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

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

Periodic Table: And be sure to check out Theodore Gray's one-of-a-kind periodic table at periodictable.com.

2006

January

Making a Perfect Match

The Five-Minute Project in the November 2006 issue, â€The Nine-Volt Safe,†involved sliding off the top of a nine-volt battery. Although experts advised us that it is not normally dangerous, and we tried the project ourselves without incident, it has come to our attention that in rare instances, the cells inside the battery can â€vent†or rupture, potentially exposing the handler to the chemicals inside. Given even the small chance of injury related to this project, we advise you not to undertake it.