Engineers at the University of Texas (Austin) and Georgia Institute of Technology say they have built a reusable sensor that can detect nerve gas and similar toxic airborne agents without getting contaminated itself. By integrating nanoscale techniques with microelectromechanical systems, the team has created a so-called nanoelectromechanical system that is sensitive enough to detect as few as 50 molecules per billion of nerve gas. "Sensor poisoning is a persistent problem with other designs," said UT professor Li Shi. "Their active element is not a single-crystal film like ours. Nor do others operate their sensors at 500 degrees C." He described the nerve gas sensor, which he designed with professor Zhong Lin Wang from Georgia Tech, as "completely self-cleaning, yet small and low-power enough to be wearable, since it can run off a battery with a power consumption of only 3 to 4 milliwatts." Choongho Yu, a postdoctoral fellow at Lawrence Berkeley National Laboratory, assisted in the work.