Researchers from Penn State University, Northeastern University and five universities in China teamed up to create a sensor that detects dangerous levels of nitrogen dioxide by combining laser-induced graphene foam material with molybdenum disulfide and reduced-graphene oxide nanocomposites.

An example of a flexible gas sensor worn over a knuckle. Source: Cheng Lab, Penn State

The team was interested in how morphologies of gas-sensitive nanocomposites can affect a material's sensitivity and enable it to detect nitrogen dioxide at a low concentration. Nitrogen dioxide gas irritates the lungs at low concentrations and can lead to disease and death in high concentrations.

To test the new wearable, the team added molybdenum disulfide and reduced graphene oxide precursors to a canister with some salt. The nanocomposite structures formed in the small spaces between the salt crystals. They tested this with a variety of salt sizes as well as tested the sensitivity on the conventional integrated electrodes and the new laser-induced graphene platform.

The team determined that the smallest salt crystals enabled the most sensitive sensor. The new tech has a modest complexity compared to the best conventional technology that requires high-resolution lithography in a cleanroom.

A paper on this technology was published in Materials Today Physics.