The sensors are extremely sensitive--triggered by exposure to parts-per-billion vapor concentrations--and quick, taking only seconds to complete detection and to reset after being removed from exposure, say the Science researchers.

By pairing particular liquid crystals and receptors with specific chemical properties, the sensors can be tailored to detect specific compounds. Multiple receptor/liquid crystal combinations can be patterned over the sensor's surface, allowing simultaneous detection of several different chemicals.

The "competitive binding" mechanism also allows the sensor to tolerate non-targeted compounds, such as water, which can interfere with detection in other types of sensors, says Abbott. In this case, the non-target forms an even weaker bond with the receptor than the liquid crystal, and is unable to dislodge it.

Shah and Abbott's sensors can be used to measure cumulative exposure over time, by measuring the spread of the targeted chemical across the liquid crystal, and the sensor surfaces can also be designed to trigger an instantaneous response upon exposure.

The researchers hope that their sensors will prove useful in food safety applications, such as monitoring levels of putrescine and cadaverine, the smelly compounds produced by rotting fish and meat, as well as sensors to detect exposure to pesticides such as diazinon and parathion.

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Contact: Ginger Pinholster
gpinhols@aaas.org
202-326-6421
American Association for the Advancement of Science
16-Aug-2001