Development of Catheter-type Flow Sensor for Trans-bronchial Measurements

摘要

We developed a novel catheter-type thermal flow sensor as a tool for trans-bronchial measurements. The sensor is mounted inside a tube and is used as one of the treatment tools of a bronchoscope. The external diameter of the tube is less than a few mm, and, therefore, the sensor can evaluate the flow characteristics in the small bronchus region. The relationship between the input power of the sensor and the flow-rate obeyed the equation of King under both forward and reverse flow conditions. The sensor output dependency on ambient temperature was also studied, and the graph obtained at 39.2°C was used as the calibration curve in animal experiments. The sensor's characteristics under reciprocating flow were studied using a ventilator, and the sensor was able to measure reciprocating flow at 2.0 Hz. Finally, the characteristics of aspirated and inspired air in the air passage of a rat were measured.