A transistors-based, bidirectional flowmeter for neonatal ventilation: design and experimental characterization.

Area of Science:

• Biomedical Engineering
• Medical Devices
• Sensor Technology

Background:

• Neonatal artificial ventilation requires precise monitoring of airflow.
• Existing flowmeters can be costly or unsuitable for single-patient circuits.
• Bidirectional flow measurement is crucial for accurate ventilation assessment.

Purpose of the Study:

• To develop and characterize a low-cost, bidirectional flowmeter for neonatal artificial ventilation.
• To evaluate the performance of the flowmeter in mono-patient breathing circuits.
• To assess the impact of pipe diameter and collector current on sensor performance.

Main Methods:

• Utilized two bipolar junction transistors as hot-body sensors.
• Employed Joule heating and convective heat transfer for flow sensing.
• Conducted static calibration across various flow rates, pipe diameters (10 mm and 30 mm), and collector currents (100-500 mA).

Main Results:

• The 10 mm diameter configuration at 500 mA collector current offered highest sensitivity (763 mV/L·min⁻¹) and minimal dead space (2 mL).
• The 30 mm diameter configuration extended the measurement range (up to ±6 L·min⁻¹) and improved discrimination threshold (<0.1 L·min⁻¹) and response symmetry.
• The flowmeter demonstrated effective bidirectional measurement and direction discrimination.

Conclusions:

• The developed flowmeter is a cost-effective solution for neonatal ventilation.
• Its design offers a favorable balance of sensitivity, dead space, measurement range, and accuracy.
• The sensor is suitable for application in mono-patient breathing circuits for neonatal respiratory support.