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.

Abstract: A pressure and temperature sensor includes a sealed insulating package and an elastic, piezoelectric substrate deformably supported within the package. At least three surface-acoustic-wave resonators are affixed to a bottom of the substrate. A first and a second resonator are positioned in parallel relation along the substrate. A third resonator has a long axis nonparallel to the long axes of the first and the second resonator. The temperature coefficients of the first and second resonators are substantially equivalent; that of the third is different from those of the first and the second resonator, for permitting a temperature change to be sensed. Electrical connectors extend between the resonators to the outside of the package. A sensing system also includes an antenna for sending and receiving electromagnetic signals to and from the device.

Abstract: A pressure and temperature sensor includes a sealed insulating package and an elastic, piezoelectric substrate deformably supported within the package. At least three surface-acoustic-wave resonators are affixed to a bottom of the substrate. A first and a second resonator are positioned in parallel relation along the substrate. A third resonator has a long axis nonparallel to the long axes of the first and the second resonator. The temperature coefficients of the first and second resonators are substantially equivalent; that of the third is different from those of the first and the second resonator, for permitting a temperature change to be sensed. Electrical connectors extend between the resonators to the outside of the package. A sensing system also includes an antenna for sending and receiving electromagnetic signals to and from the device.