the world. This has caused losses in the variety of food and, consequently, the nutrients in our diet, which together have adverse environmental and nutritional impacts.

We have millets currently being farmed in six locations in Northern California. The six of us [in the Millet Project] are the interface between the farmers and consumers; we’re trying to learn from and with these farmers about the different geographical, ecological and soil-related factors that influence millet farming in California.

We also have our own little plot at the Gill Tract Farm where we are doing some preliminary research on how to grow millets under different conditions. We’re growing four different types—foxtail, pearl, proso, and Japanese barnyard. So far, proso is the only millet currently available for sale for human consumption in the United States, and we want to expand that.

Source: UC Berkeley

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Whooper Swan (Cygnus cygnus) in winter

Swan’s springy neck inspires better drone cameras

whooper crane in flight

Swans and geese are the envy of aeronautical engineers. Even plump geese can perform remarkable aerial acrobatics—twisting their body and flapping their powerful wings while keeping their head completely still.

Now, engineers have used high-speed video footage and computer models to reveal that whooper swans stabilize their head with a complex neck that’s tuned like a car suspension.

Their findings have influenced a new design of a camera suspension system that could allow drones to record steadier video.

All birds have built-in vision stabilization to compensate for the up and down body motion caused by flapping their wings in flight. Scientists have studied the neck morphology and head motions of walking or stationary birds, but measuring the mechanism in flight has not been successful until now.

[Do bug wings work like gyroscopes?]

For a new study, published in Journal of the Royal Society Interface, researchers devised a method for comparing high-speed video data of a whooper swan flying over a lake with a computer model that approximated the springy damping effects of the bird’s neck that allow it to stabilize the vertical disturbances.

They found the neck functions much like how a car’s suspension system provides a smooth ride over a bumpy road. The neck vertebrae and muscles respond with just the right stiffness and flexibility to passively keep the head steady during flapping flight, and even in mild gusts.

“This simple mechanism is a remarkable finding considering the daunting complexity of avian neck morphology with about 20 vertebrae and more than 200 muscles on each side,” says David Lentink,  assistant professor of mechanical engineering at Stanford University.

Lentink credits much of the work to a former master’s student, Ashley Pete, who is first author on the study. She developed the idea and methodology for the study in Lentink’s class, ME 303: Biomechanics of Flight.

[drones safely deliver blood samples]

“The paper she wrote for this class was so good that we expanded it together and submitted it to Interface, where it got published,” Lentink says. “This really shows students can make remarkable discoveries in the classroom, going beyond textbooks, based on their creativity and enthusiasm.”

The focus of Lentink’s lab group spans biology and engineering, with goals of improving drone design and performance by understanding and adopting key characteristics from flying birds.

The current work has provided guidelines for a prototype swan-inspired passive camera suspension system, developed by Marina Dimitrov, one of Lentink’s undergraduate students, that could allow drones with flapping wings to record better video.

Source: Stanford University

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Review: Second coming of the q-Jays earphones

q-Jays are described as the world's smallest earphones with detachable cables

In a market saturated with celebrity endorsements, fashion experiments and ambitious mark-ups, it is always a delight to discover a product that focusses on functionality and performance. Swedish company Jays last month released its second-generation q-Jays reference earphones, three years after the release of the first model. We put them through their paces to see if they impress as much as the originals.

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Danish astronaut to control earthbound rover from ISS

ESA's Interact Centaur rover, developed for telerobotics experiments

Working outside in space is a tall order. The environment is hostile, even the smallest job takes hours instead of minutes, and everything has to be done in either bulky suits or through robotic arms. It’s a challenge that will become even more difficult when future astronauts are controlling robotic rovers from orbit, so ESA is getting in a bit of practice. Next month Danish astronaut Andreas Mogensen will take control of a rover in the Netherlands while orbiting the Earth aboard the International Space Station.

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Shape-shifting navigation device points you in the right direction

The Animotus changes shape to point you in the right direction

Even in today’s GPS-enabled world, asking someone to point you in the right direction can often be easier than wrestling with your smartphone. Enter the Animotus, a wirelessly-connected, 3D printed cube that acts like a sort of haptic compass. Developed by Yale engineer Adam Spiers, the device literally changes shape to point you in the right direction…
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LG adds 23-karat bling to Watch Urbane for limited Luxe edition

LG is aiming for the luxury watch market with its latest wearable variant

With a fairly large footprint, the LG Watch Urbane doesn’t exact fly under the radar, but the new model – the Watch Urbane Luxe – makes it look understated. Made in collaboration with Reeds Jewelers, the limited edition version of the wearable ups the ante when it comes to build materials, with a 23-karat gold case.

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Bioengineered heart tissue can be stuck together like Velcro

T-shaped posts allow layers of a scaffold for growing heart tissue to join together like Velcro

A new system for growing heart tissue in the lab may make future heart, liver, and lung repair much easier. University of Toronto scientists have developed asymmetrical honeycomb-shaped 2D meshes of protein scaffolding that stick together like Velcro and imitate the environments in which tissue and muscle cells grow in the body.

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Android Wear invades the Apple Watch's turf: New models will work with iPhones

The Huawei Watch (pictured) will be one of the first Android Wear watches to work with iPhones

The Apple Watch just got some big competition. Android Wear watches, which were previously only compatible with Android phones, will start working with iPhones moving forward.

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Atlas Erida lightweight drone is built to stay airborne longer

Erida takes off automatically

In the drone photography world, names like Parrot and DJI (maker of the Phantom
series) are the closest things to a gold standard at the moment.
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smartphone-controlled, lightweight carbon fiber drone that improves on
battery life by as much as 40 percent.

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