Electronic Thesis and Dissertation Repository

Thesis Format



Master of Engineering Science


Electrical and Computer Engineering


Trejos, Ana L.

2nd Supervisor

DeGroot, Christopher



Respiratory illness and diseases are ranked five out of the thirty most common causes of death worldwide. Thus, the use of a ventilator becomes a must for assisting patients suffering from respiratory disorders. The COVID-19 outbreak has aggravated the situation. Difficulty breathing is one of the most common symptoms of COVID. Out of 20% symptomatic COVID patients that require hospitalization, about 5% ended up in the ICU (Intensive Care Unit), most of them requiring ventilation. The world saw a scarcity of ventilators when COVID was at its first peak, with manually ventilating patients using an ambu bag being the only option left. The lack of ventilators was a struggle for every country around the world. One of the leading factors for the shortage of ventilators has been due to their cost. This situation affected developing and under-developed countries the most.

The objective of this project as a whole is to develop a low-cost emergency use ventilator device that can be readily mass-produced and used during an emergency such as COVID. This thesis describes the design, development, data collection, analysis, and validation of the control system of an open-source mechanical ventilator using a bag valve mask (BVM) and a microcontroller. Airflow data were collected from a range of different settings for compliance and resistance of lungs. These data were further assessed and compared to the input data.

A list of requirements and specifications needed for the design of an emergency respirator was made after consulting with expert respiratory therapists and clinicians. A prototype was built based on the first version of the mechanical ventilator developed at Robarts. The prototype was tested for different settings of Tidal Volume (Vt), Breaths per Minute (BPM) and I:E (Inspiration: ii

Expiration) ratio. Safety alarms and flow sensors were added to the existing prototype to increase the intelligence of the controller, for real-time data collection and to check the accuracy of the device. The device monitors the inspiratory and expiratory pressure, Vt, BPM, I:E ratio, cycle (for the motor) and peak pressure.

This work suggests that there is a potential to produce a commercialized regulatory approved version of an open-source ventilator system so that it can be easily accessible to medical centers all around the world when an outbreak such as COVID occurs again. However, more research is necessary in order to add more functionality such as multiple modes of ventilation, measurement of plateau pressure, monitoring and measurement of Fi𝑂2 and improving the specificity of the ventilation model.

Keywords: Mechanical Ventilation, Respiratory Diseases, COVID-19, Arduino Due

Summary for Lay Audience

Respiratory Diseases are most common causes of death worldwide. In extreme cases, the use of ventilators becomes a necessity for assisting patients suffering from respiratory diseases. Mechanical ventilators are devices that assist a patient to breathe when they are having difficulties breathing on their own. In the recent times, COVID-19 outbreak caused scarcity of the ventilators in many developing and under-developed countries. One of the most common symptoms of COVID-19 is difficulty in breathing. Out of 20% COVID-19 patients, about 5 % end up in ICU and most of them require ventilation.

The objective of this project as a whole is to develop open-source low-cost ventilators. An open-source ventilator is made using free licensed design and freely available components. These types of ventilators can be easily mass-produced since they are low-cost devices and used during emergency situations. This thesis describes the design and development of the control system of open-source low-cost ventilators using a mask that is connected to squeezable bag to help the patient breath in and breath out. The squeezing of the bag is controlled by simplified computer device. Several experiments were conducted to check the safety and operation of the device.