Development of Catheter Flow Sensor for Breathing Measurements at Different Levels of Tracheobronchial Airway

We attempted to develop different sized catheter flow sensors for evaluating breathing characteristics at different levels of the tracheobronchial airway in a lung system. Two catheter flow sensors with 1.8 and 3.5 mm outer diameters were designed for measuring breathing characteristics in bronchus- and bronchiole- regions in the lung system, respectively. They were fabricated by using photolithography and heat shrinkable tube packaging processes. We experimentally investigated the fundamental sensor characteristic and found that the sensor output depended on the mean flow velocity. The developed catheter flow sensors also successfully detected the oscillating airflow produced by an artificial ventilator