Differentialin vivourodynamic measurement in a single thin catheter based on two optical fiber pressure sensors

Abstract

Urodynamic analysis is the predominant method for evaluating dysfunctions in the lower urinary tract. The exam measures the pressure during the filling and voiding process of the bladder and is mainly interested in the contraction of the bladder muscles. The data arising out of these pressure measurements enables the urologist to arrive at a precise diagnosis and prescribe an adequate treatment. A technique based on two optical fiber pressure and temperature sensors with a resolution of better than 0.1 cm H₂O (∼10 Pa), a stability better than 1 cm H₂O/hour, and a diameter of 0.2 mm in a miniature catheter with a diameter of only 5 Fr (1.67 mm), was used. This technique was tested in vivo on four patients with a real-time urodynamic measurement system. The optical system presented showed a very good correlation to two commercially available medical reference sensors. Furthermore, the optical urodynamic system demonstrated a higher dynamic and better sensitivity to detect small obstructions than both pre-existing medical systems currently in use in the urodynamic field.

Simultaneous Detection of Multiple Fiber-Optic Fabry–Perot Interferometry Sensors With Cepstrum-Division Multiplexing

“…In order to simulate the operation with standard off-the-shelf equipment, similar to FBG interrogation, it is assumed that the source is a light emitting diode (LED) with a flat-top spectrum with 80 nm bandwidth, while the spectrometer (SM) detector has 80 nm bandwidth (1520 -1600 nm). Some systems operate with a spectrometer as detector, usually integrating the amplitude over 16 bits (65536 levels) and the wavelength on a grid of 9 bits (512 points) over 80 nm; this parameters are the same of most lowcost FBG interrogators, such as the one proposed in [3], and are therefore applied in the following simulations. Fig.…”

“…A preliminary experimental validation is also included. (c) Parallel simultaneous interrogation of an EFPI array, fabricated on each tip; (d) the inset shows the typical design of an EFPI probe for pressure sensing [3][4][5].…”

“…These systems are based on a diaphragm, made with a glass fiber [3], flexible organic materials [4], metallic layer [5], graphene [6] or UV-mold [7]. FPI sensors are also established as sophisticated thermal sensors [8][9], thanks to their capability to operate at high temperature maintaining a linear calibration.…”

“…EFPI sensors are consistently finding application in pressure sensing [3][4][5][6][7]. These systems are based on a diaphragm, made with a glass fiber [3], flexible organic materials [4], metallic layer [5], graphene [6] or UV-mold [7].…”

“…Recent works have also been proposed for refractive index [11] and humidity sensors [12] based on FPI structures. FPI sensors are a consolidated technology in medical catheters for pressure sensing [3,13], thanks to their miniature sensing head and cabling, and improved accuracy over fiber Bragg grating (FBG) sensors. FPI sensor are also well established in oil and gas applications [1,8], whereas the capability to sustain very high temperature and pressure levels is a key asset.…”