Scientists at Penn State have designed and tested a stretchable and wearable gas sensor for environmental sensing, in collaboration with Northeastern University and five universities in China.
The sensor has been made with a combination of a newly developed laser-induced graphene foam material and a particular form of molybdenum disulfide along with reduced-graphene oxide nanocomposites.
The team was keen on observing how distinct morphologies, or shapes, of the gas-sensitive nanocomposites influence the sensitivity of the material in detecting nitrogen dioxide molecules at very low concentration. They altered the morphology by packing a container with salt crystals that were ground very finely.
Nitrogen dioxide is a toxic gas discharged by vehicles and can trouble the lungs at low concentrations and result in disease and death at higher concentrations.
The addition of molybdenum disulfide and reduced graphene oxide precursors to the canister led to the formation of structures by the nanocomposites in the tiny gaps between the salt crystals.
The researchers tested this with a range of salt sizes and performed sensitivity tests on the newly developed laser-induced graphene platform and traditional interdigitated electrodes. Once the salt was eliminated by dissolving in water, the team found that the tiniest salt crystals helped develop the most sensitive sensor.
We have done the testing to 1 part per million and lower concentrations, which could be 10 times better than conventional design. This is a rather modest complexity compared to the best conventional technology which requires high-resolution lithography in a cleanroom.
Huanyu Larry Cheng, Assistant Professor, Engineering Science and Mechanics and Materials Science and Engineering, Penn State
According to Ning Yi and Han Li, co-authors of the paper published in Materials Today Physics, “The paper investigated the sensing performance of the reduced graphene oxide/moly disulfide composite. More importantly, we find a way 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.”
We think the stretchable nitrogen dioxide gas sensor may find applications in real-time environmental monitoring or the healthcare industry.
Ning Yi and Han Li, Doctoral Students, Penn State
Other authors of the study Penn State are Li Yang, Jia Zhu, Xiaoqi Zheng, and Zhendong Liu.
This study was financially supported by the National Science Foundation and American Chemical Society Petroleum Research Fund, with additional support from Penn State and Northeastern.
Yi, N., et al. (2020) Stretchable, Ultrasensitive, and Low-Temperature NO2 Sensors based on rGO/MoS2 Nanocomposites. Materials Today Physics. doi.org/10.1016/j.mtphys.2020.100265.