Home > Press > 'Perfect black' coating can render a 3D object flat, raises intriguing dark veil possibility in astronomy
Abstract:
A carbon nanotube coating developed at the University of Michigan acts as a "magic black cloth" that conceals an object's three-dimensional geometry and makes it look like a flat black sheet.
Written by Nicole Casal Moore
The 70-micron coating, or carbon nanotube carpet, is about half the thickness of a sheet of paper. It absorbs 99.9 percent of the light that hits it, researchers say.
"You could use it to completely hide any 3D attributes of an object," said Jay Guo, a professor in the Department of Electrical Engineering and Computer Science and principal investigator.
"It's not cloaking, as the object can still cast a shadow. But if you put an object on a black background, then with this coating, it could really become invisible."
A paper on the research is newly published online in Applied Physics Letters.
To demonstrate this concept, the researchers made a raised, microscopic tank shape on a piece of silicon. They then grew the carbon nanotube carpet on top of the entire silicon chip. In photos taken through an optical microscope, they show that the tank is imperceptible. As a control, they did this again, carving out a rectangle that was not coated with carbon nanotubes. The rectangle is visible on this chip, but the tank remains hidden.
Here's how the new coating works: Human eyes perceive an object based on how it reflects or scatters light. The "refractive index" of this new coating is similar to that of air, meaning light traveling through air doesn't scatter or reflect when it hits the coating.
It's well known that carbon nanotubes are capable of absorbing light, but the researchers were able to push it to such a high percentage by spacing them just right.
The "perfect black" material Guo's team created for this coating has a host of varied applications. It could possibly be used in display screens for ultra-high contrast and a crisper picture. It holds promise as solar heating device. The National Institute of Standards and Technology is using a similar material to absorb infrared light and measure the amount of heat it can generate.
The coating could inspire a new type of camouflaging paint for stealth aircraft. Today's stealth planes use shape to scatter electromagnetic waves and avoid detection, and this scheme could actually absorb the waves.
"The carbon nanotube forest can absorb very wide range of electromagnetic wave from ultraviolet up to terahertz," Guo said, "and in principle it can be applied to an arbitrary sized object."
Just how large an object? Guo suggested an intriguing possibility—perhaps entire planets or even stars.
"Since deep space itself is a perfect dark background, if a planet or star were surrounded by a thick, sooty atmosphere of light-absorbing carbon nanomaterial gases, it would become invisible due to the same principle," Guo said. "It would become totally dark to our instruments that rely on the detection of electromagnetic waves. Could this explain some of the missing matter in the universe?"
X-rays or gamma rays would be able to penetrate through the hypothetical "dark veil" Guo proposes. Or, objects behind such veils would cast a shadow by distant stars behind them.
The paper is called "Low density carbon nanotube forest as an index-matched and near perfect absorption coating." Other co-authors are electrical engineering post-doc Haofei Shi and Ph.D. student Hyoung Won Baac and mechanical engineering Ph.D. student Jong Ok. The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.
####
About University of Michigan
The University of Michigan College of Engineering is ranked among the top engineering schools in the country. At $180 million annually, its engineering research budget is one of the largest of any public university. Michigan Engineering is home to 11 academic departments, numerous research centers and expansive entrepreneurial programs. The college plays a leading role in the Michigan Memorial Phoenix Energy Institute and hosts the world-class Lurie Nanofabrication Facility. Michigan Engineering's premier scholarship, international scale and multidisciplinary scope combine to create The Michigan Difference.
For more information, please click here
Contacts:
University of Michigan
News Service
412 Maynard St.
Ann Arbor, MI 48109-1399
Phone: (734) 764 7260
Fax: (734) 764 7084
Copyright © University of Michigan
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
Related News Press |
News and information
Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024
NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Discoveries
Chemical reactions can scramble quantum information as well as black holes April 5th, 2024
New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024
Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024
Materials/Metamaterials/Magnetoresistance
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024
Announcements
NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Aerospace/Space
Under pressure - space exploration in our time: Advancing space exploration through diverse collaborations and ethical policies February 16th, 2024
Bridging light and electrons January 12th, 2024
Manufacturing advances bring material back in vogue January 20th, 2023
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||