Detection of kinetic heartbeat signals from airflow at mouth by catheter flow sensor with temperature compensation

To precisely evaluate kinetic heartbeat signals from the airflow at the mouth, we newly integrated a temperature sensor onto a catheter flow sensor to compensate for the temperature change between inspiration and expiration. The catheter flow sensor was fabricated by MEMS technology, and the variation of sensor outputs under the temperature change was successfully suppressed to less than 2.5%. Then the sensor was directly inserted into the rat's airway, and the obtained waveform was analyzed by discrete Fourier transform. We consequently extracted kinetic heartbeat signals from the airflow.