We wanted to give a special acknowledgement to another non-profit team that is working on a low-cost ventilator, Respiraworks. Respiraworks is a talented group of engineers and designers who started work on a low-cost ventilator design in March 2020, just a few weeks before Project RED. We exchanged ideas and learned a lot through discussions with Respiraworks, and in fact a key piece of technology we use in the RED ventilator was created by Respiraworks, the “pinch-valve” actuator. Early in the project, we explored several different approaches for controlling expiratory flow and maintaining PEEP pressure, but found various tradeoffs and limitations with the methods we tried. Respiraworks came up with a clever and cost-effective solution to this problem with their custom pinch-valve, based on a low-cost stepper motor typically used for 3D printing and CNC applications. Given that their project is open-source, they were happy to share the design with us, which we then adapted for the RED design. Two images of the pinch valve are shown below: the first is the original pinch valve designed by Respiraworks, and the second is the design with some changes made to adapt it to the RED design.
We encourage you to check out Respiraworks’ project in addition to Project RED. The design principle of their ventilator is similar to ours, though there are various differences in the implementation details and licensing approach. We believe that many different and parallel efforts will be needed to increase global supply of ventilators to where it needs to be. Kudos to Respiraworks for their ingenuity and spirit of engineering collaboration!