Fiber-Optic EFPI Pressure Sensors for In Vivo Urodynamic Analysis

A fiber optic sensing system for pressure measurement in invasive urodynamics is presented and experimentally validated. Probes are based on extrinsic Fabry-Perot interferometry (EFPI) principle, with an all-glass biocompatible design having 0.2-mm thickness. Pressure sensitivity of 1.0-1.6 nm/kPa with high stability and reduced thermal sensitivity has been achieved, leading to 0.3-cmH₂O pressure accuracy. The EFPI probes have been embedded in medical catheters with 4F size for dual bladder and abdominal pressure measurement throughout the full course of a urodynamic analysis. Pressure traces have been compared with a PICO2000 urodynamic instrument, showing improved accuracy and higher responsivity to local pressure variations. Tests have been carried out in vivo on seven patients; the main highlights are reported, showing the premises for an EFPI-based diagnostic tool.