Franz Dollinger

A wireless pressure measurement system using a SAW hybrid sensor

A pressure measuring system based on surface acoustic wave (SAW) sensors is presented. Since SAW sensors are powered by the energy of the RF field no battery is required, which is a major drawback of conventional microcontroller based telemetry systems. A successful combination of a SAW reflective delay line with a high-Q capacitive pressure sensor is shown. With a new way of matching the sensor impedance to the SAW reflector impedance both a high signal-to-noise ratio and a high signal dynamic are achieved which supports accurate signal evaluation. As an example of realization the prototype of a tyre pressure sensor unit is presented.

A wireless pressure-measurement system using a SAW hybrid sensor

A pressure-measurement system based on surface-acoustic-wave (SAW) sensors is presented in this paper. Since SAW sensors are powered by the energy of the RF field, no battery is required, which is a major drawback of conventional microcontroller-based telemetry systems. A successful combination of a SAW reflective delay line with a high-Q capacitive pressure sensor is shown, With a new way of matching the sensor impedance to the SAW reflector impedance, both a high signal-to-noise ratio and a high signal dynamic are achieved, which supports accurate signal evaluation. As an example of realization, the prototype of the pressure sensor unit is presented.

Optimized design and fabrication of a wireless pressure and temperature sensor unit based on SAW transponder technology

The optimized design and fabrication of a passive pressure and temperature sensor unit based on SAW transponder technology fully meeting the restrictions of the European ISM RF band at 433.92 MHz is presented. The sensor unit consists of a reflective SAW delay line which is used as temperature sensor and transponder, and a capacitive pressure sensor. With a special arrangement of the impedance loaded splitfinger interdigital transducer, and the reference reflectors on the SAW substrate, a temperature corrected evaluation of the pressure signal is enabled. Due to the small dimensions and cost-effective design of the sensor unit, the utilization as a tire pressure sensor is proposed. A prototype of the SAW delay line and the micromachined pressure sensor is demonstrated.

Sensors reveal the secrets of car tyres

Modern cars include sophisticated electronics such as anti-blocking braking systems and electronic stability programmes. These systems rely on sensors to monitor the rotational speed of wheels. The sensors have to be built from strong materials to resist the forces that act on them. The data have to be processed using very fast and complex algorithms. It would be better if sensors could be placed in the tyres themselves. Researchers at the Technical University of Darmstadt have used sensors embedded in tyres to measure the dynamic deformation of rolling tyres on test benches. The deformation signal is related to the friction coefficient, allowing information to be obtained on the maximum force that can be transmitted between the tyre and road. Sensors in tyres must be able to withstand mechanical and thermal stresses encountered during driving and tyre manufacture. A system based on surface acoustic wave components has been developed to provide an electrical connection between the tyre and on-board electronics.

Reifenzustandsüberwachung — OFW-Funksensorik für den „intelligenten” Reifen

ZusammenfassungMit der Realisierung eines „intelligenten Reifens”, der ständig Informationen über seinen aktuellen Zustand an ein Kontrollsystem weitergibt, wird die Sicherheit im Auto erhöht. Das vorgestellte Reifendruck- und Temperaturmesssystem basiert auf der Anwendung von Oberflächenwellen (OFW)-Sensoren. Da OFW-Sensoren durch das Hochfrequenzfeld mit Energie versorgt werden, wird keine Batterie im Reifen benötigt. Ein Prototyp eines Reifendruck- und Temperatursensors mit einer typischen Druckgenauigkeit von ± 15 kPa und einer Höchsttemperatur von 130° C wird vorgestellt.AbstractWith the realization of a “smart tire”, capable of continuously transmitting information about its actual state, increased safety for passengers is achieved. The presented tire pressure and temperature measuring system is based on the application of surface acoustic wave (SAW) sensors. Since SAW sensors are powered by the energy of the RF field no battery is required inside the tire. The prototype of a tire pressure and temperature sensor featuring a typical pressure accuracy of ± 15 kPa and a heat stability up to 130° C is presented.

A wireless pressure-measurement system based on SAW transponder technique

A hybrid sensor system for tire pressure measurements is presented. We use a combination of a conventional capacitive pressure sensor together with a passive SAW transponder to build an impedance loaded reflective delay line which can be read out wirelessly. The sensor system together with a transceiver unit achieved a pressure resolution of at least /spl plusmn/ 0.15 kPa within a measurement range of 100 to 400 kPa.