DESIGN AND INVESTIGATION OF MICROMECHANICAL BRIDGE STRUCTURES FOR AN OPTICAL PRESSURE SENSOR WITH TEMPERATURE COMPENSATION

For fibre-optical sensor systems, a frequency-encoded sensor signal is of great interest due to its immunity against attenuation effects alo ng the fibre-optic transmission line. A possible approach for such sen sors is the use of silicon micromechanical bridges with optothermal ex citation and an interferometric measuring technique. A problem with su ch sensors is the cross-sensitivity to other parameters, especially to temperature. We have designed and realized a structure with two reson ant bridges made of silicon nitride to allow temperature compensation of a pressure measurement. By this method it is possible to reduce the temperature dependence of the pressure sensor to less than 1% within the temperature range used.