Miniature Spectrometer Can Detect Biological Hazards

Researchers at the Department of Energy's Oak Ridge National Laboratory have developed a miniature device that can identify as little as a fraction of a spore of anthrax and other biological hazards within 30 milliseconds. The Calorimetric Spectrometer (CalSpec) device technology can accurately identify biological hazards such as anthrax almost instantly.

The device can operate with only a fraction of a spore while isolating the DNA/RNA photothermal signature that allows for detection, identification and measurement of a substance.

Such prompt detection and identification of hazardous materials could greatly enhance the protection of first-responder emergency personnel and the capabilities of early warning systems. Current technologies do not provide the level of sensitivity offered by the CalSpec TM chemical, biological and DNA/RNA detection system.

Researchers Panos Datskos and Slobodan Rajiic of ORNL's Engineering Science and Technology Division developed the CalSpec technology.

ORNL has licensed the technology exclusively to Innovative American Technology of Herndon, Va., and Boca Raton, Fla.

The CalSpec can detect hazards by identifying their molecules. The molecular absorption can induce stress changes that allow for an initial detection that can be used for measurement. The identification of chemical and/or biological molecules, along with DNA/RNA, creates a photothermal signature.

The spectrometer could have a wide variety of applications in commercial industry and in homeland defense, including mass transit and airport security; in the postal industry, to protect workers and the public; and in monitoring air quality systems.

"The CalSpec detection device could provide a cost-effective and easily deployed upgrade for these systems to enable rapid detection, greater accuracy and -- most important -- increased sensitivity down to a fraction of a spore," said Jack Cummings, vice president of business development for Innovative American Technology.

ORNL and Innovative American Technology are working in a collaborative effort to commercialize the CalSpec technology. The device will be offered as both a laboratory and field-test device for chemical, biological and DNA/RNA detection. It is expected to be on the market by 2004.

"Finally, the CalSpec-based approach is a novel absorption spectroscopy technique that may allow us to reach detection limits of one part per trillion. The principle behind this calorimetry spectrometry technique is depicted schematically in Fig. 2. Chemical detection using CalSpec occurs in a two-step process.

In the first step, the target molecules enter the device and are allowed to interact with, and adsorb onto, the surfaces of ultrasensitive micromechanical thermal detectors. These detectors sense the sample's changes in temperature as it absorbs photons from an IR source.

In the second step, a calorimetric (photothermal) spectrum is obtained by scanning a broadband wavelength region with the aid of a monochromator, which disperses photons according to their wavelenths. For wavelengths at which the target molecules absorb incident photons, heat is generated, causing a temperature change in those particular thermal detectors. In response to these temperature changes, the detectors produce a photothermal spectrum that indicates that the target chemical has been detected and reveals its concentration in air.

A critical element of CalSpec is the thermal detector. We have used recently developed micromechanical thermal detectors made from silicon nitride. We can modify and optimize these microstructures by using focused ion-beam (FIB) milling. In FIB an intense ion beam is precisely focused on parts of the microstructure to selectively remove material and produce a new shape. "

From (and more detail at):

http://infosrv1.ctd.ornl.gov/ORNLReview/measure/analy/minia/mini.htm

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