Multi-chip RFID antenna integrating shape-memory alloys for temperature sensing

This paper proposes a dual-chip UHF tag embedding Shape Memory Alloys (SMA) able to tranform the variation of the tagged item´s temperature into a permanent change of antenna radiation features. This event-driven antenna is hence able to selectively activate the embedded microchips according to the temperature above or below a given threshold. A general design methodology for the resulting two-ports tag antenna is here introduced and then applied to prototypes able to work at low (around 0°C) and high (80°C) temperatures. The devices has clear applications in supply chain management as well as general safety assessment.