This paper presents a feasibility study of a fully organic RFID gas sensor, realized by combining CNT deposition with inkjet printing on paper, able to achieve performance of interest for emerging applications in the field of Internet of Things (IoT) and Large Area Electronics (LAE). The advancement with respect to the state of the art is made possible by adopting a more sophisticated yet simple and innovative architecture implementing a Wheatstone bridge on a harmonic tag. Tremendous margins for sensitivity improvement are demonstrated while keeping the beauty of a fully organic, autonomous and chipless realization.