A fibre optic Bragg grating strain sensor for monitoring ventilatory movements

A fibre optic Bragg grating sensor to measure the strain in the chest of patients is described. The sensor provides a new method to measure ventilatory movements and it can also determine the respiratory frequency spectrum. The apparatus uses a fixed optical filter reference scheme to reduce the overall cost and is able to detect respiratory movements with frequency components up to 10 Hz. Ventilatory signals were acquired from slow breathing, with 500 ml inspiration volume, to fast, with a reduced volume of 60 ml, respiration. The sensor described here can be used to trigger the pulse burst of electrically assisted ventilation processes or to monitor high frequency oscillatory ventilation.