Open-source USB CPAP machine

Breathe free, night and day.

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Obstructive sleep apnea is a medical sleep disturbance where the patient's airway collapses during sleep, preventing breathing. When blood oxygen levels drop the autonomous part of the brain then awakes the patient enough to resume semiconscious breathing. The patient never wakes enough to become aware of it, but sleep is disturbed, and the patient never enters the crucial deep sleep phases

Continuous Positive Airway Pressure is a conceptually simple solution which splints open the airway using pressurized air, but the devices are all very expensive, therefore treatment of sleep apnea is limited to the rich.

I believe that it is possible to build a simple CPAP machine that is controlled by an external device via USB

Team members can decide which part they want to work on:

  1. A blower to produce pressurized air. The pressure is low, only a few centimetres of water, but it needs to be super quiet, because the patient will be sleeping while the blower is running.
  2. A flow monitor. It is necessary to monitor and record flow, to ensure that the patient is being effectively treated by the device.
  3. A pressure control loop.
  4. A tube from the blower to ...
  5. ... a face mask of some sort, to introduce the pressurized air into the airway.
  6. Software for collecting data for examination in analysis software like Sleepyhead or onkor.

  • Arduino Board

    petrusvorster109/22/2018 at 10:21 0 comments

    Hi All

    Chinese copy-cat Arduino boards run from $8 (R160) on Ebay.

    Spoke to some programmer buddies of mine in the US, they reckon that is by far the best option you have. Use the Arduino open software to program the board then your own software to read and write date to the Arduino drivers.

    Cpap blowers check out ALIEXPRESS.

    Ebay DOES ship to SA, just takes a while.

  • Just starting:

    indigoredster04/21/2018 at 19:33 0 comments

    reminder.... "Remind me to take a photograph of it and post it here. "

    I just go approved for medical on my cpap, so now I can compare the DIY I 'm making w/ the one I will get fitted with.  

    I ordered a mask:

    and (erroneously) a fan that barely meets the specs just to evaluate:

    Brushless Radial Blower - UTUO DUAL Ball Bearing High Speed 12V DC Centrifugal Fan with XH-2.5 Plug 120mm by 120mm by 32mm (4.72x4.72x1.26 inch)

    From Wikipedia: The pressure required by most patients with sleep apnea ranges between 6 and 14 cmH2O. A typical CPAP machine can deliver pressures between 4 and 20 cmH2O. More specialised units can deliver pressures up to 25 or 30 cmH2O. CPAP treatment can be highly effective in treatment of obstructive sleep apnea.

    The motor 

    • Max. Air Flow: 42.45CFM
    • Max. Static Pressure: 41.10mm-H2O ( oops I though it was in cm-h20 )

    The real cpap motors look to be similar to RC motors and ESC's. Should be easily 3d printed:


  • Replacement harness.

    Niel Malan09/19/2017 at 09:16 1 comment

    The Resmed Mirage Quattro  full-face mask I use is a wonderful  design. It fits snugly and it's quiet. 

    It does wear, however, and the part that wears out fastest is the harness. The harness is a nice one-piece design cut out of a neoprene and fleece laminate, with velcro-adjustable straps. 

    The hooks of the velcro wears out the loops of the fleece, so that after a time the velcro no longer works. I've successful sewn velcro loop material to the harness, but eventually the neoprene collapsed too. 

    After some experimentation I was able to devise a replacement harness out of haberdashery elastic, mylar sheet and a stapler. It is custom-made for me without any adjustability, so any practical implementation will need a measurement scheme. 

    Remind me to take a photograph of it and post it here. 

  • Project Started

    Niel Malan03/11/2015 at 08:20 0 comments

    At this point the project is a wish more than a project, but if I put it out there perhaps we can get people to join and create hope for lots of people.

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Andrew wrote 08/28/2021 at 18:57 point

hey @dabell me too! if not, lets start it up again! Im currently hacking my old Philips system one. I've had great success with backpacking with LiPo batteries when I take the humidifier off. My next goal is to actually tear it down and minimize the weight. Might be feasible to do my own embedded system too.

  Are you sure? yes | no

dabell wrote 07/23/2021 at 15:43 point

Is there any activity on this project? I'm interested in building something small/simple/low-power to facilitate off-grid travel/hiking while continuing to breath at night. 

  Are you sure? yes | no

indigoredster wrote 06/19/2020 at 05:34 point

My Airsense10 blower motor finally died just past the 2year warranty. I found a replacement brand new in box for $120 on Ebay. It went in and works perfectly, so now I have the old blower to dissect. I will post pictures of this and then I'll 3D model the impellers( there's 2 front and back.) I'll change the design so that the motor is external to the overall airflow. Like I predicted below, when the motor gave up, I had the lovely experience of breathing the hot coil varnish of this lovely flow-thru design. Must have designed been from a jet engine perspective, but not cool breathing the motor dreggs. Of note: don't use the ozone cleaners on this model, it will eat the bearings which is why I think if failed ultimately. -Lee

  Are you sure? yes | no

indigoredster wrote 06/21/2020 at 23:26 point

My Resmed airsense10 cpap blower died finally just after the 2yr warranty. I took it apart to see how it was made. The air blows from the intake,1st impeller, across the motor coils then 2nd impeller then out. if you have this type, DO NOT run one of those ozone cleaner though it, or alcohol on the input filter, like I did. The ball bearings and races on the output side disintegrated.

About 1 year into it, my motor started to whine, so I got some food grade silicone oil and drilled tiny holes so I could oil the bearings.

The whine went away for about a year till now. After the dissection, the oil was all brown and gooey. I fairly sure the ozone started the whine adversely impacting the bearings. 

Found a new in box replacement on ebay. (Very hard to find these, often listed for $100 used.)

Going to model the impellers (identical) sometime and make an RC motor replacement and somehow keep the motor out of the breathing airflow.
recap: if you cpap blower motor is in the airflow: DONOT run one of those ozone cleaner thought it, or alcohol on the input filter, like I did.

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larrygessman wrote 04/21/2020 at 11:01 point

There is a real need for cpap machines all over the world to treat covid 19 patients (especially in third world countries).  I am in touch with 150 engineers trying to build simple ventilators, who now may shift their efforts to building cpap devices because of poor covid patient survival on ventilators.  I have also designed a method to modify the cpap mask and add a hepa filter to the cpap expired air (which if not filtered will aerosolizes the virus and endanger medical support staff). You can go to you tube, type "larrygessman" into the search engine to see my ventilator and cpap filtering designs.  Please email me at if interested in building cpap devices for treatment of covid 19 patients. 

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indigoredster wrote 01/28/2020 at 19:41 point

Just a note on how not to design a thing: Resmed Airsense 10. The motor is an inline 3phase brushelss turbine/impeller that is enclosed in such a way that the air hits the impeller, runs thru the body of the motor and out. So basically as this motor ages, you breath in any coil enamel or motor detritus etc. My motor developed a bearing whine after about 1 year of operation. I lubed it with miniscule amount of a fine silicone "food grade" lubricant( amazon) using a syringe. This worked for about a month, then the whine came back. 

This lube can't be good for you to breath in quantity, but a necessary evil. I'm not going to re-lube it.

I don't know what the designer was thinking, but any benefit of having the motor cooled in the airflow is no benefit to the user. I also disabled the sms( w/ sim card) cell phone module it has inside, that anyone can hack.

Also the water humidifier tank is a 3 piece nightmare that breaks after a few month and leaks water all over your night table. The lower section is made of a shallow stainless pan molded with a plastic reservoir. The water level is several times the height of the metal pan, so it depends on some shoddy sealing that fails too often. End of rant. -Lee

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Thomas Stilwell wrote 08/30/2020 at 18:03 point

Those are limited to about 10 l/min. For CPAP we need more like 100 l/min at maybe 30 cmh2o.

Like this

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indigoredster wrote 06/11/2018 at 20:17 point

I like this: 

Dremel turbine by Landru

Dremel Turbine Video:

The files can easily be modified for a brushless RC motor.

The video look promising in pressure and flow....

20180611 Lee Studley

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indigoredster wrote 05/17/2018 at 21:40 point

This one might be comparable:

I think an RC 3 phase brushless motor, rc ESC motor drive, Arduino Uno or similar( to close the loop and display information), and a 3D printed impeller and body, etc could work well as the next step.

The controller should implement a compatible log of data format to these open source programs for data analysis of the cpap function:



Lee Studley

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Niel Malan wrote 05/17/2018 at 21:50 point

Thank you, you're doing excellent work! I would not have thought of trying leaf blowers. (They're not very common in South Africa.)

I have also not thought of interfacing with analysis software: Sleepyhead would be my primary choice, because I've used it before. 

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indigoredster wrote 05/17/2018 at 23:11 point

Cool! I'll look more into that one then :-)

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indigoredster wrote 05/17/2018 at 21:30 point


I bought a leaf blower that looked small enough and highly hackable:

It was on sale for $39, but seems to now be ~$60. I found it produces very constant pressure w/o feedback into the control loop at 9v-11vdc. I found and will order a new sensor at mouser from Honeywell that is inexpensive and new:

I've used the open loop setup for about 2 weeks now while waiting for my prescribed unit and it is awesome. The only downside has been lack of humidity. I tried an impromptu mason jar with a custom 2 port lid with 1/2" pvc fitting: an in and out port, 1/2 filled with water( fail:not enough moisture). Then I added a wicking tube ( fail:not enough moisture), then I added a wicking "screen curtain" made of medical gauze( fail:not enough moisture), so tonight I'll put a hole in the side of the bucket and run a ultrasonic humidifier so a percentage gets sucked in the input of the blower. Note: I live in AZ where its very dry anyway.

I figured I could experiment with voltages for speeds. I made a cpap hose adapter for the hose to fit 1/2 length of one of the blower tubes as an air reservoir.
I got the mask, hoses, and blower from amazon. I found it works really well and surprisingly constant pressure at ~10volts all night. I need to make a manometer also as a reference: 

Andrew Senske, President did a great blog on how to do this:

I put it all in a home depot bucket with a towel as an impromptu air filter, then in a cardboard box to keep the sound low. Over all it works well. and I've slept much better like I remember doing in years back:

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battletux wrote 05/12/2016 at 20:43 point

Points 4 and 5 could be negated initially, as you could use commercial products to start with. They are not cheap (£100ish) but they are at least a quarter of the price of a CPAP and fifth of the cost of an APAP.

Once the CPAP design is done then you could look to designing a cheaper mask or nasal pillows.

  Are you sure? yes | no

Niel Malan wrote 05/13/2016 at 11:34 point

I agree. Tube and mask are not priorities, but if someone wants to start work on that, it could one day start saving patients money. The masks wear out, and an affordable replacement would help. 

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battletux wrote 05/13/2016 at 18:53 point

the tubes can be bought cheaply on eBay. A mask with a replaceable seal like the resmed quattro fx would be an idea to keep cost of consumables down.

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Niel Malan wrote 05/13/2016 at 21:43 point

Can't buy on eBay in Africa :-(

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Niel Malan wrote 05/13/2016 at 22:10 point

Brilliant idea, Stuart!

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Niel Malan wrote 07/30/2015 at 14:04 point

Here's an article that shows what a CPAP machine looks like on the inside.

Our's doesn't have to look like that.

  Are you sure? yes | no wrote 07/29/2015 at 11:12 point

Can anyone volunteer and give sketches for how a Cpap machine works? I can provide 3D models that are 3D printable or laser cut. CPAP machines are quite expensive and itnwould go a long way to make one inexpensively.

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Niel Malan wrote 07/30/2015 at 10:05 point

I've added a block diagram to the details above. 

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