Chemist Inventor 'Sniffs' His Way to Prestigious US$500,000 Lemelson-MIT Prize

Dr. Timothy M. Swager has a nose for explosives. The Massachusetts Institute of Technology Professor of Chemistry claims he can “almost always take a whiff of a chemical and make a pretty good guess as to what class a volatile compound might be in.” But Swager’s nose is nothing compared to the amplified chemical sensors he invented to detect vapors of common bomb-making chemicals, such as TNT. For his entire body of inventive work, the Lemelson-MIT Program named Swager the 2007 winner of the $500,000 Lemelson-MIT Prize, the most-prestigious cash prize for invention in the United States. This year, the prize criteria were modified to specify the winner be a mid-career inventor who is rising in his or her field.

“The originality, practicality and timeliness of Dr. Swager’s inventions made him a stand-out candidate for this year’s US$500,000 Lemelson-MIT Prize,” said Merton Flemings, director of the Lemelson-MIT Program, which has given the award to an accomplished inventor for the past 12 years. “For instance, soldiers and Marines in Iraq are already benefiting from his explosive-detection inventions, and his molecular wire inventions will likely find application in a wide range of healthcare, environmental and security areas.”

An Amplified Response

Among his many inventions, Swager and his colleagues invented amplifying fluorescent polymers that can attract nitro aromatic molecules, a class of chemicals typically used in explosives. In most molecular sensors, the strength of the emitted signal is proportional to the number of target molecules reaching the sensor. Therefore, they are usually not sensitive enough to detect very small trace amounts of the target substance.

Swager reasoned that if he designed a polymer chain that would carry a signal except when a single target molecule struck the chain, he would have an extraordinarily sensitive detector. Thus, if the target molecule were TNT, a bomb detection device could be constructed from the polymer.

“Imagine a string of holiday lights,” Swager explained. “If I break one bulb, then that strand goes down. Moreover, imagine if I wire a bunch of strands together. If I break a single bulb in any one of them, then that brings the whole thing down. That broken bulb represents the TNT molecule or vapor you’re trying to find. The interruption tells you something’s there.”

The TNT molecules can bind anywhere along the polymer chain. “It’s random where the TNT will bind,” Swager said, “so you give it as many opportunities to bind as it can possibly want.”

The ‘Dog’s Nose’ Knows

In 2001, Swager licensed his patented polymer technology to Nomadics, now a unit of ICx Technologies, for use in that company’s Fido Explosives Detector, so named for its ability to simulate a bomb-sniffing dog.

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