VU engineers and VUMC doctors team up for open-source ventilator design

As COVID-19 continues to push unprecedented challenges on medical communities, one of the most pressing threats for hospital staff across the country is a dwindling supply of ventilators.

Now, an interdisciplinary team of Vanderbilt University and Vanderbilt University Medical Center faculty is taking on the challenge by way of a fabricated, open-source ventilator design.

Led on the Vanderbilt side by engineers Kevin Galloway, research assistant professor of mechanical engineering and director of making at the Wond’ry, and Robert Webster, Richard A. Schroeder Professor of Mechanical Engineering, the team is currently on “version two” of the ventilator prototype and hopes to soon move into the final prototype phase before manufacturing.

“Maker communities around the globe are stepping up to address the pressing medical challenges presented by COVID-19, such as the need for personal protection equipment like face masks,” said Galloway. “In conversation with Bob Webster and colleagues at the Medical Center, we discussed how we can leverage our expertise to tackle this one issue which resonated most strongly for us.”

After an initial conversation with VUMC physician Duke Herrell discussing the threat posed by a lack of respiratory support equipment, Webster reached out to Galloway about a design he had already been toying with in his home garage as well as a process to figure out the signature difficulty in making a ventilator: replicating the precise force of the hand involved in squeezing a manual bag.

In the first prototype, Galloway wrapped nylon webbing around an Ambu bag and attached it to the crank arm of a windshield wiper motor to apply the repetitive squeezing force. While the design worked, they still needed a cleaner design where the amount of squeeze (known as tidal volume) could be controlled more precisely.

From left Fabien Maldonado, MD, Michael Lester, MD, and Robert Webster, Ph.D., help postdoc Joshua Gafford make adjustments to a homemade ventilator in the CELA Lab MRBIV third floor. Engineering professor Robert Webster and postdoc Joshua Gafford created this homemade open-source ventilator design in the hope that it can be made en masse to help relieve the shortage of ventilators due to COVID-19. (Vanderbilt University)

Inspired by the Scotch Yoke Mechanism, Galloway built his second (and latest) prototype in under three hours using the same motor, drawer glides, and plywood — materials and tools that could be found almost anywhere in the world — while Webster and his colleagues added sensors and controls to the design to improve the safety and tune the “in-and-out” ratio to match normal breathing.

“This was the result of a lot of conversations with doctors where it became clear that a pressure sensor with an alarm on it for too-high or too-low pressure was essential to the design,” noted Webster. “This is something we would not have known without having many Vanderbilt physicians involved in the project including Fabien Maldonado, Erin Gillespie, Matthew Bacchetta, Michael Lester, Arna Banerjee, Craig Rooks, Ph.D. student Max Emerson, who did the design of the sensor, and postdoctoral fellow Joshua Gafford, who designed the controls.”

The near-term goal for the team is to take the feedback from the ongoing ventilator tests with VUMC doctors and incorporate it into “version three,” which they feel will be extremely close to a design that the doctors would feel comfortable using on a patient in an emergency.

According to Webster, they are getting ready to be able to quickly produce about 100 ventilators in the next week – should the need arise.

The long-term goal? “Make the design publicly available so that anyone can replicate it,” said Galloway.