New three-piece sensor works with PIXIES

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

Researchers from the University at Buffalo, New York, are developing a handheld sensor that can detect the presence of toxins used as agents in biological warfare.

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

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

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 are said to have successfully designed a prototype that detected the presence of oxygen.

According to Frank V. Bright, UB Distinguished Professor in the Department of Chemistry in the UB College of Arts and Sciences, 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 on top of 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. When the target toxin is recognised by the PIXIES, the fluorescent molecule will change its light intensity, Bright explained.

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 directed onto the face of the CMOS detector, an electrical signal is produced, which a personal digital assistant (PDA) or similar handheld device can read.

‘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,’ said 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.’

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

‘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,’ Titus adds.

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