OpenVent - 3D printable BVM Ventilator, Design B2, Cabled Pliers

thingiverse

During the COVID-19 pandemic, it became glaringly apparent that a lack of medical equipment can have a devastating impact. Often, even simple equipment and designs can be a game-changer as long as professional equipment is not available. This repository contains essential information about **an open-source ventilator device**. The primary purpose of this project is to build a ventilator when no professional or medical equipment is readily available. Easy-to-assemble and accessible components are used with a clear focus on simplicity, availability, and scalability. This project started as part of the hackathon #WirVsVirus organized by the German government and has continued since, also integrated into this and other platforms. Please review the full disclaimer carefully before proceeding: The material and documentation provided here come with no warranties explicit or implied. No content on this site is intended to offer medical advice. All designs are intended for investigational use only. This site does not represent any official policies or procedures. The project is offered "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 provided information if you accept the above disclaimer. Additional discussion, documentation, source code, electronics, and sensor design are available at **GitHub** (https://github.com/mhollfelder/openvent) and **YouTube** (https://www.youtube.com/channel/UCw9h6QsYEKY2sfZIYBNuHvw). This variant represents a modification of our second design with two sliding pliers, actuated this time by a belt/cable instead of a direct gear. Extensions and upgrades will be posted here as well. Please check those too. **General concept** An AMBU-bag is used as pressure reservoir. It features an O2 inlet (O2 concentration is crucial for patients with acute respiratory syndrome) and several safety features, including overpressure and bypass valves. Being standard for emergency help, these bags are available in 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 scalable in production and hence fully 3D-printable. Only the motor and its screws as well as the belt are 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. Its robustness has been confirmed too. Still, it is a simple, well-printable design. However, the additional base-layer for the belt mechanics causes the print typically to be split in two sequential print jobs on machines with about than 20cmx20cm build area and a print time of closer to 18 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. The tricky part of this design is the assembly, in particular to ensure equal tension of the belt for both pliers at the two sides. Es with the previous (B1) design, standard cyano glue is required to connect top-and-bottom part of the sliders and lubrication may become beneficial for reduction of friction losses (it also works without). Endurance testing and optimization of the gear ratio is pending. More detailed discussions to follow on our GitHub pages.