Inkjet-printed Van-Atta reflectarray sensors: A new paradigm for long-range chipless low cost ubiquitous Smart Skin sensors of the Internet of Things

In this effort, the authors improve upon most of the limitations of state-of-the-art chipless sensing technologies, by introducing a novel, and demonstrably robust, platform and reading scheme for long-range, wireless sensing. This platform was built upon a fully-inkjet printed and flexible 30GHz square patch antenna Van-Atta reflect-array, which provides high RCS over a broad range of interrogation angles, with only a 10 dB decrease in RCS at ±70 degrees from boresight. Furthermore, the signal reflected by the structure is cross-polarized with respect to that of the impinging wave, providing high polarimetric detectability. For this first application, the device was fully inkjet-printed on a polyimide (Kapton) substrate, whose humidity-dependent permittivity was taken advantage of, associated with an appropriate high performance signal processing scheme, in order to provide the first long-range capable, fully-printed chipless flexible sensor to date.