| Full assembly rendering | Internals |
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This section of the repository describes the physical design of the ventilator and the process of manufacturing the components and fully assembled units.
This is an incomplete, as yet untested design that is not intended to be used on patients.
The repository contains live documents. All documentation here is on a "best effort" but no guarantee basis. Information is incomplete. Pictures, renderings, parts lists and fabrication instructions may contradict each other. Components may or may not connect and integrate as intended. Contents may also be out of date. If you decide to buy or build anything, do so at your own risk.
FIRE HAZARD The below design is not fundamentally safe to be used or tested with oxygen or other volatile gases. Parts of the pneumatic design address the need for controlled pressurized oxygen supply. These aspects of the design have only been tested with pressurized air as proof of concept. Listed components are not safe to use with concentrated oxygen. Oxygen is a volatile substance and at high concentration is an extreme fire hazard. Do not do anything stupid.
No endorsements. Materials listed in these pages include links to various suppliers. This does not constitute any endorsement of specific products nor indication that those components are appropriate and reliable for use in medical devices. These links are simply here for our own convenience, since we all use the repository as our common collaboration space.
Acknowledgements: The following pages contain CAD models for various off-the-shelf components, such as valves, fittings and screws. These have been provided by various suppliers on their websites and may be intellectual property of the respective manufacturer. These models come with no guarantees and do NOT fall under the Apache license which generally applies the rest of our project.
We are currently in the process of designing our v0.4 prototype, plans whereof are captured in some of our outstanding Milestones. The master branch of this repository includes bleeding edge changes. Browse at your own peril. For the latest stable and tested (but also obsolete) version of the design see the Releases page.
If you are a pneumatics or mechanical engineer and intend to contribute to our design, please read our wiki, by which we mean all of it.
If you intend to make any physical components yourself, please become familiar with the manufacturing methods guide. And please help maintain it.
The following pages and CAD models are structured according to the sub-assembly hierarchy that should be followed in building the ventilator. In general, each subassembly CAD model resides in its own directory and should be accompanied by a README file, any renderings, drawings or photos of the physical implementation. The readme file is there to explain the design rationale and any non-trivial manufacturing or quality control steps necessary to produce the part.
There are directories for each custom-designed component or custom assembly involving off-the-shelf components arranged in a special way, or some mix thereof. Off-the-shelf CAD models all reside in the third_party directory with some categorization. If a component requires custom manufacturing, you can safely assume that the necessary files will be in its own directory.
This is a on a best effort basis, so some hardware may reside with CAD assemblies of a scope higher or lower from where they are listed in the parts tables. You should always consult both CAD and verbal documentation before attempting to build anything. It is highly advised that you have your parts and measure them to confirm expected dimensions match, as models may be imprecise.
Exported files for 3d printing or whatever other manufacturing processes are not in the repository. Recently exported files for manufacturing can be found on our Google Drive at Manufacturing/Output files v0.4, maintained on a best effort basis.
The current version of the ventilator assembly is meant to demonstrate its packaging in "production" housing. Based on lessons learned from previous iterations, the ventilator uses a detachable internal assembly, to which all pneumatic components can be mounted and connected. This allows for 360 degree accessibility to components during initial assembly. When complete, this internal assembly is bolted into the enclosure, and the enclosure is screwed shut. The top-rear positioning of the removable enclosure lid provides access to components that will need routine maintenance.
We chose a sheet metal construction because:
- cheap and quick: sheet metal is cheap to fabricate. Unlike plastic parts, it doesn't require any expensive molds. This is great for prototyping stages and should also be an accessible manufacture process in many countries.
- strong and durable: stainless steel and other highly durable materials can be used. The frame and enclosure should be rigid and withstand mechanical stresses.
- staged assembly: we wanted the ability to assemble all internals outside the enclosure. The design is built around a strong bracket upon which all pneumatics and electrical equipment is installed. This makes assembly and maintenance easier. This is also useful when prototyping and making design modifications.
- metric - preference has been given to metric hardware. Metric standard hardware is available worldwide, including countries that prefer imperial standard, but generally not vice versa.
- hex drive - screws with hex drive interface have been chosen. Phillips drive screws are prone to cam-out. Torx and other interfaces may be too exotic and supply chains may be limited in some parts of the world. Hex drive is practical and ubiquitous enough.
- button head - preference is given to button head screws. These are smaller and more flush with the surface than pan head or socket head screws and thus less likely to catch on clothing or other materials, and are also the least visually obtrusive.
- predominantly M4 - where possible, we are standardizing to M4 mounting components. This is to minimize the variety of components to keep in inventory.
#TODO: Update BOM to match CAD
If you are a member of the team and intend to build your own prototype, please read the purchasing guidelines first.
| Item | Quantity | Manufacturer | Part # | Price (USD) | Sources* | Notes |
|---|---|---|---|---|---|---|
| A1 | 1 | RespiraWorks | Wiring harnesses | (0.0) | Rw | Wiring harnesses: these get integrated into the below assemblies |
| A2 | 1 | RespiraWorks | Internals | ~1650.00 | Rw | Internals assembly - includes most pneumatics, electrical and computing components |
| A3 | 1 | RespiraWorks | Enclosure | ~750.00 | Rw | Metal enclosure that contains and protects the ventilator internals |
| A4 | 18 | McMaster-Carr | 92095A188 | 0.10 | C | M4 screws, 6mm: main bracket and closure fastening |
| A5 | 1 | RespiraWorks | Peripherals | 72.98 | Rw | Indispensable components that are strictly outside of the assembly itself |
Total price estimate: USD ~2472.00
Ventilator full assembly CAD model: ventilator.iam
TODO: drawings
A number of custom components may have to be pre-fabricated by contract manufacturer:
- Main board / PCB and daughter board (in electronics assembly)
- Sheet metal components: equipment bracket, electronics support frame, display panel support frame and enclosure
- Acrylic components: pneumatics tray, display panel, back panel and filter panel.
- Various gaskets
There are also various 3d printed components throughout the sub-assemblies. They will not be listed here explicitly. Familiarize yourself with the entire hierarchy of assemblies and print what is needed ahead of time.
Recently exported files for manufacturing can be found on our Google Drive at Manufacturing/Output files v0.4, maintained on a best effort basis.
- Prepare all custom wiring components
[A1] - Complete the internals assembly with all its sub-assemblies
[A2] - Insert internals assembly into enclosure
[A3]and fasten it to the sides with 6x M4 screws[A6] - Install cooling fan
[A4](optional) - Attach main power harness to the PCB and install the closure panel
[A5]using the remaining screws[A6] - Attach power cables and/or human input devices listed in peripherals page
Once the assembly is complete, you may proceed to the software section of the repository and learn how to get its brain working.
While this page is not comprehensive yet, some aspects of connecting sensor tubing and electronics may still be better covered in the (somewhat obsolete) "pizza build" guide.
Some aspects of the production packaged design are detailed in the first section of the (somewhat obsolete)assembly video.
There are currently at least 3 prototypes being worked on in various locations around the world:
| Germantown Maryland |  |
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| Sunnyvale California |  |
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| Visakhapatnam India |  |
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To test a prototype you will need some additional components that are not strictly part of the ventilator itself, such as test lungs. There is additional information on the testing page under the quality assurance section of the repository.