Static and dynamic performance of a venturi airflow sensor

Venturi-meters have received limited application to the measurement of human airflow. A 3-D printed Venturi airflow sensor (fV) was integrated to a differential pressure sensor for the purpose to document signal quality, dynamic performance during instantaneous flow, and airflow analysis with subsequent calibration for volume measurement. In addition, we assessed these results for potential use in the measurement of human pulmonary ventilation. The fV was developed via drafting software program and 3-D printer (38 mm ID inlet, 12 mm ID constriction, and 23° conical transition sections). The fV was matched to a differential pressure transducer (0–7 kPa input per 0–10 VDC output). The fV was connected in series with a Pneumotachometer (fP) and Turbine airflow sensor (fT), with 1 m length tracheal tubing (ID: 35 mm), separating the devices. Airflow conditions were controlled by an industrial vacuum for constant flow with a manual-operated ball valve connected in series, and a criterion 3 L calibrated syringe for instantaneous flow. Repeated baseline data were collected for signal stability, and to identify the signal-to-noise ratio for signal quality. Airflow estimates and signal quality analysis was performed on repeated constant airflow conditions that spanned the transducer 0–10 VDC output. Repeated syringe manoeuvres that spanned the transducer 0–10 VDC output were used to determine the dynamic performance of the fV. A paired t-test revealed no statistical difference between fV and fP for signal quality across all airflow conditions (p = 0.2028). A paired t-test of dynamic performance data revealed no statistical significance between response times for the fV Vs fP. A calibration method was tested for validation in volume measurements, which resulted in a mean estimate = 3.032 L; CV = 1.14%; n = 83. The fV is easily manufactured with a durable and simple design, making its potential use for ventilation measurement an affordable and reliable technology. These findings provide a reasonable basis to pursue fV technology in applied validation studies, such as inspired and expired ventilation measurement.