A novel and miniaturized semi-elliptical 20-bit fully passive chipless RFID sensor tag is proposed in this article. The realized sensor tag is made up of semi-elliptical shaped open-end slots within the compact size of 25 mm x 17 mm. The multi-substrate analysis of the proposed tag is examined using non-flexible and flexible materials. The articulated tag configuration is capable of monitoring moisture levels when the largest resonator is covered by a heat-resistant sheet of Kapton HN (DuPontTM). The proposed tag functions in the operational frequency band of 4.1 GHz-16 GHz and possesses the overall bit density of 4.70 bit/cm(2). The structure is composed of a thin passive substrate layer topped with an active layer of conductive path and is considered as a potential candidate for low-cost identification of the tagged objects. In addition to that, its moisture sensing property and flexible nature make it a reliable smart sensor for conformal applications
