Graphene from gases for new, bendable electronics.
Flexible, translucent and ultrathin, layers of carbon atoms called graphene are also excellent electrical conductors that could find use in flexible computer displays, molecular electronics and new wireless communications. Making high-quality graphene sheets is usually a slow, painstaking process, but now several research groups have discovered ways to make patterned graphene circuits using techniques borrowed from microchip manufacturing, which can be scaled up for mass production.
Layers of graphene — carbon atoms arranged in a chicken-wire pattern one atom thick — can be manually peeled away from the graphite in pencils using adhesive tape. In contrast, the new technique causes carbon atoms in a vapor of hydrocarbons to settle onto a nickel surface and arrange into graphene’s characteristic pattern of hexagons.
Using standard chip-making techniques, circuit designs are etched into the nickel surface. As the graphene layers form, they take on the shape of the circuit template, researchers report in the Jan. 15 Nature.
“Finding a suitable material that’s transparent yet conducting and thin is a big deal,” says Philip Kim, coauthor of the study and a condensed matter physicist at Columbia University. Kim and his colleagues showed that the vapor-deposited graphene retains the excellent electrical properties of manually peeled graphene, even when bent on a flexible surface
Graphene-based nitrogen dioxide gas sensors.
graphene could selectively absorb/desorb NOx molecules at room temperature. Chemical doping with NO2 molecules changed the conductivity of the graphene layers, which was quantified by monitoring the current–voltage characteristics at various NO2 gas concentrations. The adsorption rate was found to be more rapid than the desorption rate, which can be attributed to the reaction occurred on the surface of the graphene layer. The sensitivity was 9% when an ambient of 100 ppm NO2 was used. Graphene-based gas sensors showed fast response, good reversibility, selectivity and high sensitivity. Optimization of the sensor design and integration with UV-LEDs and Silicon microelectronics will open the door for the development of nano-sized gas sensors that are extremely sensitive.
. 2. The current–voltage characteristics under N2 and NO2 gas ambients at room temperature.
3. The time response and decay of graphene-based gas sensors when a NO2 ambient (1% concentration) was used.
A new study from Rensselaer Polytechnic Institute demonstrates how graphene foam can outperform leading commercial gas sensors in detecting potentially dangerous and explosive chemicals. The discovery opens the door for a new generation of gas sensors to be used by bomb squads, law enforcement officials, defense organizations, and in various industrial settings.
The new sensor successfully and repeatedly measured ammonia (NH3) and nitrogen dioxide (NO2) at concentrations as small as 20 parts-per-million. Made from continuous graphene nanosheets that grow into a foam-like structure about the size of a postage stamp and thickness of felt, the sensor is flexible, rugged, and finally overcomes the shortcomings that have prevented nanostructure-based gas detectors from reaching the marketplace
Flexible, translucent and ultrathin, layers of carbon atoms called graphene are also excellent electrical conductors that could find use in flexible computer displays, molecular electronics and new wireless communications. Making high-quality graphene sheets is usually a slow, painstaking process, but now several research groups have discovered ways to make patterned graphene circuits using techniques borrowed from microchip manufacturing, which can be scaled up for mass production.
Layers of graphene — carbon atoms arranged in a chicken-wire pattern one atom thick — can be manually peeled away from the graphite in pencils using adhesive tape. In contrast, the new technique causes carbon atoms in a vapor of hydrocarbons to settle onto a nickel surface and arrange into graphene’s characteristic pattern of hexagons.
Using standard chip-making techniques, circuit designs are etched into the nickel surface. As the graphene layers form, they take on the shape of the circuit template, researchers report in the Jan. 15 Nature.
“Finding a suitable material that’s transparent yet conducting and thin is a big deal,” says Philip Kim, coauthor of the study and a condensed matter physicist at Columbia University. Kim and his colleagues showed that the vapor-deposited graphene retains the excellent electrical properties of manually peeled graphene, even when bent on a flexible surface
Graphene-based nitrogen dioxide gas sensors.
graphene could selectively absorb/desorb NOx molecules at room temperature. Chemical doping with NO2 molecules changed the conductivity of the graphene layers, which was quantified by monitoring the current–voltage characteristics at various NO2 gas concentrations. The adsorption rate was found to be more rapid than the desorption rate, which can be attributed to the reaction occurred on the surface of the graphene layer. The sensitivity was 9% when an ambient of 100 ppm NO2 was used. Graphene-based gas sensors showed fast response, good reversibility, selectivity and high sensitivity. Optimization of the sensor design and integration with UV-LEDs and Silicon microelectronics will open the door for the development of nano-sized gas sensors that are extremely sensitive.
. 2. The current–voltage characteristics under N2 and NO2 gas ambients at room temperature.
3. The time response and decay of graphene-based gas sensors when a NO2 ambient (1% concentration) was used.
A new study from Rensselaer Polytechnic Institute demonstrates how graphene foam can outperform leading commercial gas sensors in detecting potentially dangerous and explosive chemicals. The discovery opens the door for a new generation of gas sensors to be used by bomb squads, law enforcement officials, defense organizations, and in various industrial settings.
The new sensor successfully and repeatedly measured ammonia (NH3) and nitrogen dioxide (NO2) at concentrations as small as 20 parts-per-million. Made from continuous graphene nanosheets that grow into a foam-like structure about the size of a postage stamp and thickness of felt, the sensor is flexible, rugged, and finally overcomes the shortcomings that have prevented nanostructure-based gas detectors from reaching the marketplace
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