PORTLAND, Ore. Purdue University researchers have demonstrated a portable instrument that they claim can identify any substance in less than a second, much like the "tricorders" used by the crew of the Enterprise in the Star Trek series.
The 20-pound, battery-powered unit combines a mass spectrometer with a desorption electrospray ionization (DESI) source.
"The detection is done in an ion trapan RF device that traps ions, then lets them out on the basis of their masses, enabling you to be exactly sure what compound you are sensing," said Graham Cooks, Henry Bohn Hass distinguished professor of analytical chemistry at Purdue's College of Science.
Cooks' team previously reported on a larger, laboratory version that runs off line current. Prosolia Inc. (Indianapolis) has commercialized the larger version of the Purdue-developed DESI source, and Griffin Analytical Technologies LLC, (West Lafayette, Ind.) has commercialized the full-size version of the ion-trap mass spectrometer. Both target scientific labs.
"Now that we have demonstrated it's possible to miniaturize both devices into a single handheld unit, we expect that the two companies will together come out with a commercial version of a tricorder," said Cooks.
The larger version of the mass spectrometer weighs 20 pounds alone. The portable version contributes only 8 pounds to the final weight of the portable unit. "The 20-pound [combined] device, whose weight includes the batteries, has a full Windows-based computer control system and enough hard-disk storage to keep the patterns of all the compounds you want to test for, so that the portable unit could be used by first responders to instantly identify the substances in, say, a toxic spill," Cooks said.
He estimates that mass production of the device could reduce its end-user cost to around $2,000, making it affordable for everything from airport security to medical scans and food testing.
The mass spectrometers used today for airport security can weigh as much as 300 pounds, and trace amounts of the target substances must be swabbed and inserted in the instruments' test chamber before the units can scan for them. Cooks' DESI sample collection method does not require swabbing. Instead, a puff of ionized water vapor absorbs any trace substance on a scanned item and transfers the sample to the mass spectrometer's ion trap. The control computer then reads out the mass of the elements in the compound and matches that data against the patterns saved in the unit's database. The entire procedure takes less than a second.
"The advantage of DESI is that many military explosives, as well as most biological compounds, do not give off vapors," said Cooks. "We compare [our unit] to the Star Trek tricorder because it is not only handheld but can determine the precise chemical composition of a substance noninvasively."
The noninvasive aspect could suit the device for medical applications, such as scanning for biomarkers that provide an early warning of disease. Cooks also predicts that the food-processing industry will use the device to detect bacterial contaminants before food products leave the plant.