Development of sensor-probe system with function of measuring flow and pressure for evaluating breathing property at airway in lungs

We propose a sensor-probe system for evaluating local airway resistance in the lungs. The system consists of a micro-machined thermal-flow sensor, based on the hot-wire airflow-meter principle, fabricated on a flexible substrate consisting of Cu foil and polyimide film and a commercially available Si pressure sensor. We inserted the system into a tube with a 5.0-mm inner diameter to evaluate its detection properties under a steady-flow of up to 6.0 L/m. The flow velocity vs. sensor output and pressure vs. tube length were successfully obtained. We then applied the system for reciprocating airflow measurement. A flow of 30 cc at 0.5 Hz generated with an artificial ventilator was used to imitate the breathing of a small animal, and we confirmed that the system successfully detected both flow and pressure change generated in the tube.