Preliminary evaluation of a fiber-optic sensor for flow measurements in pulmonary ventilators

A novel optical fiber air flow sensor was developed for monitoring flow rates supplied by infant ventilators. The device is based on a fiber optic sensing technique and overcomes some important shortcomings of biomedical applications, such as electromagnetic interference and possible electrical hazard. The sensing principle is based on measuring the displacement of an emitting optical fiber cantilever by means of a photodiode linear array: the detection of the illumination pattern makes the developed system less sensitive to light intensity source variations than intensity-based sensors. A preliminary evaluation of the relationship between displacement and flow rate is theoretically and experimentally conducted, as well as a measurement range up to 3.00·10^-4 m³/s (18.0 l/min) has been verified, in accordance to the flow range usual for tidal breathing of infants.