Broad-Range Fast Response Vacuum Pressure Sensors Based on a Graphene Nanocomposite with Hollow α-Fe₂O₃ Microspheres

This paper demonstrates the application of a graphene–ferric oxide (hollow mesoporous α-Fe2O3 microspheres) nanocomposite for the measurement of vacuum pressure. Numerous research and industrial systems essentially require a vacuum environment, and therefore, measurement of vacuum becomes vital for their efficient functioning. The presented graphene nanocomposite vacuum pressure sensor (GnVS) is fabricated using a reduced graphene oxide (rGO)/α-Fe2O3 nanocomposite synthesized by a facile and safe hydrothermal process. This sensor has an impressive operating range spanning 9 orders of magnitude down from atmospheric pressure (103 mbar) to high vacuum (∼4 × 10–6 mbar), a remarkable sensitivity of 2 × 10–4 mbar–1, and a response/recovery time of ∼3 s, which are major improvements over the reported graphene- and rGO-based vacuum sensors. The reason behind the exceptional device performance is proposed to be a coaction of gas chemisorption on sensor surface, thermal conductivity of the sensing material, and varying van der Waals force between rGO layers. The temperature dependence of the sensor has been examined, and an appropriate temperature compensation technique is suggested. GnVS promises to bring a one-step vacuum measurement solution with its high sensitivity, repeatability, broad range, simple cost-effective design, and potential to revolutionize the vacuum sensing technology.