Explosives such as trinitrotoluene (TNT) are difficult to detect because of their low volatilities under everyday conditions. Denis Spitzer of the French–German Institute of Saint-Louis, France, and his colleagues have created a device that they estimate can sniff out less than one part per trillion of TNT.
The team coated a tiny, vibrating cantilever with vertically aligned titanium dioxide (TiO2) nanotubes (pictured). TNT binds to the nanotubes, altering the frequency of the vibration. The device's sensitivity is due to the nanotubes' structure and large surface area, and to the strong affinity of TiO2 for TNT. The detector is much less sensitive to other compounds, which reduces the likelihood of false positives.
The researchers are now adapting their sensor to detect additional chemicals, including other types of explosive.
Angew. Chem. Int. Ed. http://dx.doi.org/10.1002/anie.201108251 (2012)