Authors:

Abstract

Pharmaceutical therapy for certain respiratory diseases involves delivering aerosolized drugs directly to the respiratory tract through inhalation with nebulizers. This research is focused on designing an automated jet nebulizer that possesses the capability of dynamic flow regulation. The proposed nebulizer is composed of two modes, namely, the Compressed Air mode and the Oxygen Therapy mode. The automated triggering from one mode to another will be dependent upon the percentage of oxygen saturation of the patient, monitored from the SpO2 sensor. The compressed airflow will be delivered to the patient according to his or her volumetric breathing rate, derived with the aid of a temperature sensor-based algorithm. The compressor circuitry is incorporated with a PID control unit, which is a novel feature that acts as feedback as well as a safety mechanism in ensuring that the patient receives compressed air as per the flow rate decided by the system. At the end of the drug delivery, if the liquid level sensor detects the absence of medication within the nebulizer chamber, the nebulization process will be terminated. The results obtained from simulations showed that the PID unit functioned smoothly, with less overshoot and response time. Thus, the dynamic regulation of the motor speed with respect to the volumetric breathing rates was accomplished. A laminar flow was obtained from the outlet of the compressor towards the nebulizer tubing, and a turbulent flow was obtained within the chamber, as expected. No excessive turbulent flows or rotational flow patterns were detected. 

Keywords: Inhalation therapy, jet nebulizer, proportional integral derivative controller