Wearable sensors
Wearable sensors are the new entrants to the stream of portable health monitoring devices. The sensors when coming in contact with the surface of the skin, reveal body signals like heart rate. Breath markers, etc. and ambient signals such as toxic gases and ultraviolet radiation. Case in point being smart bands from various techno-giants like Xiaomi and Huawei.
Researchers from Northeastern University, Penn State, and five other universities in China have developed and tested a wearable and stretchable gas sensor for the purpose of health monitoring and environmental monitoring.
Substrate:
It is a newly developed laser-induced graphene foam material with a unique combination of molybdenum disulfide and reduced oxide nanocomposites. The researchers were interested in having a look at the change in shapes and morphologies by using nanocomposites to determine the sensitivity of the material and also to detect the low concentration nitrogen oxide molecules. To have a change in morphology, finely grounded salt crystals packed in a container were used.
Nitrogen dioxide molecules of low concentration, emitted from automobiles easily affect the lungs, while the high concentrated molecules may even lead to death.
Mechanism:
The nanocomposites, when added with molybdenum disulphide and graphene oxide, formed small structures in the salt crystals. The procedure was carried to different sizes of salt crystals to test the sensitivity on conventional electrodes, as well as the newly developed laser-induced graphene material. It was found that the smallest crystal structures to be the most sensitive sensors when dissolved in water.
As reported by Huanyu Larry Cheng, Assistant Professor in the field of Engineering Science and Mechanics and Material Science and Engineering, the testing was carried on to 1 ppm (part per million) and lower concentration, which could better the conventional design by 10 times. It was found to be better because of the complexity involved in the conventional technology. Conventional technology requires high-resolution lithography in a clean room, which is quite a challenging piece of work.
According to Ning Yi and Han Li, co-authors of a paper in Materials Today Physics and doctoral students at Penn State, the research was carried out to probe into the sensitivity of the reduced graphene oxide/ molybdenum disulphide composite. In addition to this, by controlling the morphology between the composite material and the laser-induced graphene platform, the research paved them a way to enhance the sensitivity and the signal-to-noise ratio of the gas sensor.
They concluded by saying that these gas sensors may very well find their way in real-time healthcare and environmental monitoring.
