In an effort to build an affordable system for detecting chemical warfare agents and industrial pollutants in the environment, a couple of scientists at MIT have miniaturized gas chromatography and mass spectrometry techniques into what they hope will eventually result in a matchbook-size detector.
Their detector uses gas chromatography and mass spectrometry (GC-MS) to identify gas molecules by their telltale electronic signatures. Current versions of portable GC-MS machines, which take about 15 minutes to produce results, are around 40,000 cubic centimeters, about the size of a full paper grocery bag, and use 10,000 joules of energy.
The new, smaller version consumes about four joules and produces results in about four seconds.
The device, which the researchers plan to have completed within two years, could be used to help protect water supplies or for medical diagnostics, as well as to detect hazardous gases in the air.
The analyzer works by breaking gas molecules into ionized fragments, which can be detected by their specific charge (ratio of charge to molecular weight).
Gas molecules are broken apart either by stripping electrons off the molecules, or by bombarding them with electrons stripped from carbon nanotubes. The fragments 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.
Shrinking the device greatly reduces the energy needed to power it, in part because much of the energy is dedicated to creating a vacuum in the chamber where the electric field is located.
Another advantage of the small size is that smaller systems can be precisely built using microfabrication. Also, batch-fabrication will allow the detectors to be produced inexpensively.
We envision the technology will one day find its way into an iPod as a feature to check what pesticides were sprayed on your dinner salad.
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