Abstract: An apparatus and method for distinguishing between sensors that are to be wirelessly detected is provided. An interrogator device uses different, distinct time delays in the sensing signals when interrogating the sensors. The sensors are provided with different distinct pedestal delays. Sensors that have the same pedestal delay as the delay selected by the interrogator are detected by the interrogator whereas other sensors with different pedestal delays are not sensed. Multiple sensors with a given pedestal delay are provided with different codes so as to be distinguished from one another by the interrogator. The interrogator uses a signal that is transmitted to the sensor and returned by the sensor for combination and integration with the reference signal that has been processed by a function. The sensor may be a surface acoustic wave device having a differential impulse response with a power spectral density consisting of lobes.

Abstract: An acoustic wave sensor array device is provided for the detection, identification, and quantification of chemicals and biological elements dispersed in fluids. The sensor array device is capable of the simultaneous characterization of a fluid for multiple analytes of interest. A substrate has a plurality of channels formed therein and a sensor material layer applied in a bottom of the channels. The sensor material layer has a shear acoustic wave speed lower than a shear acoustic wave speed in said substrate. The channels may have the same material in each channel or different materials in at least two of the channels. A surface acoustic wave transducer and at least one surface acoustic wave reflector, or at least two transducers is formed on a surface of the substrate opposite the channels at a portion of the substrate that is thinned by the channels, so that the acoustic tracks of the surface acoustic wave device extend along the channels.

Abstract: A temperature measurement system is characterized by at least one passive surface acoustic wave (SAW) temperature sensor. The sensor includes at least one piezoelectric substrate having an interdigital SAW transducer disposed upon the piezoelectric substrate for conversion of an RF signal into an acoustic wave and vice versa. At least three additional SAW elements are also disposed on the substrates in a manner such that they define two acoustic propagation paths that are non-parallel relative to the crystal axes of the substrates, and such that the temperature coefficients of delay in the two tracks differ. The SAW elements receive a signal from the SAW transducer and produce response signals. The response signals combine to produce a signal with a power spectral density such that the integrated power within each of two specified portions of the spectrum provides an indicator of the temperature.

Abstract: A hydrogen detecting system is characterized by a passive surface acoustic wave (SAW) sensor. The sensor includes a piezoelectric substrate having a self assembled monolayer arranged on at least a portion of the substrate to create a hydrophobic surface. A palladium nanocluster thin film is deposited on the monolayer and an interdigital SAW transducer is disposed upon the piezoelectric substrate for conversion of an RF signal into an acoustic wave and vice versa. At least one additional SAW element is also disposed on the substrate and spaced from the SAW transducer. The SAW element receives a signal from the SAW transducer and produces a response signal. The response signal is modified by the palladium nanocluster film due to a change in conductivity of the palladium nanocluster film upon exposure to hydrogen. This change in the response signal is measured by an interrogator, and yields a measure of the hydrogen concentration to which the sensor was exposed.

Abstract: A method and apparatus for wireless measurement of the temperature in curing concrete is characterized by the use of a plurality of surface acoustic wave temperature sensors embedded in the concrete. An interrogation signal from an external transceiver system is modified by the sensors in accordance with the temperature of the concrete adjacent to the sensors. The return signals from the sensors are processed in a correlation device to identify each signal as originating from a specific sensor. A microprocessor calculates the maturity of the concrete based on the data received from the sensors as well as data input corresponding to the type of concrete. The maturity data is used to analyze the strength and integrity of the concrete structure being built.