PORTLAND, Ore. A wide net that has been cast to create integrated bio- and chemical-agent sensors following terrorist threats on U.S. territory has reeled in a novel handheld biological-warfare agent design.
The handheld device, which recently got the green light from the National Science Foundation, is based on a prototype sensor developed at the University of Buffalo. The unit combines an LED with protein-imprinted xerogels with integrated emission sites (Pixies) and a CMOS detector.
"The protein-imprinted xerogels with integrated emission sites are nanoscopically porous glasses that are formed by a molecular-imprinting strategy. The fluorescence from the Pixies changes in intensity in the presence or absence of the molecule that is used to imprint the xerogel," said professor Albert Titus, who works in the electrical engineering department at the University of Buffalo. He performed the research with fellow electrical-engineering professor Alexander Cartwright and chemistry professor Frank Bright.
According to Titus, xerogels are in essence "templated" with the molecule to be detected. The template sites are labeled with a fluorescent "reporter molecule." Then the LED turns on to irradiate the xerogel just above the CMOS detector. The location of any resulting fluorescence in the xerogel indicates which toxin is being sensed.
If the molecule is present, "it binds to the templated site, and its presence causes a change in the fluorescent molecule," said Titus. The change is detected by the CMOS array.
"We have used Mosis [Integrated Circuit Fabrication Service] to fabricate our prototype chips using a standard 1.6-micron technology," said Titus. "For the sensor device itself [light source, Pixie array and CMOS chip], it seems likely that the total cost would be less than $50."
The prototype device used to prove the concept and persuade the NSF to fund the handheld device's development was designed to sense oxygen. But researchers claim that a variety of different chemical and biological agents can be templated by the xerogel process, and the group has plans to fabricate the core set of most likely "terrorist" toxins into a single handheld device.
Initial agents likely to be sensed by the new handheld device include protein-based toxins such as staphylococcal, botulinum and shiga toxins, which are easy to template in the xerogel. Titus said they will also template several different proteins from the same toxin as fail safes to mitigate "false-positive" identifications. The device also detects the level of concentration of the detected toxin by measuring the intensity of the fluorescence.
Titus thinks the handheld prototype will be initially fabricated as an add-on for a wireless personal digital assistant or a smart phone. With such an arrangement, an alarm could be sent quickly to a monitoring agency once an agent is detected.