Trained rescue dogs are the best disaster workers — their sensitive noses help them track down people buried by earthquakes or avalanches. But dogs need breaks. A new measuring device is always ready for use.
The device consists of small and extremely sensitive gas sensors for acetone, ammonia, and isoprene — all metabolic products that people emit in low concentrations via breath or skin. The sensors were combined in a device with two commercial sensors for CO2 and moisture. 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.
The research also showed that there are differences between the compounds emitted via breath and skin. Acetone and isoprene are typical substances that are exhaled. Ammonia, however, is usually emitted through the skin. In experiments in an “entrapment simulator” chamber, volunteers wore breathing masks. In the first part of the experiment, the exhaled air was channeled directly out of the chamber; in the second part, it remained inside. This allowed the scientists to create separate breath and skin emission profiles.
The gas sensors are the size of a small computer chip, and are about as sensitive as most ion mobility spectrometers, which are large and heavy. The easy-to-handle sensor combination is one of the smallest and cheapest devices that is sufficiently sensitive to detect entrapped people. In a next step, researchers will 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. These resources would be complemented with the chemical sensors. 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.