Flexible graphene gas sensors based on ultraviolet illumination enhancement for o-dichlorobenzene detection

o-Dichlorobenzene (o-DCB) is extremely toxic which can cause serious damage to human health at ppb (parts per billion) level. Aiming at the increasing requirement of real-time environmental monitoring, traditional solid-state sensors based on metal-oxide transistors have sensitivity only at 10 ppb level with low selectivity, high power consumption and high operation temperature. In this paper, a new flexible gas sensor was demonstrated by using a bilayer film composed of modified graphene and polymethyl methacrylate (PMMA) to upgrade the sensor performance. The surface of graphene irradiated with ultraviolet (UV) light produces oxygen-containing groups, which increases the chemical activity of graphene reacted with o-DCB and improves the sensitivity to 5 ppb by optimizing the UV irradiation time and the thickness of the PMMA layer. Besides, the sensors after bended also be highly developed due to the enforced hydrogen bonding between the PMMA polymer buffer layer and graphene, which can effectively reduce the damage of graphene film caused by external stress. Furthermore, the device displays good selectivity and reproducibility at different humidity and temperature, which suggests its potential application in complex environments.