Researchers from MIT are developing a new wearable sensor that can detect toxic gases and send signals to wireless devices to warn users when they are in danger. The sensor weighs less than a credit card and can be easily worn by military personnel on the battlefield. The sensor is a circuit loaded with carbon nanotubes. Unlike electric wire, with which most are familiar, the carbon nanotubes are insulated in a polymer, not plastic. The polymer breaks down at the introduction of toxic gases, such as Sarin gas. The loss of the insulations allows the nanotubes to become conductive, which sends a signal to a near-field communication (NFC) enabled device. NFC technology allows devices to transmit data over short distances without the need for internet connection. The sensors only cost about 5 cents each to make, and about 4 million of them can be created from just 1 gram of the carbon nanotube components. http://futurism.com/ultra-lightweight-toxic-gas-sensor-developed-at-mit/