Screening pollutants

Research sponsored by the National Science Foundation and DARPA Research Center for Micro/Nano-Electromechanical Transducers has garnered some breakthroughs in what could be the next era of pollution reduction.

Graphene membranes, which are known to be selectively porous, exhibit the capability to screen out pollutants by separating inert carbon dioxide molecules from larger, more potentially harmful ones, such as nitrogen and sulphur hexaflouride.   The graphene membranes work especially well for gaseous "pollutant" materials because of the semi-permeable nature of graphene membranes.

Illustration by Zhangmin Huang

"The findings are a significant step toward the realization of more energy-efficient membranes for natural gas production and for reducing carbon dioxide emissions from power plant exhaust pipes," reports the University of Colorado at Boulder, where much of the research took place.  "Those characteristics make graphene an ideal material for creating a separation membrane because it is durable and yet doesn’t require a lot of energy to push molecules through it, he said."

Given these findings, may I hypothesize about some other related applications --  Radiation containment?   Automobile exhaust pipes?  Chimney screens?

As with any recent breakthrough, there are some logistical challenges to be overcome before the applications can be widely applied.    For example, "creating large enough sheets of graphene to perform separations on an industrial scale, and developing a process for producing precisely defined nanopores of the required sizes are areas that need further development. The CU-Boulder experiments were done on a relatively small scale."

Extending memory beyond Moore's Law

Red Orbit is reporting that researchers at Rice University have been able to combine the almost ionic properties of graphene with the light-penetrable properties of silicone oxide to design what amounts to flexible and transparent 3D, two-terminal memories. 

"[The] highly transparent, nonvolatile resistive memory devices are based on the revelation that silicon oxide can be a switch  At just 5 nanometers, a channel can be created to extend memory beyond Moore’s Law, which predicts computer circuitry will double in power every two years.

Manufacturers are finding physical limits on current architectures when trying to fit millions of bits on small devices. Currently, electronics are made with 22 nanometer circuits.

Combining silicon and graphene enables the scientists to extend the possibilities of where memory can be placed. The devices could not only have potential for facing the harsh conditions of radiation, but also could be able to withstand heat of up to about 1,300 degrees Fahrenheit.

source:  http://www.redorbit.com/news/technology/1112706299/graphene-flexible-transparent-memory-100312/?print=true

Stepping down from 22 to 5 nanometers may not seem like a huge leap, but thus far it has presented some logistical challenges.  Up to this point, the primary limitation in down-sizing circuitry has been in finding materials that can retain their "transmission" properties at such small diameters.  As explained by Dr. James Tour, "We need transparent wires to wire them together and bring in the needed voltages and record the currents."

So what is it that makes graphene so special?  

"Graphene, being transparent, is being used as the wiring for both the input and output electrodes on the plastic substrates." he explains further.  "On the glass substrates, we use indium-tin-oxide (ITO), a transparent metallic electrode for the input and graphene on top for the output.”