Passive UHF RFID tag for spectral fingerprint measurement

This work presents the design, fabrication and characterization of a fully passive 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. A microcontroller based switch has been implemented to measure in the same access the five magnitudes coming from the optical sensors, providing a spectral fingerprint of the incident electromagnetic radiation.