A common technology that enables short-range communication in smartphones could be used to detect airborne chemicals.

Near-field communication chips are found in half a billion mobile devices worldwide. They communicate wirelessly with small external tags and are used in contactless payment systems, for instance. A team at the Massachusetts Institute of Technology in Cambridge, led by Timothy Swager, modified the circuitry in the external tags using nanomaterials that are sensitive to certain chemicals. When a particular gas is present, the tag short-circuits and the smartphone can no longer read the tag.

By scanning combinations of tags, each of which was sensitive to a different chemical, the team could distinguish between gases including ammonia, hydrogen-peroxide vapour and water vapour — down to the level of parts per million.

Such a system could be used to detect explosives or pollution and has other applications, the authors say.

Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1415403111 (2014)