Stories tagged materials

May
22
2014

Scientists at University of California Berkeley have been able to use carbon nanotbues to create light activated "smart curtains" that respond automatically to light without batteries. The curtain material can bend or straighten in response to the flick of a light switch.

To create the smart curtain, carbon nanotubes are layered onto a plastic polycarbonate membrane. The carbon nanotubes absorb light, convert the light into heat, and then transfer the heat to the plastic membrane surface. The plastic responds to the heat by expanding, but the carbon nanotubes do not, causing the two-layered material to bend blocking the light.

To read more about this research visit:
https://newscenter.berkeley.edu/2014/01/09/smart-curtains/

Diagrams of Smart Curtains:
http://www.nature.com/ncomms/2014/140107/ncomms3983/fig_tab/ncomms3983_F...

Link to Smart Curtains YouTube video:

See video

To learn more about nanotechnology, science, and engineering, visit:
www.whatisnano.org

To see other nano stories on Science Buzz tagged #nano visit:
http://www.sciencebuzz.org/buzz_tags/nano

Growing nanowires horizontally yields "Nano-LEDs

Nano light emitters: Single row of nanowires (cylinders with red tops) with fin-shaped nanowalls extending outward (National Institute of Standards and Technology)
Nano light emitters: Single row of nanowires (cylinders with red tops) with fin-shaped nanowalls extending outward (National Institute of Standards and Technology)Courtesy NIST
These “nano-LEDs” may one day have their light-emission abilities put to work serving miniature devices such as nanogenerators or lab-on-a-chip systems. NIST.gov

In recent work published in ACS Nano,* Nikoobakht and Herzing increased the thickness of the gold catalyst nanoparticle from less than 8 nanometers to approximately 20 nanometers. The change resulted in nanowires that grew a secondary structure, a shark-like “dorsal fin” (referred to as a “nanowall”) where the zinc oxide portion is electron-rich and the gallium nitride portion is electron-poor. The interface between these two materials—known as a p-n heterojunction—allows electrons to flow across it when the nanowire-nanowall combination was charged with electricity. In turn, the movement of electrons produced light and led the researchers to dub it a “nano LED.”

Sep
19
2010

Materials science

Materials scientists figure out ways to make things stronger, cheaper, or better. A favorite technique is nano-self-assembly. Just mix together the right ingredients and "presto", you get a wonder material. Another great development would be for the material to be self-repairing.

Self healing solar cells

MIT scientist, Michael Strano, and his team have created a material made up of seven different compounds including carbon nanotubes, phospholipids, and proteins. Under the right conditions they spontaneously assemble themselves into a light-harvesting structure that produces an electric current. The assembly breaks apart when a surfactant (think soapy solution) is added but reassemble when it is removed. These new self-healing solar cells are already about double the efficiency of today’s best solar cells but could potentially be many times more efficient.

Learn more about self-healing solar cells

Sep
05
2010

Quest for the best optical display

Better resolution displays
Better resolution displaysCourtesy Yutaka Tsutano

I have been waiting for the new iPod Touch. I want a display screen so sharp, it looks like a photograph. The "retina display" creates an image out of pixels that are only 78 nanometers. How small is that? Well, more than 300 of these pixels are packed in each inch. Supposedly this is the limit for human perception, or as some fanboys might say, "It doesn't get any better than this!"

Plasmonic nanoresonators

University of Michigan researchers can do better, though, Their paper in Nature Communications titled, Plasmonic nanoresonators for high-resolution colour filtering and spectral imaging explains how pixels of only 10 microns can be produced.

Such pixel densities could make the technology useful in projection displays, as well as wearable, bendable or extremely compact displays, according to the researchers.

How does it work?

The resonators are kind of like a light filter. Two nano thin layers of metal selectively allow light to pass through small sets of slits. The slit spacing determines which wavelength of light makes it through the slits.

Red light emanates from slits set around 360 nanometers apart; green from those about 270 nanometers apart, and blue from those approximately 225 nanometers apart. The differently spaced gratings essentially catch different wavelengths of light and resonantly transmit through the stacks. LinuxForDevices.com

These displays are simpler, use fewer parts, are more efficient, and should be cheaper to make. I am not going to wait, though.

Sep
05
2010

Cotton for filters
Cotton for filtersCourtesy Martin Labar

Safe drinking water saves lives

Clean, safe drinking is desperately needed throughout the world. Usually filters "filter out" bacteria by having openings too small to get through. Trouble is, though, that the tiny holes get plugged up, stopping the flow of water. Stanford researchers have now developed a filter about 80,000 times faster than filters that trap bacteria.

Cheap and easy

The filter was made by dipping plain cotton cloth (from Walmart) in a mixture of silver nanowires and carbon nanotubes (for a few minutes). By charging the filter with 20 volts of electricity, over 98 percent of Escherichia coli bacteria were killed as they passed through. Even in remote or primitive areas, the electricity could be supplied by a small solar panel, or a couple 12-volt car batteries, or be generated from a stationary bicycle or by a hand-cranked device.

Cui said the next steps in the research are to try the filter on different types of bacteria and to run tests using several successive filters.
"With one filter, we can kill 98 percent of the bacteria," Cui said. "For drinking water, you don't want any live bacteria in the water, so we will have to use multiple filter stages."

Learn more
High-speed filter uses electrified nanostructures to purify water at low cost Stanford University News

Jul
25
2010

Graphene, the wonder material

Graphene: Unzip it and add oxygen to get graphene oxide
Graphene: Unzip it and add oxygen to get graphene oxideCourtesy Dr Thomas Szkopek
If you look at my posts about graphene you will understand why I think graphene is a super material. One chemically converted graphene product of interest (CCG) is graphene oxide (GO). Graphene oxide, an insulating version of graphene, is expected to be used for all kinds of material and electronic applications. Graphene oxide is also biodegradable. Bacteria from the genus Shewanella easily convert GO to harmless graphene.

Safer, more efficient way to make graphene oxide

A new paper in ACSNano from the lab of Rice chemist James Tour demonstrates an environmentally friendly way to make bulk quantities of graphene oxide (GO). Scientists have been making GO since the 19th century, but the new process eliminates the need for explosive or toxic ingredients.

The researchers suggested the water-soluble product could find use in polymers, ceramics and metals, as thin films for electronics, as drug-delivery devices and for hydrogen storage, as well as for oil and gas recovery. Science Dailey

Learn more about improved synthesis of graphene oxide

Graphene oxide gets green EurekaAlert

Feb
21
2010

Solar cells made from common materials

Solar cells for everyone
Solar cells for everyoneCourtesy Dominic

Solar cells produce less than 1/1000 of the Earth's electricity. This is mainly because they are expensive and are made from rare, hard to obtain materials.
An IBM research team, managed by David Mitzi, is working on photovoltaic cells that are made from common materials.

The new solar cells are also cheaper to manufacture, using a “printing” technique that uses a hydrazine solution containing copper and tin with nanoparticles of zinc dispersed within it. The solution is then spin-coated and heat treated in the presence of selenium or sulfur vapor. PhysOrg

9.6% Efficiency

This new material, called kesterite, was 6.8% efficient in 2009. IBM increased the efficiency to 9.8% and is planning to increase the efficiency above 11 per cent, which is equal to or better than the traditional solar cells.

Abstract of published paper: High-Efficiency Solar Cell with Earth-Abundant Liquid-Processed Absorber Advanced Materials

U.S. Ski Team members Julia Mancuso, Ted Ligety and Scott Macartney, and Katharine Flores, an associate professor in the Department of Materials Science and Engineering at Ohio State University, explain how the materials used to make skis play a vital role in their performance on the mountain.

Feb
06
2010

Liquid Glass
Liquid GlassCourtesy Hustvedt
Soon almost every product you purchase will be coated with liquid glass. It repels bacteria, water and dirt, is highly flexible and breathable, and is easy to clean using only water or a simple wipe with a damp cloth.
Nanopool, who makes "Liquid Glass" says it is available in Germany now, and will be in the UK early in 2010.

Quantum force bonding

Using their secret process, NanoPool extracts silicon dioxide molecules from glass and mixes them with water or ethanol. When sprayed on various materials, a 100 nanometer coating offers protection against bacteria, graffiti, stains and is food safe and environmentally friendly.

Source:
Spray-on liquid glass is about to revolutionize almost everything PhysOrg.com

Feb
06
2010

Graphene
GrapheneCourtesy Carbophiliac

Graphene is great

Graphene is a single atom thick layer of carbon atoms in a honeycomb like arrangement (read more about graphene here in ScienceBuzz.org)

Graphene transistors are the fastest

Transistors are like valves that can turn the flow of electricity off and on. Computers can use transistors and logic circuits to solve all kinds of problems. These problems can be solved faster if the transistors can turn on and off faster. Transistors made out of graphene now can switch on and off 100 billion times per second (100 GigaHertz). State-of-the-art silicon transistors of the same gate length have a switching frequency of about 40 GigaHertz.

IBM develops next-generation transistors

IBM just announced their breakthrough in the magazine Science.

Uniform and high-quality graphene wafers were synthesized by thermal decomposition of a silicon carbide (SiC) substrate. The graphene transistor itself utilized a metal top-gate architecture and a novel gate insulator stack involving a polymer and a high dielectric constant oxide. The gate length was modest, 240 nanometers, leaving plenty of space for further optimization of its performance by scaling down the gate length. ScienceDaily