Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Drawing a line, with carbon nanotubes

10.10.2012
New low-cost, durable carbon nanotube sensors can be etched with mechanical pencils.

Carbon nanotubes offer a powerful new way to detect harmful gases in the environment. However, the methods typically used to build carbon nanotube sensors are hazardous and not suited for large-scale production.

A new fabrication method created by MIT chemists — as simple as drawing a line on a sheet of paper — may overcome that obstacle. MIT postdoc Katherine Mirica has designed a new type of pencil lead in which graphite is replaced with a compressed powder of carbon nanotubes. The lead, which can be used with a regular mechanical pencil, can inscribe sensors on any paper surface.

The sensor, described in the journal Angewandte Chemie, detects minute amounts of ammonia gas, an industrial hazard. Timothy Swager, the John D. MacArthur Professor of Chemistry and leader of the research team, says the sensors could be adapted to detect nearly any type of gas.

“The beauty of this is we can start doing all sorts of chemically specific functionalized materials,” Swager says. “We think we can make sensors for almost anything that’s volatile.”

Other authors of the paper are graduate student Jonathan Weis and postdocs Jan Schnorr and Birgit Esser.

Pencil it in

Carbon nanotubes are sheets of carbon atoms rolled into cylinders that allow electrons to flow without hindrance. Such materials have been shown to be effective sensors for many gases, which bind to the nanotubes and impede electron flow. However, creating these sensors requires dissolving nanotubes in a solvent such as dichlorobenzene, using a process that can be hazardous and unreliable.

Swager and Mirica set out to create a solvent-free fabrication method based on paper. Inspired by pencils on her desk, Mirica had the idea to compress carbon nanotubes into a graphite-like material that could substitute for pencil lead.

To create sensors using their pencil, the researchers draw a line of carbon nanotubes on a sheet of paper imprinted with small electrodes made of gold. They then apply an electrical current and measure the current as it flows through the carbon nanotube strip, which acts as a resistor. If the current is altered, it means gas has bound to the carbon nanotubes.

The researchers tested their device on several different types of paper, and found that the best response came with sensors drawn on smoother papers. They also found that the sensors give consistent results even when the marks aren’t uniform.

Two major advantages of the technique are that it is inexpensive and the “pencil lead” is extremely stable, Swager says. “You can’t imagine a more stable formulation. The molecules are immobilized,” he says.

The new sensor could prove useful for a variety of applications, says Zhenan Bao, an associate professor of chemical engineering at Stanford University. “I can already think of many ways this technique can be extended to build carbon nanotube devices,” says Bao, who was not part of the research team. “Compared to other typical techniques, such as spin coating, dip coating or inkjet printing, I am impressed with the good reproducibility of sensing response they were able to get.”

Sensors for any gas

In this study, the researchers focused on pure carbon nanotubes, but they are now working on tailoring the sensors to detect a wide range of gases. Selectivity can be altered by adding metal atoms to the nanotube walls, or by wrapping polymers or other materials around the tubes.

One gas the researchers are particularly interested in is ethylene, which would be useful for monitoring the ripeness of fruit as it is shipped and stored. The team is also pursuing sensors for sulfur compounds, which might prove helpful for detecting natural gas leaks.

The research was funded by the Army Research Office through MIT’s Institute for Soldier Nanotechnologies and a National Institutes of Health fellowship to Mirica.

Caroline McCall | EurekAlert!
Further information:
http://www.mit.edu
http://web.mit.edu/newsoffice/2012/drawing-with-a-carbon-nanotube-pencil-1009.html

More articles from Life Sciences:

nachricht Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>