Sensor could quickly detect hazardous chemicals

Engineers Edge (January 21, 2008) - MIT engineers are developing a very small sensor that may be used to detect minor quantities of hazardous or toxic chemicals and gases quicker than current senor devices.

The engineering researchers shrunk common techniques of gas chromatography and mass spectrometry to devices that are the size of a typical computer mouse. Professor Akintunde Ibitayo Akinwande leads the team at MIT and plans to build a sensor approximately the size of a common matchbox.
"Everything we're doing has been done on a macro scale. We are just scaling it down," said Akinwande, a professor of electrical engineering and computer science and member of MIT's Microsystems Technology Laboratories (MTL).

Scaling down miniature gas sensors are much easier to integrate into an industrial or scientific application. The Small sensor devices require less power to perform and improves their sensitivity to trace amounts of gases, Akinwande said.
Professor Akintunde Ibitayo Akinwande is leading an international team that includes scientists from the University of Cambridge, the University of Texas at Dallas, Clean Earth Technology and Raytheon, as well as MIT.

Their sensor design utilizes gas chromatography and mass spectrometry GC-MS (Gas chromatography "GC" and mass spectrometry "MS") techniques to measure or detect gas molecules by their specific electronic signatures. Current industrial GC-MS technologies are about the size of a full paper grocery bag, and use approximately 10,000 joules of energy and take about 15 minutes to produce readings. The system under development will be smaller, consume approximately four joules of energy and produces readings less than five seconds.

The sensor technology is scheduled for completion within two years, could be used to monitor water supplies, perform medical diagnostics, and detect hazardous gases in the air.

The sensor performs by breaking gas molecules into ions that are measured or detected by the charge (ratio of charge to molecular weight). The gas molecules are broken into ions by bombarding them with electrons stripped from carbon nanotubes, which removes the electrons from the gas molecules. These gas elements are then sent through a long, narrow electric field. At the end of the field, the ions' charges are converted to voltage and measured by an electrometer, yielding the molecules' distinctive electronic signature.

The research and development started three years ago and is funded by the Defense Advanced Research Projects Agency and the U.S. Army Soldier Systems Center in Natick, Mass.
Adapted from materials provided by Massachusetts Institute of Technology.