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Like Aladdin's magical flying carpet in The Arabian Nights, University of Pennsylvania researchers have defied logic and created a system that allowed them to levitate a pair of small plastic trays by harnessing the power of light.
While this minor miracle seems like something out of a far-out sci-fi flick, their methods, based on a new light-induced flow technology, could have a number of real world applications, including lifting silicon chip climate sensors into the upper atmosphere and aiding NASA in their future exploration of the Red Planet.
Employing energy generated from intense LEDs set up in an acrylic vacuum chamber, UPenn doctoral candidate Mohsen Azadi and his lab team enabled two tiny Mylar plates to hover by themselves in a controlled environment. Whoa!
Demonstrations of light-induced flow, AKA photophoresis, aren't completely new, scientists had so far only been able to levitate invisible aerosols and sort particles in microfluidic devices. This breakthrough represents the first time researchers around the world have actually floated an object large enough to wrap your fingers around.
“We didn't know what we were expecting to see,” Azadi told Wired. “But we hoped to see something. When the two samples lifted, there was this gasp between all four of us.”
As detailed in a new study published in the online journal Science Advances, these simple Mylar wedges, each measuring approximately 6mm wide and an incredible 500 nanometers thin, hovered in mid-air relying only on light waves glaring from below. To achieve this astonishing feat, the bank of LEDs warms the Mylar’s specially-coated underbelly, energizing the air particles beneath the plastic and pushing the plates in the opposite direction with a gentle optical wind.
The Mylar disks chosen for the experiment were 50 times thinner than normal household plastic wrap, and is actually transparent. Their team layered the Mylar surface with atomic-scale, rod-shaped carbon threads the breadth of a human hair called carbon nanotubes.
As this black carbon carpet absorbs light, its jumble of tiny nanotubes warms up. Gas molecules sliding into the microscopic jungle heat up more than molecules bouncing off the smooth upper surface. This torrent of heated molecules blasting down from the underneath surface faster than those rising from the top creates a unique dynamic lift force.
Far from the invention of an actual flying carpet imagined in fairy tales, NASA's scientific minds are already marinating over how this tech can assist missions into the mesosphere, a lofty, neglected region of Earth's atmosphere (31 to 53 miles high) that’s tough to conduct research in and often overlooked by climatologists.
“Sometimes it’s called ignorosphere, in joke,” Igor Bargatin, a mechanical engineering professor at UPenn and lead study author, explained to Wired. “We just don’t have access to it. You can send a rocket for a few minutes at a time, but that’s very different from doing measurements using airplanes or balloons.”
Our mesosphere is fertile territory for a multitude of intriguing weather phenomena, such as odd blue and red lightning and microscopic meteors zooming through the region on a daily basis. Additionally, compounds in the mesosphere are invaluable for scientists monitoring dangerous ozone damage.
“Solar storms cause energetic particles to enter the mesosphere, creating nitric oxide,” notes Daniel Marsh, an atmospheric scientist at the National Center for Atmospheric Research.
Bargatin, Azadi, and the entire crew now intend to develop a miniature flight system that can hoist mini sensors into the mesosphere using this light-powered levitator technology. NASA can greatly benefit from their discoveries as well, directing devices toward its Mars research due to the fact that pressure in the planet's atmosphere is very similar to Earth’s mesosphere.
“You can just take off once per day, and go up and then come back down and land on your little Martian lander,” added Paul Newman, chief scientist of Earth Sciences at NASA’s Goddard Space Flight Center. “We don’t have that information on Mars. That would be fantastic.”