Ultrasonic Anemometer for the Measurement of Respiratory Flow in the Forced Oscillation Technique

In this paper it is proposed a method to the measurement of respiratory flow in the forced oscillations technique (FOT) using an ultrasonic anemometer. It is used the transit time method and the phase difference technique with the measurements of the phase angle between the signal at the transmission and at the receiver to detect changes in the transit time due to flow. The ultrasonic anemometer implementation is based on a microcontroller. The experimental results of the tests with the comparison among this flowmeter and a classical pneumotachometer used in the FOT for flow measurement will are presented.