Toward Accessible Lung Diagnostics: Design and Development of a Portable Spirometer with IoT-Based Flow Sensor Display

Chronic Obstructive Pulmonary Disease (COPD) is one of the most prevalent respiratory disorders worldwide, yet access to spirometry for early diagnosis remains limited in community and low-resource settings due to the high cost and immobility of conventional devices. This study addresses this gap by designing and developing a portable, IoT-enabled spirometer capable of performing remote lung function examinations, particularly for COPD and asthma patients. The device measures the volume of air entering and leaving the lungs using an AICHI G1/2-inch turbine-type flow sensor, controlled by an ESP32 microcontroller, to obtain FVC (Forced Vital Capacity), FEV1 (Forced Expiratory Volume in 1 second), and the FEV1/FVC ratio. Unlike previous portable spirometer designs, the proposed system transmits measurement data in real time to an Android application developed with MIT App Inventor via Wi-Fi, and enables export of patient records in PDF format. The device accuracy was validated on 60 participants: the FVC error rate ranged from -7.7% to 7.4% (mean absolute error 4.2%), while FEV1 error varied from -59% to 23.4%, with the higher variability attributed to patient effort variability and sensor calibration tolerances. The FEV1/FVC ratio showed generally minimal error. These results demonstrate the feasibility of the proposed system as an accessible and practical tool for lung function assessment and early detection of pulmonary disorders.