How to make your own Ventilator
Due to COVID-19 pandemic (Coronavirus) there is a huge lack of Medical Ventilators all around the world. Currently there are not enough Medical ventilators to support the large numbers of projected virus outbreaks in the population that are going to need access to a medical ventilator. Most cities and countries just don't have access to more units and Professional Medical Ventilators have a high price, that's not easy to buy in the hundreds and quickly.
Our goal was to create a Homemade Medical Ventilator from readily available materials that can be purchased online. This would be very cheap, and quick to put together, and for a fraction of the price. Whilst you may think its not a viable option to make a home made Ventilator read this article. "A Chinese boy was kept alive for 5 years using a home made Ventilator" Read here. When you read this amazing story you quickly realize that a homemade Ventilator is not as crazy as it sounds.
Legal notice: Firgelli does not accept any responsibility. Make it and use it on your own risk. We are publishing the idea as a backup for desperate times, such as if you are kicked out of the hospital or you know that the hospital has no more Ventilators left for use.
Homemade Medical Ventilator Theory
The principle behind a medical Ventilator is to put oxygen into the lungs and then extract Air from the lungs in a repeatable way that reproduces a natural breathing pattern. In a situation where someone has Breathing issues such as pneumonia, then the patient is not able to breath on their own and instead they need a machine to do the breathing for them.
The simplest mechanical device we could devise to assist a person’s breathing would be a hand-driven pump that is fitted to the person’s mouth and nose using a mask. The mask would require a one-way valve arrangement to cause air to flow from the device into the lungs when the device is compressed, and out from the lungs to the atmosphere as the device is expanded.
In our Actuator driven Medical Ventilator, a Linear Actuator is used to compress the air bag and when it is retracted the expansion of the bag exhales the air from the patients lungs. A Linear Actuator would simply compress a medical Ventilator bag at the correct frequency required by the patient. The Linear Actuator would be connected to an Arduino Board which would allow you to control the speed. Our Linear Actuators can be driven at 100% duty cycle so that the Home made Ventilator can run continuously, as would be required for the patient anyway.
Supplies required to make a DIY Ventilator:
- Bag valve mask. Readily available on Amazon these are already made for manual ventilation operation. They also have all the valves required and have a plug for an oxygen supply if required and only cost around $40
- Linear Actuator - we recommend a 4" Stroke Premium Electric Linear Actuator
- 12V power supply
- Arduino controller - micro-controller. This device is what you use to program the actuator to go in and out at a set speed.
To understand how to use an Arduino to control the 12V Actuator which compresses the Medical ventilator bag we created a blog post on how to run an Actuator using an Arduino here
Firstly the principle behind this concept is that the Bag valve mask is what puts air into the patient. Typically these valve masks are hand operated, but you can realistically only operate them for so long before your hand gets very tired. In addition the frequency needs to quite consistent for the patient to get the real benefit. The principle behind using an Electric Linear Actuator is that the Actuator will do all the bag squeezing for you and the controller simply sets the speed. We suggest making a Box to house the Linear Actuator and bag valve mask. Set the Linear Actuator at full extended stroke when the vale bag is fully compressed, and when the Actuator is retracted the bag will open up fully.
Ventilator Pressure setting
Medical Ventilators have different sensors that they use to control the flow of oxygen in the patient. One of these is a pressure sensor. To take the homemade Ventilator to the next level you could install a pressure sensor that the Arduino controller can also read and use to create a Air flow map that correctly matches how a patient needs to breath normally. Using the feedback from the pressure sensor it would be possible to adjust the Actuator speed to maintain the correct air pressure required. The curve above would help achieve these results.