University at Buffalo - The State University of New York

Published: December 4, 2003

By JOHN DELLA CONTRADA
Contributing Editor

Researchers from UB are developing a handheld sensor that can detect the presence of toxins potentially used as agents in biological warfare.

The proposed sensor, which will utilize optical-detection and chemical-sensing technologies, could be used in urban, military, industrial and even home environments, says researcher Albert H. Titus, assistant professor of electrical engineering in the School of Engineering and Applied Sciences.

"Our sensor will have certain advantages over what is currently available," Titus says. "It will be lightweight, portable, relatively inexpensive to manufacture and it can be tailored to detect many types—or different quantities—of toxins."

Titus and co-researchers Frank V. Bright, UB Distinguished Professor in the Department of Chemistry in the College of Arts and Sciences, and Alexander N. Cartwright, associate professor of electrical engineering, have been awarded a $300,000 grant from the National Science Foundation to develop the sensor.

The sensor will be composed of three components—an LED (light emitting diode), a xerogel-based sensor array and a CMOS (complementary metal-oxide semiconductor) detector, commonly used in miniature digital cameras.

In experiments using this sensing system, the researchers successfully designed a prototype that detected the presence of oxygen.

According to Bright, the xerogel—a porous, glass-like material—will be custom-designed by imprinting the glass with the protein-based toxins that one seeks to detect, such as staphylococcal, botulinum and shiga toxins.

To detect the presence of the toxins, the researchers will produce sensors called Protein Imprinted Xerogel with Integrated Emission Sites (PIXIES). Within the PIXIES, a tiny fluorescent dye molecule is placed within the xerogel's imprint sight. The PIXIES then are placed atop the LED, which is used to stimulate the fluorescent dye to emit light.

The fluorescent molecule is sensitive to the presence of other molecules in its immediate environment. Thus, when the target toxin is recognized by the PIXIES, the fluorescent molecule will change its light intensity, Bright explains.

The PIXIES can be constructed to detect many different toxins or to detect the same toxin in different ways, as a failsafe. When light from the PIXIES is imaged onto the face of the CMOS detector, an electrical signal is produced, which can be read by a personal digital assistant (PDA) or similar handheld device.

"The light output from the PIXIES will be very different depending on the presence or absence of the toxin that you are trying to detect," says Bright. "Changes to one or more of the many PIXIES indicate which toxin is present, and the intensity of the detected light indicates how much of that toxin is present."

The compact size and low-power requirements of the sensor will make it ideal for connection to a PDA or for inclusion within a cell phone that would emit a signal alerting the user to the presence of a toxin, Titus points out.

"These sensors can be placed at sites for monitoring the environment to warn of attacks, to assess the nature of attacks and to identify a toxin's concentration," he adds.

The sensor also will have medical applications, Bright notes. It can be adapted to detect glucose, pharmaceuticals or biomarkers in blood or saliva, and may serve as a diagnostic tool for assessing disease.