We have developed chemical sensors consisting of a single-walled carbon nanotube field effect transistor (swCN-FET) with a nanoscale layer of single stranded DNA (ssDNA) adsorbed to the tube’s outerwall. The current through the swCN-FET shows a characteristic response to gaseous analytes. This response varies depending on the base sequence of the adsorbed ssDNA.These sensors have been able to detect methanol, trimethylamine, propionic acid, dimethyl methylphosphonate (a simulant of sarin), and dinitrotoluene (a derivative of TNT) at the ppm level. The response and recovery of this biosensor is on the order of seconds.
Full Article & image from: http://nanophys.seas.upenn.edu/biosensors.html