Skip to content

Cheap Sensor Can Detect Trace Amounts of Toxin and TNT in Water, Researchers Report

09/28/2009 -Researchers at Stanford University have developed a new hypersensitive sensor that they hope will help protect the nation's water supply from contamination by terrorists or industrial leaching, the university reports.

The flexible and disposable chip constructed of carbon nanotubes can detect both trace amounts of TNT, the explosive, and a close chemical cousin of sarin, the nerve agent feared for its possible use by terrorists. In tests, the chip detected 2 parts per billion of either TNT or the sarin cousin when researchers exposed it to contaminated water.

The researchers believe their work could provide significant advances in explosives and toxin detection in water systems, according to the university.

Traces of TNT can leach into streams near munitions-making and testing sites, and then be detected downstream.

Terrorists could try to mix sarin into a reservoir or water mains. An electronic sensor that can instantly detect very low concentrations in water would be a desirable technology for staying ahead of potential attacks, said chemical engineering Associate Professor Zhenan Bao , who leads the group that developed the chip.

The Bao Research Group believes its research is a novel innovation over previous sensors.

Although many researchers around the world have devised a wide variety of chemical sensors, Bao said, the Stanford chip offers a rare combination of low-cost materials, low power usage, robust and repeatable performance in water, instant response and physical flexibility. To date, lower detection limits have only been achieved with complex, expensive, non-portable optical systems.

The researchers now have to solve some more problems if they want the sensor to go operational. The researchers will need to devise a way to package the chips in a field device that includes a power supply and a wireless transmitter. Second, the researchers will need to create more sophisticated nanotube circuitry that can sift through all the chemicals found in real-life water supplies.

♦ Photo bybixentro/Flickr