DESIGN AND DEVELOPMENT OF AN OPEN-SOURCE HARDWARE DIGITAL OXYGEN FLOW CONTROLLER FOR RESPIRATORY THERAPY

Abstract

Conventional oxygen flow controllers rely on manual knob adjustment and separate devices for neonatal and adult patients, increasing equipment costs, complicating clinical workflows, and adding maintenance burdens. To address these challenges, we developed a unified, low-cost, open-source digital oxygen flow controller capable of regulating oxygen delivery from 0.1 to 15 LPM. The system is constructed using readily available components, including a stepper motor, a flow sensor, and a microcontroller, and employs a Proportional–Integral–Derivative (PID) feedback control algorithm to achieve precise real-time flow regulation. The open-source hardware and firmware architecture enhances transparency and reproducibility while providing a flexible platform for future research involving closed-loop feedback systems, in which oxygen flow rates can be automatically adjusted in response to patient-specific physiological signals. Experimental validation demonstrated robust performance across the full therapeutic range. For flow rates between 1 and 15 LPM, delivered flows closely matched setpoints with low variability, and Bland–Altman analysis indicated a consistent bias of 0.02 LPM with narrow limits of agreement. In the neonatal range (0.1–1.0 LPM), measurement deviations were generally below 8%. These findings confirm that a simple, open-source, component-based digital design can deliver accurate and predictable oxygen flow control for both neonatal and adult respiratory therapy, offering a cost-effective and extensible foundation for advanced feedback-controlled oxygen delivery and future integration with patient monitoring and adaptive respiratory support systems.