OpenVent – 3D printable BVM Ventilator, Design B1, Geared Pliers

During the Corona (COVID-19) pandemic it became obvious that a lack of medical equipment can cause a severe impact. Often, also simple equipment and designs can be helpful as long as no professional equipment is available.

This repository contains generic information about an open-source ventilator device. Main purpose of this project is to build a ventilator when no professional and medical equipment is available. Easy to assemble and available components are used with a clear focus on simplicity, availability and scalability.

This project started as part of the hackathon #WirvsVirus of the German government.

Please check the full disclaimer as well before proceeding:

The material and documentation here is provided with no warranties explicit or implied.

No material on this site is intended to provide medical advice. All designs are intended for investigational use only.

This site does not represent any official policies or procedures.

The project is provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement.

In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

Only use this repository, designs, documentation or any provided information if you accept the above disclaimer.

Additional discussion, documentation, source code, electronics and sensor design is available at

GitHub(
https://github.com/mhollfelder/openvent

) and YouTube(
https://www.youtube.com/channel/UCw9h6QsYEKY2sfZIYBNuHvw

).

This thing represents a very different design versus our initial prototype. Extensions and upgrades will be posted here as well. Please check those, too.

General concept

An AMBU-bag is used as pressure reservoir. It already features an O2 inlet (O2 concentration is crucial for patients with acute respiratory syndrome) and several safety features including e.g. overpressure and bypass valves. Being standard for emergency help, these bags are available at substantial volumes.

A motorized and microcontroller+sensor controlled setup squeezes the bag at the right pattern, supporting assist-, pressure-, volume- and flow-control ventilation and exhaled gas measurements and filters.

All is based on open source and commonly accessible parts; especially for the mechanics the objective is to be scaleable in production and hence fully 3D-printable. Only the motor and it’s screws as well the belt is not printed. Standard stepper motors such as Nema17 or 23 are proposed.

Electronics, sensors and software are covered in our GitHub pages.

Experiences

This design has been designed, built and tested. It’s robustness has been confirmed. The simplicity of the design and excellent printability are tempting. All parts can print in a single print job on machines with about than 20cmx20cm build area in less than 12 hours at 0.2mm layer resolution. Robustness has higher priority than printing time. However, such high resolution is not required for the design, hence additional speed-up potential is given, as long as good layer adhesion is not compromised.

On the down-side, this design is slightly more complex in assembly (glue required) and lubrication may be beneficial for reduction of friction losses (it also works without). Endurance testing and optimization of the gear ratio is pending. More detailed discussions on our GitHub pages.