ABSTRACT

Resonator sensors are mechanical structures driven at their resonant frequency. It is arranged in the design of the sensor structure that the parameter to be measured alters the resonant frequency or the frequency spectrum or both. This chapter describes some of the structures that have been produced in prototype form or as a commercial product. An invasive liquid density sensor is available from Schlumberger using tuning fork-type tines. A number of the sensors have piezoelectric drive and sense transducers. Commonly, fabrication of these components is by some form of thick film process. A detector unit must measure some parameter that indicates the status of the sensor. Sensors have been developed using wires made from the metals tungsten, indium and high tensile steel as well as alloys such as Elinvar. A commercial pressure sensor using the double tuning fork structure is available from Yokogawa of Japan.