At Pacific Northwest National Laboratory, researchers are conducting cutting edge work to build highly efficient, noninvasive sensors based on carbon nanotube technologies. For example, researchers are building a sensor based on enzymes that self-assemble layer by layer onto tiny hallow carbon tubes. When the sensor encounters organophosphates, the active agent in certain insecticides and chemical warfare agents, the enzymes slow down. The reduced activity is transmitted as an electrochemical signal through the carbon nanotubes to the attached electrode. The resulting measurements can show the concentration of organophosphates in a person's saliva, a city's water supply, or other contaminated waters.