The fibre Fabry Perot sensor. A long-term manometry sensor for quantitative intraluminal pressure measurement of the gastrointestinal tract.

Sensor dislocation of water perfused side-hole manometry catheters during longer periods of examination, as well as heavy expenditure on equipment and personal, are disadvantages of perfusion manometry. Such catheters have contributed substantially to the attempt to become independent of water as a transmitter medium in manometric pressure sensors for the upper gastrointestinal tract. Using the principle of the mirror interferometer of Fabry and Perot, we have developed and manufactured a fibre-optic Fabry Perot Sensor (FFP) which records local asymmetric pressure with constant sensitivity over the sensor surface area of 40 mm length. The FFP signal was compared with the pressure measured with a conventional four-side-hole perfusion catheter. The signal corresponding to long-term basal pressure of the lower oesophageal sphincter (LOS) varied over a normal range, and the signal presenting the pressure in the tubular oesophagus had a normal range determined from 15 healthy volunteers. Due to the phase modulation of its laser, the FFP is nearly independent of substantial artefacts.