We've seen how easily carbon nanotubes can detect harmful gases. What's not so easy is building the sensors. Methods are often hazardous and unfit for large-scale production.
However, some chemists from the Massachusetts Institute of Technology (MIT) have come up with a new fabrication method — one that's as easy as drawing a line on a piece of paper.
Katherine Mirica, an MIT postdoc, designed a new type of lead that can be used in an ordinary mechanical pencil, where graphite is replaced with a compressed powder of carbon nanotubes. With a few clicks from a thumb, sensors can be drawn on any paper surface.
To create their sensors, researchers drew a line of carbon nanotubes on a
piece of paper stamped with small, gold electrodes. Next, they ran an
electrical current through the carbon nanotube, which acts as a
resistor. If the current is altered, that indicates a gas has bound to
the carbon nanotubes.
The sensor detects trace amounts of ammonia gas, an industrial hazard and key ingredient in explosives. And the devices can be revamped to to detect almost any type of gas, says Timothy Swager, the John D. MacArthur Professor of Chemistry, who led the project.
"The beauty of this is we can start doing all sorts of chemically
specific functionalized materials,” Swager said in a university news release. "We think we can make
sensors for almost anything that's volatile."
Researchers said the two most significant advantages of the method are that it's inexpensive and the "pencil lead" is exceptionally stable. The team published their findings in the journal Angewandte Chemie.
Credit: Jan Schnorr