Humidity sensors are critical in a wide range of applications ranging from
automotive, biomedical, chemical, and electronics industries, to scientific research
laboratories. Here we discussed widely acclaimed synthesis techniques for the
preparation of graphene and its derivatives. Graphene, along with its analogues GO,
and rGO shows improved surface properties making it sensitive to fractional change in
ambient surroundings. GO/rGO-based sensory materials owing to their distinctive
physio-chemical features appeared as a competitive sensor in comparison to the widely
used metal oxides. The enhancement in the merits of GO-based humidity sensors is
ascribed to the various functionalized groups on the GO surface. Pristine GO is
employed as a capacitive sensor, whereas reduced GO (rGO) with improved
conductivity is extensively utilized as a chemiresistive humidity sensor. Similarly,
Graphene quantum dots (GQDs) and 2D- layered graphene have been explored as
humidity sensors due to their massive scope of manipulation in properties. The chemiresistive humidity sensor gains an advantage over any type of available sensor owing to
its cost-effective fabrication, easier integration with the CMOS platform, and efficient
operation. This review aims to establish the evaluability of GO and rGO humidity
sensors and their role in the progress of the next generation of flexible sensors for the
Internet of Things (IoT).
Keywords: Composite, Capacitive, GO, GQD, Grotthuss mechanism, Humidity, Impedance, IoT, RGO, Resistive, Sensor.
