Engineers at MIT have used carbon nanotubes to make a tiny new mobile chemical sensor.

The low-cost chemical sensors enable smartphones and other wireless devices to detect trace amounts of toxic gases.

The researchers are using the sensors in lightweight, inexpensive radio-frequency identification (RFID) badges, which could be worn by anyone who needs to rapidly detect the presence of toxic fumes, leaks, and even chemical weapon.

They are sensitive enough to detect less than 10 parts per million of target toxic gases in a matter of seconds.

“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,” MIT researcher Timothy Swager says.

The sensor is a circuit loaded with carbon nanotubes, which are normally highly conductive but have been wrapped in an insulating material that keeps them in a highly resistive state.

When exposed to certain toxic gases, the insulating material breaks apart, and the nanotubes become significantly more conductive.

This sends a signal that can be picked up by a smartphone with near-field communication (NFC) technology, which allows devices to transmit data over short distances.

The sensors cost just a few cents each to make; just a single gram of carbon nanotube material can produce roughly 4 million sensors.

“You really can't make anything cheaper,” Swager says.

“That's a way of getting distributed sensing into many people's hands.”

More information is available in the full report, here.