Bangalore: Cell phones have increasingly become mobile labs and tech tools for researchers, and now NASA has gotten in on the act. A NASA scientist has developed a postage-stamp-sized chemical sensor that allows iPhones to sniff out low airborne concentrations of chemicals such as ammonia, chlorine gas and methane.

The gadget add-on comes courtesy of Jing Li, a Physical Scientist at NASA's Ames Research Center in California. She developed the proof of concept with other researchers as part of Homeland Security's 'Cell-All' program, which aims to put more mobile sensors in the hands of every cell phone user, reports Popular Science.

A puff from a 'sample jet' helps sense any airborne chemicals. That information gets processed by a silicon chip consisting of 16 nano-sensors, and then passes on to another phone or computer through any Wi-Fi or telecom network.

Such sensors could alert first responders early if there's a chemical accident or attack, even if the unfortunate cell phone user has already passed out. This is an addition to other cell phone tools such as off-the-shelf microscopes and watchful heart monitors.