Swiss scientists are helping harness the excess heat generated by subway systems into usable energy, researchers in Washington are testing out technology for proto-telepathic communication, and a set of smart glasses under development at Stanford might work way better than progressive lenses for folks with age-related visual impairment. Get a glimpse of a fascinating future in this week’s coolest scientific discoveries.
“Our research shows that fitting the heat-recovery system along 50–60% of the planned route — or 60,000 square meters of tunnel surface area — would cover the heating needs of 1,500 standard 80m2 apartments,” says researcher Margaux Peltier. Illustration credit: LMS / 2019 EPFL.
What is it? As residents, visitors, and Marilyn Monroe all know, one of those truly magical New York experiences is the warm blasts of dubious-smelling air you encounter blowing up through subway grates while you walk down a busy city sidewalk. Now researchers at the Soil Mechanics Laboratory of Switzerland’s École Polytechnique Fédérale de Lausanne have taken a big step toward harnessing the heat trapped in rail tunnels for a more useful purpose: energy.
Why does it matter? That subterranean heat comes from the braking and acceleration of trains as well as from air-conditioning and the ground itself. Capturing it with a heat-recovery system could help cities reduce their CO2 emissions, explained Margaux Peltier, who with her colleagues calculated the potential benefits for a planned metro tunnel in Lausanne: “Our research shows that fitting the heat-recovery system along 50–60% of the planned route — or 60,000 square meters of tunnel surface area — would cover the heating needs of 1,500 standard 80m2 apartments…Switching from gas-fired heating would cut the city’s CO2 emissions by two million tons per year.” (The calculations are described further in Applied Thermal Engineering.)
How does it work? The first step toward building such a system was gaining the ability to calculate just how much heat we’re talking about — that’s the breakthrough made by the Swiss scientists — which paves the way for “energy tunnels,” according to a release from EPFL. Such systems, low-cost and energy-efficient, would work similarly to a refrigerator, using plastic tubes with a liquid in them that could absorb the tunnels’ excess heat and move it to where it’s needed.
Top: Allen School graduate student Linxing Preston Jiang sets up Savannah Cassis, a UW undergraduate in psychology, as the first Sender. Above: Heather Wessel, a recent UW graduate with a bachelor’s degree in psychology, is a Sender for this experiment. She sees “Yes” and “No” on either side of the screen. Beneath the “Yes” option, an LED flashes 17 times per second. Beneath the “No” option, an LED flashes 15 times a second. Captions credit: University of Washington. Images credit: Mark Stone/University of Washington.
What is it? A research team at the University of Washington has brought telepathic communication one step closer to reality with a program called BrainNet, which they describe as “the first multi-person non-invasive direct brain-to-brain interface for collaborative problem solving.” As a demonstration, they had three people collaborate on playing a Tetris-like game, using only their minds to communicate.
Why does it matter? The researchers hope that brain-to-brain communication could lead to more fruitful interpersonal collaboration in general — for instance, by teams of folks working together to solve tough problems. But, warns Rajesh Rao, the corresponding author of a new paper in Nature, “this is just a baby step. Our equipment is still expensive and very bulky and the task is a game. We’re in the ‘Kitty Hawk’ days of brain interface technologies: We’re just getting off the ground.”
How does it work? Looking at the same Tetris-like computer game — but in different rooms, with no way to communicate — two people were designated “Senders” and one person was the “Receiver.” The Senders could see a block at the top of the screen, and a line it had to fit into at the bottom. The Receiver could see only the block, and had to rely on the Senders to explain how to move it. The Senders wore electroencephalography caps that picked up brain activity, and the Receiver wore a “wand” that stimulated neurons associated with visual signals: The Receiver would “see” bright flashes, dictated by the brain waves of the Sender, that indicated where and how to move the block. That’s the short version, anyway — read the whole play-by-play here.
A U-shaped nanowire pierces the membrane of a neuron. Caption and image courtesy of The Lieber Research Group.
What is it? Nine years ago, Harvard professor Charles M. Lieber developed the first nanotechnology devices that could record electrical activity inside a live cell. Now Lieber and colleagues have devised a way to “makes thousands of these devices at once, creating a nanoscale army that could speed efforts to find out what’s happening inside our cells,” according to the Harvard Gazette.
Why does it matter? Advanced technologies like the brain-to-brain interface described about, and brain-to-machine interfaces that could be developed to treat conditions like Parkinson’s, will require scientists to have a nano-level view of what’s going on inside our cells. As the Gazette puts it, the field previously faced a Goldilocks conundrum: Cellular recording devices that are too large will kill cells, while too-small devices pick up too much noise and not enough useful information. The approach Lieber developed in 2010 was able to pierce cell membranes and transmit accurate data without killing the cell, but to build that device was a painstaking process that took weeks.
How does it work? Lieber’s new nanowires, described in Nature Nanotechnology, are fabricated en masse to look like cooked spaghetti. (Very tiny spaghetti, anyway.) To separate the wires, Lieber and team pull them across a silicon surface carved with U-shaped trenches, which help untangle and capture the individual nanowires. So far, the new mass-produced transistors have been successfully used to record data from cardiac and neural cells.
Stanford engineers are testing a pair of smart glasses that can automatically focus on whatever you’re looking at. Caption credit: Stanford News. Image credit: Robert Konrad.
What is it? Engineers at Stanford have developed autofocals: basically, smart glasses that follow the movement of your eyes and focus wherever you’re looking.
Why does it matter? Most middle- and older-aged people experience visual impairment related to presbyopia, when the lens of the eye loses elasticity and focusing becomes more difficult — it’s typically treated by progressive lenses. But traditional progressive glasses require you to move your head toward whatever you’re looking at in order to focus your eyes; so if you’re trying to look in the side mirror while driving, for instance, that means turning your head away from the road. “More than a billion people have presbyopia and we’ve created a pair of autofocal lenses that might one day correct their vision far more effectively than traditional glasses,” said Gordon Wetzstein, a Stanford electrical engineer, and the co-author of a paper on autofocals in Science Advances.
How does it work? The autofocals rely on a mixture of technologies, not all of which were developed by the Stanford team; they developed the software that ties the whole thing together. Their prototype pairs fluid-filled lenses “that bulge and thin as the field of vision changes,” according to Stanford, with eye-tracking technology that registers where the wearer is looking and calculates the distance in between. The prototype is still a bit chunky; the next step will be to streamline it.
The team created tiny raised ringlets on their surface that act kind of like bowls, causing the droplets to splash upward rather than flow outward on the surface. GIF credit: Henri-Louis Girard, Dan Soto, and Kripa Varanas.
What is it? Engineers at MIT have designed a special surface that repels drops of water, helping the surface stay dry or avoid icing by sending droplets bouncing off.
Why does it matter? Let us count the ways, or better yet — let MIT, which sums up the potential of water-repellant tech in a news release: “keeping ice from building up on an airplane wing or a wind turbine blade, or preventing heat loss from a surface during rainfall, or preventing salt buildup on surfaces exposed to ocean spray.”
How does it work? As explained in a paper in ACS Nano, the researchers found that the key was not just getting water off a surface as quickly as possible — for instance, before it ices — but also to minimize the amount of area onto which a droplet of water can spread before bouncing off. To achieve both these aims, they created tiny raised ringlets on their surface that act kind of like bowls, causing the droplets to splash upward rather than flow outward on the surface. Mechanical engineering professor Kripa Varanasi said, “The idea of reducing contact area by forming ‘waterbowls’ has far greater effect on reducing the overall interaction than by reducing contact time alone.”