A team has developed and tested a stretchable, wearable gas sensor for environmental sensing. It combines a newly developed laser-induced graphene foam material with a unique form of molybdenum disulfide and reduced-graphene oxide nanocomposites. The researchers were interested in seeing how different morphologies, or shapes, of the gas-sensitive nanocomposites affect the sensitivity of the material to detecting nitrogen dioxide molecules at very low concentration. To change the morphology, they packed a container with very finely ground salt crystals.
Nitrogen dioxide is a noxious gas emitted by vehicles that can irritate the lungs at low concentrations and lead to disease and death at high concentrations. When the researchers added molybdenum disulfide and reduced graphene oxide precursors to the canister, the nanocomposites formed structures in the small spaces between the salt crystals. They tried this with a variety of different salt sizes and tested the sensitivity on conventional interdigitated electrodes as well as the laser-induced graphene platform. When the salt was removed by dissolving in water, the researchers determined that the smallest salt crystals enabled the most sensitive sensor.
The testing was done to 1 part per million and lower concentrations, which could be 10 times better than conventional design. The team was able to enhance the sensitivity and signal-to-noise ratio of the gas sensor by controlling the morphology of the composite material and the configuration of the sensor-testing platform.