Portland, Ore. - As government workers closed three Senate office buildings last week after intercepting a letter containing the deadly poison ricin, researchers at Pennsylvania State University said they have developed a cheap, wireless, ready-to-go sensor able to detect ricin and as many as nine other toxins simultaneously.
"We think we have the solution for early-warning systems, because our sensor is made from the same magnetoelastic ribbons used for shoplifting prevention," said Pennsylvania State professor Craig Grimes. "We only need about a 6-mm snippet of a ribbon that costs about $250 for a kilometer length."
Grimes said the sensor is available now, works in air or in liquids and-at a cost of a nickel apiece, plastic housing included-is very inexpensive.
Like those plastic tags attached to merchandise in stores, which are sensed wirelessly as they pass through an exit, Grimes' ricin sensor sits quietly, ready to collect samples. Its magnetoelastic ribbon is polled wirelessly to determine what has been collected. Up to 10 types of toxins can be collected by his present sensor, any or all of which can be polled simultaneously to determine their current state.How it works
To prevent shoplifting, turnstile-type pillars at a store's entrances and exits emit radio frequencies that poll the magneto-elastic sensors. The sensor is removed or demagnetized when an item is purchased. But if a still-magnetized magnetoelastic sensor is present in your groceries, it will resonate at a characteristic frequency when polled by the transmitter in the door-side pillars. Antennas in the pillars pick up the resonating frequency of the polled sensor and set off an alarm.
To turn the magnetoelastic material into a ricin sensor, Grimes coats its surface with either a ricin antibody, for underwater detection, or glycosphingolipids, to sniff out ricin particles in the air.
While the antibodies, which bond only to ricin molecules, are a traditional detection device, the glycosphingolipids coating was specially developed by Grimes in collaboration with Cara-Lynne Schengrund, a biochemistry professor at Penn State.
The special coating would be needed to detect the kind of airborne ricin that killed 12 on Tokyo's subway system in 1995.
To detect different toxins simultaneously, Grimes installs separate sensor strips for the target toxins. Each strip's surface is coated for a different toxin and each strip is a different length so that each has a characteristic resonant frequency. All the sensor strips are bonded to a central "I-beam," in length order, so the result looks like a tiny Christmas-tree logo about a quarter-inch high for a 10-toxin sensor.