Subscribe free to our newsletters via your
. 24/7 Space News .




ENERGY TECH
Researchers build atomically thin gas and chemical sensors
by Staff Writers
Riverside CA (SPX) Feb 20, 2015


This is a schematic of the molybdenum disulfide (MoS2) thin-film sensor with the deposited molecules that create additional charge. Image courtesy UC Riverside. For a larger version of this image please go here.

The relatively recent discovery of graphene, a two-dimensional layered material with unusual and attractive electronic, optical and thermal properties, led scientists to search for other atomically thin materials with unique properties.

Molybdenum disulfide (MoS2) has proved to be one of the most promising. Single-layer and few-layer molybdenum disulfide devices have been proposed for electronic, optoelectronic and energy applications. A team of researchers, led by engineers at the University of California, Riverside's Bourns College of Engineering, have developed another potential application: sensors.

"The sensors are everywhere now, including in smart phones and other portable electronic devices," said Alexander Balandin, UC Presidential Chair and professor of electrical and computer engineering at UC Riverside, who is the lead author of the paper.

"The sensors we developed are small, thin, highly sensitive and selective, making them potentially ideal for many applications."

Balandin and the graduate students in his lab built the atomically thin gas and chemical vapor sensors from molybdenum disulfide and tested them in collaboration with researchers at the Rensselaer Polytechnic Institute in Troy, N.Y. The devices have two-dimensional channels, which are great for sensor applications because of the high surface-to-volume ratio and widely tunable concentration of electrons.

The researchers demonstrated that the sensors, which they call molybdenum disulfide thin-film field-effect transistors (TF-FET), can selectively detect ethanol, acetonitrile, toluene, chloroform and methanol vapors.

The findings were published in a recent paper, "Selective chemical vapor sensing with few-layer MoS2 thin-film transistors: Comparison with graphene devices," in the journal Applied Physics Letters. In addition to Balandin, co-authors were Rameez Samnakay and Chenglong Jiang, both Ph.D. students in Balandin's lab, and Michael Shur and Sergey Rumyantsev, both of Rensselaer Polytechnic Institute.

The selective detection did not require prior functionalization of the surface to specific vapors. The tests were conducted with the as fabricated devices and intentionally aged devices. The molybdenum disulfide sensors used in the study were aged for two months because practical applications require that sensors remain stable and operational for at least a month.

Sensors made with atomically thin layers of MoS2 revealed better selectivity to certain gases owing to the electron energy band gap in this material, which resulted in strong suppression of electrical current upon exposure to some of the gases. Graphene devices, from the other side, demonstrated selectivity when one used current fluctuations as a sensing parameter.

"Sensors implemented with atomically thin MoS2 layers are complementary to graphene devices, which is good news," Balandin said. "Graphene has very high electron mobility while MoS2 has the energy band gap."

The uniqueness of the UC Riverside built atomically thin gas sensors - both graphene and MoS2 - is in the use of the low-frequency current fluctuations as additional sensing signal. Conventionally such chemical sensors use only the change in the electrical current through the device or a change in the resistance of the device active channel.

In a separate paper, the same researchers demonstrated high temperature operation of the molybdenum disulfide atomically thin film transistors. The work was described in a paper, "High-temperature performance of MoS2 thin-film transistors: Direct current and pulse current-voltage characteristics," that was just published in the Journal of Applied Physics.

Many electronic components for control systems and sensors are required to operate at temperature above 200 degrees Celsius. Examples of the high temperature applications include turbine engine control in aerospace and energy generation and oil field instruments.

The availability of transistors and circuits to operate at temperatures above 200 degrees Celsius is limited. Devices made of silicon carbide and gallium nitride - conventional semiconductors - hold promise for extended high-temperature operation but are still not cost-effective for high volume applications. There is a need for new material systems that can be used to make field-effect transistors sensors that work at high temperatures.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of California - Riverside
Powering The World in the 21st Century at Energy-Daily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





ENERGY TECH
Researcher first to observe 'god particle' analogue in superconductors
Ramat Gan, Israel (SPX) Feb 20, 2015
The Nobel Prize-winning discovery of the Higgs boson - the "God particle" believed responsible for all the mass in the universe - took place in 2012 at CERN's Large Hadron Collider, an underground facility where accelerated sub-atomic particles zip around the circumference of a 27-kilometer (16.9-mile) ring-shaped tunnel. But what goes around comes around: more than 50 years ago, the first hint ... read more


ENERGY TECH
Application of laser microprobe technology to Apollo samples refines lunar impact history

NASA releases video of the far side of the Moon

US Issuing Licenses for Mineral Mining on Moon

LRO finds lunar hydrogen more abundant on Moon's pole-facing slopes

ENERGY TECH
Scientists fail to explain strange plumes spotted on Martian surface

NASA's Curiosity Analyzing Sample of Martian Mountain

Mars Rover Nearing Marathon Achievement

NASA's Curiosity Analyzing Sample of Martian Mountain

ENERGY TECH
London workshop teaches nuts and bolts behind tech

Critical NASA Science Returns to Earth aboard SpaceX Dragon Spacecraft

45th Space Wing, SpaceX sign first-ever landing pad agreement at the Cape

Russian research team explores vision complications for astronauts

ENERGY TECH
More Astronauts for China

China launches the FY-2 08 meteorological satellite successfully

China's Long March puts satellite in orbit on 200th launch

Countdown to China's new space programs begins

ENERGY TECH
Europe destroys last space truck to ISS

NASA, Space Station Partners Announce Future Mission Crew Members

Camera to record doomed ATV's disintegration - from inside

ATV to bid farewell to Space Station for last time

ENERGY TECH
Soyuz Installed at Baikonur, Expected to Launch Wednesday

SpaceX launches deep-space weather observatory

SpaceX cargo craft returns to Earth

High seas force SpaceX to ditch bid to recycle rocket

ENERGY TECH
Scientists predict earth-like planets around most stars

"Vulcan Planets" - Inside-Out Formation of Super-Earths

Dawn ahead!

Habitable Evaporated Cores

ENERGY TECH
3-D printing with custom molecules creates low-cost mechanical sensor

See here now: Telescopic contact lenses and wink-control glasses

Getting in shape

Google, Mattel bring virtual reality to iconic toy




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.