title: Passive UHF RFID Tag for Multispectral Assessment.
abstract: 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.
authors.affiliation: ECsens, CITIC-UGR, Department of Electronic and Computer Technology, ETSIIT University of Granada, Granada E-18071, Spain. pabloescobedo@ugr.es.
authors.forename: Pablo
authors.initials: P
authors.lastname: Escobedo
authors.affiliation: ECsens, CITIC-UGR, Department of Electronic and Computer Technology, ETSIIT University of Granada, Granada E-18071, Spain. carvajal@ugr.es.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Carvajal
authors.affiliation: ECsens, Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Granada E-18071, Spain. lcapitan@ugr.es.
authors.forename: Luis F
authors.initials: LF
authors.lastname: Capitán-Vallvey
authors.affiliation: Institute for Nanoelectronics, Technical University of Munich, Munich DE-80333, Germany. jfsalmeron@nano.ei.tum.de.
authors.forename: José
authors.initials: J
authors.lastname: Fernández-Salmerón
authors.affiliation: ECsens, CITIC-UGR, Department of Electronic and Computer Technology, ETSIIT University of Granada, Granada E-18071, Spain. amartinez@ugr.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Martínez-Olmos
authors.affiliation: ECsens, CITIC-UGR, Department of Electronic and Computer Technology, ETSIIT University of Granada, Granada E-18071, Spain. ajpalma@ugr.es.
authors.forename: Alberto J
authors.initials: AJ
authors.lastname: Palma
keywords: microcontroller; optical sensor; passive RFID tag; printed electronics; screen printing; spectral fingerprint