Implementation of a Dual-Interrogation-Mode Embroidered RFID-Enabled Strain Sensor

This letter studies a dual-interrogation-mode (hybrid chip-enabled/chipless) technique to detect an embroidered radio frequency identification (RFID)-enabled sensor. We have created a hybrid RFID strain sensor utilizing both chipped and chipless approaches. A comparison between the read-range extraction technique, which relies upon the detection of the threshold power that is required to activate an RFID IC, and a radar-cross-section (RCS)-based technique that does not require any protocol is presented. An embroidered RFID sensor with an electrical length that is directly linked to the applied strain is realized and interrogated using both techniques. The sensitivities for the chipless radar technique and for the chip-enabled read range extraction technique are 0.66% and 0.43% frequency shift, respectively, for 1% strain variation. Simulations and measurements validate the dual interrogation mode and provide the proof of concept that a chip-enabled RFID sensor tag can be detected accurately utilizing backscattering RCS measurements.