Biconically-tapered optical fiber probes for the measurement of esophageal pressure

A miniaturized optical fiber probe for measuring esophageal pressure, that makes use of biconically-tapered fibers, has been built and characterized. The functioning of this probe is based on the decrease in transmitted power in the fiber, when it is bent in its biconical part under the action of pressure. We made and tested several probes, using different fibers (monomode and few-modes) and different tapering values. Our best result was achieved with a probe which utilizes a biconical monomode fiber that has a waist diameter of 36 μm. The resolution obtained was 2 mm Hg in the range between 5 and 55 mm Hg.