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.

Provided is a method for encoding chipless RFID tags in real-time. The method includes exposing a chipless RFID transponder to a conductive material, the RFID transponder comprising an antenna and a plurality of resonant structures, the plurality of resonant structures together defining a first spectral signature. Each of the plurality of resonant structures includes a respective one of a frequency domain. The method also includes depositing a conductive material on at least one of the resonant structures to short the at least one of the resonant structures. The remainder of the plurality of resonant structures that are not shorted by the conductive material define a second spectral signature for the RFID transponder.

Embodiments of the invention include delay line circuitry that is integrated with an organic substrate. Organic dielectric material and a plurality of conductive layers form the organic substrate. The delay line circuitry includes a piezoelectric transducer to receive a guided electromagnetic wave signal and to generate an acoustic wave signal to be transmitted with an acoustic transmission medium. An acoustic reflector is communicatively coupled to the acoustic transmission medium. The acoustic reflector receives a plurality of acoustic wave signals from the acoustic transmission medium and reflects acoustic wave signals to the piezoelectric transducer using the acoustic transmission medium. The transducer converts the reflected acoustic signals into electromagnetic waves which are then transmitted back through the antenna and decoded by the reader.

A method and structure for a radio frequency identification (RFID) system including an RFID tag. The RFID tag can include a dampener configured to dampen a resonation of a resonator. Prior to dampening the resonation of the resonator using the dampener, the RFID tag may be configured to transmit a first response signal from a transmit antenna. Subsequent to dampening of the resonation of the resonator using the dampener, the RFID tag may be configured to transmit a second response signal that is different from the first response signal. The dampener may include a chemical agent or a fusible link.

One embodiment is a flat card that includes an electrically non-conductive substrate and a plurality of electrical conductors disposed on a surface of the non-conductive substrate. The conductors are connected together to form patterns of conductive lines connected to conductive geometric shapes located at ends of the conductive lines. A switch is positioned between two of the conductive geometric shapes and switchable between an open state and a closed state.

A fluid treatment cartridge includes a housing having a fluid inlet and a fluid outlet with a treatment media contained within the housing. The fluid treatment cartridge includes a detection member comprising at least one closed electrically conductive loop having at least two spatially separate sections. Each of the sections generates a magnetic response when at least one section is electromagnetically excited. The magnetic response of each section is predetermined by the physical shape of the section and comprises at least one of a predetermined magnetic phase response and a predetermined magnetic amplitude response. The predetermined magnetic response of at least one other section of the closed electrically conductive loop corresponds to at least a one digit code.

The present invention relates to a set of security documents. Each security document within the set having an optical code, notably a barcode, which is neither connected nor coupled to any electronic chip that may be carried by the security document. The optical code on each security document within the set encodes the same information for the same optical reader. Each security document having different respective electromagnetic signature, these signatures being unique to each of the security documents.

The present invention relates to radio-frequency identification (RFID) tags that produce a unique radar signature by passive reflection of an electromagnetic signal. In particular, provided herein are frequency-, phase-, and/or amplitude-shift encoded RFID tags, and methods of use and manufacture thereof.

A chipless RFID transponder is disclosed. The transponder comprises an antenna and a plurality of resonant structures that together define a spectral signature of the RFID transponder. Each of the resonant structures comprises conductive portions separated by interstitial regions. A reversible photoconductive material is disposed in the interstitial regions of the resonant structures between the conductive portions. The photoconductive material is positioned so as to shift the spectral signature of the RFID when exposed to radiation.

A chipless RFID transponder is disclosed. The transponder comprises an antenna and a plurality of resonant structures that together define a spectral signature of the RFID transponder. Each of the resonant structures comprises conductive portions separated by interstitial regions. A reversible photoconductive material is disposed in the interstitial regions of the resonant structures between the conductive portions. The photoconductive material is positioned so as to shift the spectral signature of the RFID when exposed to radiation.