Researchers at ETH Zurich have combined sensitive gas sensors for acetone, ammonia, and isoprene – metabolic products that we emit in low concentrations via our breath or skin – with two commercial sensors for CO2 and moisture into a single measuring device.
The belief is that the sensor will be useful in rescue searches, as an alternative to sniffer dogs.
"The combination of sensors for various chemical compounds is important, because the individual substances could come from sources other than humans. CO2, for example, could come from either a buried person or a fire source," explains Andreas Güntner, a postdoc in Pratsinis' group and lead author of the study.
The ETH scientists' gas sensors are the size of a small computer chip. "They are about as sensitive as most ion mobility spectrometers, which cost thousands of Swiss francs and are the size of a suitcase," says Professor Sotiris Pratsinis of ETH Zurich. "Our easy-to-handle sensor combination is by far the smallest and cheapest device that is sufficiently sensitive to detect entrapped people. In a next step, we would like to test it during real conditions, to see whether it is suited for use in searches after earthquakes or avalanches."
While electronic devices are already in use during searches after earthquakes, these work with microphones and cameras and only help to locate entrapped people who are capable of making themselves heard or are visible beneath ruins.
The ETH scientists' idea is to complement these resources with the chemical sensors. They are currently looking for industry partners or investors to support the construction of a prototype. Drones and robots could also be equipped with the gas sensors, allowing difficult-to-reach or inaccessible areas to also be searched. Further potential applications could include detecting stowaways and exposing human trafficking.