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Emergency hand-replacement ventilator


This ventilator is not intended as a replacement for high-end ventilators. It is, instead, just intended to replace the hand of a medical person using a manual ventilator (Ambu-bag / Bag Valve Mask) with an automated hand.

Important note: Ventilators are a class II medical device. This means that you would need to go through a regulatory approval process before it can be used. It would have to be designed and manufactured to a quality standard and taken through clinical trials before getting approval from the FDA or equivalent regulatory body in your country. This design is NOT approved! It is only intended to give people ideas for other emergency ventilator applications.

Note, also, that because our additive manufacturing lab is currently on lock-down because of COVID-19, we have not been able to physically test this design yet. This is why we are making the design open-source to all so that others can print it, test it and improve it. As soon as we are able to build and test our own we will, no doubt, be improving it, and will then make all the new files available here.

At best, this type of ventilator could only be used as a controlled mechanical ventilation system (CMV). This type ventilation does not allow any synchronization with the patient’s own breathing and is only allowed when patients are deeply unconscious and paralyzed. It could, potentially, also be used to transport patients needing ventilation from one place to another, thus freeing up the hands of medical person that might, otherwise, have to ventilate the patient with an Ambu-bag.

In its current configuration, we use an Arduino Nano as the micro-controller to control the ventilator. We use a simple IR sensor to control the volume/tidal flow of the ventilator (IE: mimic how far the hand closes on the bladder when the medical person closes and opens their hand around the Ambu-bag) (choices of 25%, 50%, 75% and 100% closed). And a simple bit of timing code controls how many breaths per minute (BPM) are required (IE: the frequency at which the medical person closes and opens their hand) (choices of 10 BPM, 13 BPM, 16 PBM, and 20 BPM). And a bit more code allows the user to choose the inspiration / expiration ratio (I:E ratio) by dividing each BPM period into a proportion of time to close the hand and another to open the hand (choice of 1:1, 1:1.3, 1:1.7, 1:2). Selection for all three variables is done via 4 position rotary switches. We chose to use rotary switches to give the user instant access to the various parameters. If desired, however, an LCD and menu system could easily be added access more variables.

If you come up with any further improvements, please email them to us at olaf.diegel@auckland.ac.nz and we'll update the downloadable files on the site.

Bill of Materials

Mechanics: 4 x printed components and 2 x laser cut panels and ABS Enclosure. We recommend printing the parts with a powder bed fusion system (SLS/MJF). STL, X_T parasolid files and DXF files are available HERE

Code: Arduino code and electronic diagram are available HERE. Note that you may need to make a few minor adjustments to the code if you, for example, use a different RPM motor, etc.

1 x ABS Enclosure


1 x Relay control board


1 x 37mm diameter, 6mm shaft, 80 RPM, high torque geared DC motor (such as a GM37 3525 motor)


2 x miniature micro-switches, @ US$3.57


1 x 2.5mm DC socket


1 x ultra mini rocker switch


1 x Arduino Nano


3 x 4 position rotary switches, @ US$3.51


Acrylic for laser cut lid, 240mm x 148mm


1 x Bag Valve Mask (Ambu-bag) bladder. or similar


Miscellaneous common electronics (10Kohm resistors)

Wires for electronics

2 x M6 x 30 shank bolt/screw, 25mm shank & 2 x nylock nut

6 x M4 x 12 machine screws & 2 x 2mm x 12 Self-tapping screws to mount acrylic lids

several 2mm x 12mm self-tapping screws to mount all electronics

3 x M3 x 10 machine screws to attach motor

4 x 10mm diameter x 5mm thick rubber feet


Total excluding 3D printed components



copyright 2020, olaf diegel