Passive UHF RFID Tag for Multispectral Assessmen Escobedo Araque, Pablo Carvajal Rodríguez, Miguel Ángel Capitán Vallvey, Luis Fermín Fernández-Salmerón, José Martínez Olmos, Antonio Palma López, Alberto José Screen printing Printed electronics Passive RFID tag Optical sensor Microcontroller Spectral fingerprint This work presents the design, fabrication, and characterization of a passive printed radiofrequency identification tag in the ultra-high-frequency band with multiple optical sensing capabilities. This tag includes five photodiodes to cover a wide spectral range from near-infrared to visible and ultraviolet spectral regions. The tag antenna and circuit connections have been screen-printed on a flexible polymeric substrate. An ultra-low-power microcontroller-based switch has been included to measure the five magnitudes issuing from the optical sensors, providing a spectral fingerprint of the incident electromagnetic radiation from ultraviolet to infrared, without requiring energy from a battery. The normalization procedure has been designed applying illuminants, and the entire system was tested by measuring cards from a colour chart and sensing fruit ripening. 2017-02-22T11:02:27Z 2017-02-22T11:02:27Z 2016 info:eu-repo/semantics/article Escobedo, P. [et al]. Passive UHF RFID Tag for Multispectral Assessment. Sensors 2016, 16, 1085. [http://hdl.handle.net/10481/44989] 1424-8220 http://hdl.handle.net/10481/44989 spa http://creativecommons.org/licenses/by-nc-nd/3.0/ info:eu-repo/semantics/openAccess Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License MDPI