The key to creating a material that would be ideal for converting solar energy to heat is tuning the material’s spectrum of absorption just right. It should absorb virtually all wavelengths of light that reach Earth’s surface from the sun — but not much of the rest of the spectrum, since that would increase the energy that is reradiated by the material, and thus lost to the conversion process.
Now, researchers at MIT say they have accomplished the development of a material that comes very close to the “ideal” for solar absorption. The material is a two-dimensional metallic dielectric photonic crystal, and has the additional benefits of absorbing sunlight from a wide range of angles and withstanding extremely high temperatures. Perhaps most importantly, the material can also be made cheaply at large scales.
Droplets are simple spheres of fluid, not normally considered capable of doing anything on their own. But now, researchers have made droplets of alcohol move through water. In the future, such moving droplets may deliver medicines.
To be able to move on your own – to be self-moving – is a feature normally seen in living organisms. But also non-living entities can be self-moving, report researchers from Univ. of Southern Denmark and Institute of Chemical Technology in Prague, Czech Republic.
Present-day lithium batteries are efficient but involve a range of resource and environmental problems. Now, using materials from alfalfa and pine resin and a clever recycling strategy, Uppsala researchers have come up with an interesting alternative. Their study will be presented soon in the scientific journal ChemSusChem.
“We think our discovery can open several doors to more environment-friendly, energy-efficient solutions for the batteries of the future,” says Daniel Brandell, Senior Lecturer at the Department of Chemistry, Uppsala Univ., one of the researchers behind the idea.
New Transistor is Big Step for Flexible Electronics
As LG demonstrated this summer, with the unveiling of its 18-inch flexible screen, the next generation of roll-up displays is tantalizingly close. Researchers are now reporting in the journal ACS Nano a new inexpensive and simple way to make transparent, flexible transistors — the building blocks of electronics — that could help bring roll-up smartphones with see-through displays and other bendable gadgets to consumers in just a few years.
Yang Yang and colleagues note that transistors are traditionally made in a multi-step photolithography process, which uses light to print a pattern onto a glass or wafer. Not only is this approach costly, it also involves a number of toxic substances.
Researchers have discovered a way to create a highly sensitive chemical sensor based on the crystalline flaws in graphene sheets. The imperfections have unique electronic properties that the researchers were able to exploit to increase sensitivity to absorbed gas molecules by 300 times. The study is available online in advance of print in Nature Communications.
In many applications, grain boundaries are considered faults because they scatter electrons and may weaken the lattice. But Salehi-Khojin and his colleagues showed that these imperfections are important to the working of graphene-based gas sensors. The team created a micron-sized, individual graphene grain boundary in order to probe its electronic properties and study its role in gas sensing.
Univ. of Minnesota electrical engineering researchers have developed a unique nanoscale device that demonstrates mechanical transportation of light. The discovery could have major implications for creating faster and more efficient optical devices for computation and communication.
The research paper by Univ. of Minnesota electrical and computer engineering assistant professor Mo Li and his graduate student Huan Li has been published online and will appear in the October issue of Nature Nanotechnology.
Shellfish such as mussels and barnacles secrete very sticky proteins that help them cling to rocks or ship hulls, even underwater. Inspired by these natural adhesives, a team of MIT engineers has designed new materials that could be used to repair ships or help heal wounds and surgical incisions.
To create their new waterproof adhesives, the MIT researchers engineered bacteria to produce a hybrid material that incorporates naturally sticky mussel proteins as well as a bacterial protein found in biofilms — slimy layers formed by bacteria growing on a surface. When combined, these proteins form even stronger underwater adhesives than those secreted by mussels.
Researchers at MIT and Northeastern Univ. have equipped a robot with a novel tactile sensor that lets it grasp a USB cable draped freely over a hook and insert it into a USB port.
The sensor is an adaptation of a technology called GelSight, which was developed by the lab of Edward Adelson, the John and Dorothy Wilson Professor of Vision Science at MIT, and first described in 2009. The new sensor isn’t as sensitive as the original GelSight sensor, which could resolve details on the micrometer scale. But it’s smaller — small enough to fit on a robot’s gripper — and its processing algorithm is faster, so it can give the robot feedback in real time.
For future astronauts, the process of suiting up may go something like this: instead of climbing into a conventional, bulky, gas-pressurized suit, an astronaut may don a lightweight, stretchy garment, lined with tiny, muscle-like coils. She would then plug in to a spacecraft’s power supply, triggering the coils to contract and essentially shrink-wrap the garment around her body.
The skintight, pressurized suit would not only support the astronaut, but would give her much more freedom to move during planetary exploration. To take the suit off, she would only have to apply modest force, returning the suit to its looser form.
From the most parched areas of Saudi Arabia to water-scarce areas of the western U.S., the idea of harvesting fog for water is catching on. Now, a novel approach to this process could help meet affected communities’ needs for the life-essential resource. Scientists describe their new, highly efficient fog collector, inspired by a shorebird’s beak, in the journal ACS Applied Materials & Interfaces.
Cheng Luo and his doctoral student, Xin Heng, explain that deserts and semi-arid areas cover about half of the Earth’s land masses. In some of these places, trucks bring in potable water for the people who live there. To find a more sustainable way to get water, these communities, which can’t draw water from underground or surface supplies, have turned to the air — and to nature for inspiration.
Cephalopods, which include octopuses, squid and cuttlefish, are among nature’s most skillful camouflage artists, able to change both the color and texture of their skin within seconds to blend into their surroundings — a capability that engineers have long struggled to duplicate in synthetic materials. Now, a team of researchers has come closer than ever to achieving that goal, creating a flexible material that can change its color or fluorescence and its texture at the same time, on demand, by remote control.
Sharks Inspire Hospital Surfaces to Cut Infections
Transmission of bacterial infections, including MRSA and MSSA could be curbed by coating hospital surfaces with microscopic bumps that mimic the scaly surface of shark skin, according to research published in BioMed Central’s open access journal Antimicrobial Resistance and Infection Control.
The study modeled how well different materials prevented the spread of human disease bacteria through touching, sneezes or spillages. The micro-pattern, named Sharklet, is an arrangement of ridges formulated to resemble shark skin. The study showed that Sharklet harbored 94 percent less MRSA bacteria than a smooth surface, and fared better than copper, a leading antimicrobial material. The bacteria were less able to attach to Sharklet’s imperceptibly textured surface, suggesting it could reduce the spread of superbugs in hospital settings.
Cheetah Robot Can Run, Jump, Untethered, Across Grass
Speed and agility are hallmarks of the cheetah: the big predator is the fastest land animal on Earth, able to accelerate to 60 mph in just a few seconds. As it ramps up to top speed, a cheetah pumps its legs in tandem, bounding until it reaches a full gallop.
Now, MIT researchers have developed an algorithm for bounding that they’ve successfully implemented in a robotic cheetah — a sleek, four-legged assemblage of gears, batteries and electric motors that weighs about as much as its feline counterpart. The team recently took the robot for a test run on MIT’s Killian Court, where it bounded across the grass at a steady clip.
Image of the Week: Approach Creates Strong, Conductive Carbon Threads
The very idea of fibers made of carbon nanotubes is neat, but Rice Univ. scientists are making them neater — literally. The single-walled carbon nanotubes in new fibers created at Rice line up like a fistful of uncooked spaghetti through a process designed by chemist Angel Martí and his colleagues.
The tricky bit, according to Martí, whose lab reported its results this month in the journal ACS Nano, is keeping the densely packed nanotubes apart before they’re drawn together into a fiber. Left to their own devices, carbon nanotubes form clumps that are perfectly wrong for turning into the kind of strong, conductive fibers needed for projects ranging from nanoscale electronics to macro-scale power grids.