Sensitive sensor

Researchers at Ohio State University have developed a sensor that can detect emissions from cars, power plants, and other combustion processes.

Prabir Dutta, professor and chair of chemistry at Ohio State, said the newly-patented sensor represents a step forward in sensor development because it can detect the total amount of NOx from the complex mixtures that make up combustion exhaust in small amounts and in a rapid fashion.

Specifically, Dutta and former graduate student Nicholas Szabo designed the sensor with a zeolite filter inside to remove carbon monoxide from the airstream. The NOx passes through the filter to an electrode that then registers a signal that is proportional to the concentration of NOx.

The sensor can survive temperatures greater than 1,000 degrees F – a prerequisite for working near an engine or furnace. In laboratory tests, the sensor accurately detected the presence of NOx in concentrations above 100 parts per million – sensitivity adequate for car and power plant exhaust.

But the researchers goal is to develop a sensor that will detect concentrations well below 100 parts per million, which Dutta said will be needed for more environmentally friendly engines in the future. A more sensitive detector would also be needed for turbine engines for aircraft and power applications, he said.

The sensor currently measures half a centimetre (about a quarter of an inch) across, but eventually the scientists want to shrink it thousands of times smaller.

Several commercial companies are trying out the sensor for various applications.

Meanwhile, Henk Verweij, professor of materials science and engineering at Ohio State, is studying the sensor packaging to make it easier to manufacture. And Giorgio Rizzoni, professor of mechanical engineering and director of the university’s Center for Automotive Research and Intelligent Transportation, leads a team that is testing its performance at monitoring car engines.

Future plans include miniaturising the sensors and building them into an array to monitor the combustion process in the boiler of power plants. With the right software, data from sensors at different locations in the boiler can be used to balance individual burners to better control emissions and improve efficiency. The software algorithms are being developed at the university’s Center for Industrial Sensors and Measurements (CISM), where Dutta is co-director.

Carl Palmer, engineering leader at GE Reuter Stokes of Twinsburg, OH, and his colleagues will test the sensor array. Other collaborators include Sheikh Akbar, professor of materials science and engineering and founding director of CISM, and Bruce Patton, professor of physics.

“This is a truly multidisciplinary project,” Dutta said. “This is something a chemist can’t do alone.”

The State of Ohio, CISM, NASA Glenn Research Center, and the Department of Energy all funded the work.