A new approach to electronic noses is based on carbon nanotubes. A team from the University of Pennsylvania and the Monell Chemical Sensors Center in Philadelphia has taken single-strand DNA molecules that are tailored to bind to certain molecules and stuck them onto carbon nanotubes.

When the DNA molecules pick up molecules from the air, they either lose or gain electrons and this changes the charge on a nanotube and in turn affects how much current it can carry. The sensors are quite fast, "picking up a scent" in about 10 seconds and needing just 30 seconds to recover. Such devices could form the basis for a new generation of chemical sensors.

Further reading

Cristian Staii et al. 2005 Nano Letters 5 (9) 1774.