A research team from MIT has developed a new low-cost, wearable gas sensor that can be used on smartphone or other wireless devices to detect environmental toxic gases.
The sensors are made from chemically altered carbon nanotubes – a highly conductive nanomaterial. Carbon nanotubes have been wrapped in an insulating material that keeps them in a highly resistive state. When the sensors are exposed to certain toxic gases, such as nerve gas or choking agents, the carbon nanotubes touch each other and the sensors become significantly more conductive. The response signal is readable by smartphone with near-field communication (NFC) technology, which allows the transmission of the data to short distances.
The sensors are highly sensitive and they can detect less than 10 parts per million of toxic gases within few seconds. Moreover, the sensors can be made at low cost and each costs about a nickel. One gram of carbon nanotube materials can roughly generate 4 million sensors. “You really can’t make anything cheaper,” Professor Timothy Swager says. “That’s a way of getting distributed sensing into many people’s hands.”
The toxic gas sensors are also lightweight. “Soldiers have all this extra equipment that ends up weighing way too much and they can’t sustain it,” says Professor Timothy Swager. “We have something that would weigh less than a credit card. And soldiers already have wireless technologies with them, so it’s something that can be readily integrated into a soldier’s uniform that can give them a protective capacity.”
In addition to being lightweight and cheap, the sensors also work as well as laboratory equipment that is much bulkier and much more expensive. “We are matching what you could do with benchtop laboratory equipment, such as gas chromatographs and spectrometers, that is far more expensive and requires skilled operators to use,” Swager said.
The next step of the project is to test those sensors with live chemical agents outside the lab that are much harder to detect. They also have future plans to create a mobile app that can indicate both the presence and specific concentrations of toxic gases. This will involve the measurement of the signal strength of an NFC tag: the signal differences indicate the levels of toxic gases in the environment.
This technology has been licensed by C2Sense.
More information can be found at:
Ultratrace Detection of Toxic Chemicals: Triggered Disassembly of Supramolecular Nanotube Wrappers