▎ 摘　　要

Graphene is widely regarded as one of the most promising materials for sensor applications. Here, we demonstrate that a pristine graphene can detect gas molecules at extremely low concentrations with detection limits as low as 158 parts-per-quadrillion (ppq) for a range of gas molecules at room temperature. The unprecedented sensitivity was achieved by applying our recently developed concept of continuous in situ cleaning of the sensing material with ultraviolet light. The simplicity of the concept, together with graphene's flexibility to be used on various platforms, is expected to intrigue more investigations to develop ever more sensitive sensors. 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742327]