Balloon Catheter with Integrated Airflow Sensor for Respiration Measurement Inside Lung Airway

Respiratory diseases such as chronic obstructive pulmonary disease (COPD) remain a leading cause of death worldwide, yet current clinical tools lack the ability to accurately quantify airflow parameters within specific lesion sites in the lungs. To address this need, we developed a balloon catheter sensor system capable of measuring respiration directly within the lung airways. A micro-electro mechanical systems (MEMS)-based thermal sensor was fabricated on a thin, flexible polyimide film and integrated into the catheter using its natural by-design buckling behavior. The balloon structure enabled airflow rate measurement independent of airway diameter, enhancing versatility. With an outer diameter of 4.0 mm, the catheter could be easily inserted into lung airways up to the 3<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> branch, which typically measures 5.6 mm in healthy adults. Real-time inhalation and exhalation airflow measurements were successfully demonstrated using an artificial ventilator model.