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 when no professional equipment is available.
This documentation and repository contains information about an open-source ventilator device. Main purpose of this project is to generate ventilator design files and documentation for situations, when no professional and medical equipment can be obtained. Easy to assemble and available components are used with a clear focus on simplicity, availability and scalability, so local and short notice production is enabled wherever needed around the globe.
The material and documentation here is provided as open source 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), Thingiverse (https://www.thingiverse.com/search?q=OpenVent&type=things&sort=relevant) and YouTube (https://www.youtube.com/channel/UCw9h6QsYEKY2sfZIYBNuHvw)
What it does
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. Additionally provided design-files for 3D-printed adapters and valves also shall help to fill in gaps 'accessory' supply with professional equipment (secure, that all available equipment can always be used) and/or allow to reduce infection risk of medical personal (e.g. filters and UV lighting to exhaled air) and/or enable best use of professional equipment for critical cases (e.g. switch patient on recovery track to lower requirements open source ventilator). 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. Design findings and results are openly shared as part of the open source, so other teams can easily also build upon it.
How we built it
We started with study of medical requirements and assigned them to key blocks of a modular total system design, including mechanical block, motor and motor control block, sensor systems for pressure/flow/co2 and o2, main control unit, etc. These where followed in separate agile sub-tracks, with daily sprint sessions and using tools like slack, GitHub, discord,...
Challenges we ran into
Exemplary we describe the course of our mechanical subsystem. Meanwhile we have designed, tested and validated approx 5 different principle designs, not including variations, and chosen our two favorite platforms which now undergo further robustness and endurance testing, verification with medical experts and possibly minor optimizations for manufacturability, flexibility (eg. motor choices). Not all are fully documented on the named platforms yet, we have just recruited additional supporters for the documentation and working on it intensively to open the platform for further contributors, specifically for the main control system implementation, validation with medical, and optimization of the sensor and motor control sub-blocks. Detailed findings of the respective design steps are discussed on the thingiverse "OpenVent" and the GitHub channel.
Accomplishments that we're proud of
- systematic, yet fast design approach and true commitment to open source to enable the worldwide community to take advantage of it to limit the consequences of covid-19
- we have already arrived at a robust and validated mechanical design and will soon reach similar state for the sensor and motor subsystems. We have possibly the first design, that is truly easily repeatably scalable and globally transferrable though being completely 3D-printable, without need for special bolds, or other elements, except the motor itself, where the design supports a range of options both mechanically and electronically.
- we are in exchange (we are cautious of the valuable and scarce resource "doctors" and hence use it carefully) with medical experts and receive very positive feedback and confirmation of our assumptions and requirements.
The core team which started this project: Mahmoud Ismail Nico Kelling Daniel Gernert Alexander Maier Manuel Hollfelder
What we learned
despite initial skepticism if this could ever be actually used, positive feedback from experts strengthens our belief that this can save lives.
What's next for OpenVent open-source 3D printable ventilator
completion of algorithm design. validation of sensor subsystem. optimization of motor control subsystem. continuation of partnering with print-hub-networks/operators to secure fast availability to hospitals. documentation, documentation, documentation. test and validation of the complete system together with medical.
Try It out
ambu-bag, c/c++-controlsoftware, cad/cam/3d-print, co2-sensor, embeddedmcu-xmc/arduino, fully-3d-printed-mechanics, lcd-display-and-gui, nema-steppermotor, o2-sensor, pressure/flow-sensor, steppermotorshield