Nikhil Koratkar

Using carbon nanotubes designed to detect toxic gases and chemical warfare agents, Rensselaer researchers are taking the development of nanoscale chemical sensors to a new level. The project is being funded through a recent $1.3 million Nanoscale Interdisciplinary Research Team (NIRT) grant from the National Science Foundation (NSF).

In 2003, the same research team developed a prototype sensor that demonstrated definitive identification of contaminants in real time. The prototype is a breakthrough from traditional electrical-conductivity-based gas detectors.

The new NSF grant will support research to boost the sensitivity of the device from identifying gases at concentrations of parts per hundred, as in the prototype, to parts per million, says Nikhil Koratkar, assistant professor of mechanical, aerospace, and nuclear engineering, who is principal investigator on the project. To do this, his team will examine how the size, shape, and density of the nanotubes and the overall geometry of the device affect the sensitivity levels.

“Traditionally, it could take several days to get gas analysis results back from a lab, but first responders don’t have that kind of time. They need answers immediately,” Koratkar says. “We are working to develop a system that alerts them to dangers in real time at the site of an emergency using a device that is battery-powered and transportable, such as a coin-sized device worn on a uniform or on a vehicle.”

In the prototype, billions of carbon nanotubes sit in a silicon substrate. The sharp tips of the tubes greatly amplify the surrounding electric field, inducing ionization and electrical breakdown of gases at low voltages. All gases are classified by their different breakdown voltages — essentially a dictionary of gas fingerprints. Once the voltage fingerprint is known, the gas can be identified. By monitoring the discharge current, it is possible to determine the gas concentration, says Koratkar. The team’s research was published recently in Nature.


Originally published in Rensselaer Magazine, Fall 2004
Photo by Paul Castle

Published October 1, 2004