Portable sensor detects trace elements of greenhouse gasses

The device, created by Rice engineer Frank Tittel and his group, uses a thumbnail-sized quantum cascade laser (QCL) as well as tuning forks to detect very small amounts of nitrous oxide and methane.

The QCL emits light from the mid- to far-infrared portion of the spectrum, allowing for better detection of gases than more common lasers that operate in the near-infrared.

The technique, quartz-enhanced photoacoustic absorption spectroscopy (QEPAS), was invented at Rice by Tittel, Prof Robert Curl and their collaborators in 2002. The Rice team’s new device is detailed in the Royal Society of Chemistry journal Analyst.

In tests, the device detected trace amounts of methane, 13 parts per billion by volume (ppbv), and nitrous oxide, six ppbv.

‘Methane and nitrous oxide are both significant greenhouse gases emitted from human activities,’ Tittel said in a statement. ‘The warming impact of methane and nitrous oxide is more than 20 and 300 times, respectively, greater compared to the most prevalent greenhouse gas, carbon dioxide over a 100-year period. For these reasons, methane and nitrous oxide detection is crucial to environmental considerations.’