A method and structure for a radio frequency identification (RFID) sensor that may be used to monitor various environmental conditions. The environmental condition measured depends on a sensor material used in the RFID sensor. The sensor material is selected based on a flux in electrical conductivity relative to its saturation of the environmental condition being monitored. The sensor material is placed between adjacent electrically conductive structures of the RFID sensor. Upon a change in the environmental condition being measure, the electrical conductivity of the sensor material changes, thereby increasing or decreasing an amplitude of a response by the RFID sensor to an interrogation by an RFID reader.

A radio frequency identification (RFID) tag and reader system including an array of circular resonators with interdigitated capacitor fingers wherein the fingers of each pair are radially aligned and bars disposed between the resonators to reduce coupling between adjacent resonators, wherein subsets of the resonators resonate at respective different resonant frequencies, and the resonators of each of the subsets have the same resonant frequency; and the radio frequency response produced by the tag at a resonant frequency varies depending on the activation of resonators of the subset corresponding to the resonant frequency.

A method implemented in an electronic entity capable of implementing a plurality of applications includes the following steps: detecting an electrical signal (D; D′); reading, in a memory of the electronic entity, information relating, among the plurality of applications, to a previously selected application; and transmitting a command (CMD) to deliver an indication associated with the application to which the read information relates. An associated electronic entity is also described.

A method implemented in an electronic entity capable of implementing a plurality of applications includes the following steps: detecting an electrical signal (D; D); reading, in a memory of the electronic entity, information relating, among the plurality of applications, to a previously selected application; and transmitting a command (CMD) to deliver an indication associated with the application to which the read information relates. An associated electronic entity is also described.

The reconfigurable resonators for chipless RFID applications provide spiral resonators for a multiple resonator passive RFID transponder tag. Each spiral resonator includes a U-shaped frame of conductive material and has a plurality (K1) of parallel adjusting or shorting elements disposed between the legs of the U-shaped frame. Each resonator has one leg coupled to a transmission line adapted for connection between a receiving antenna and a transmitting antenna (in some embodiments, a single antenna may be used for both receiving and transmitting), and one of the adjusting or shorting elements may be selectively connected to the opposing leg of the frame to configure the resonator to resonate at one of (K1) different resonant frequencies (K frequencies if none of the elements are connected) by a short metal jumper strip to change the length of the spiral resonator.

A radio frequency identification (RFID) tag and reader system including an array of circular resonators with interdigitated capacitor fingers wherein the fingers of each pair are radially aligned and bars disposed between the resonators to reduce coupling between adjacent resonators, wherein subsets of the resonators resonate at respective different resonant frequencies, and the resonators of each of the subsets have the same resonant frequency; and the radio frequency response produced by the tag at a resonant frequency varies depending on the activation of resonators of the subset corresponding to the resonant frequency.

A method and structure for a radio frequency identification (RFID) sensor that may be used to monitor various environmental conditions. The environmental condition measured depends on a sensor material used in the RFID sensor. The sensor material is selected based on a flux in electrical conductivity relative to its saturation of the environmental condition being monitored. The sensor material is placed between adjacent electrically conductive structures of the RFID sensor. Upon a change in the environmental condition being measure, the electrical conductivity of the sensor material changes, thereby increasing or decreasing an amplitude of a response by the RFID sensor to an interrogation by an RFID reader.