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OP-Vent

https://op-vent.stanford.edu/ A different take: without an ambu bag. Claims: A mechanical ventilator design developed by Dally can be assembled quickly, using off-the-shelf parts with a total cost of around $400 — making it an accessible and affordable alternative to traditional, dedicated ventilators, which can cost $20,000 or more. Includes just two central components — a solenoid valve and a microcontroller. The design is called the OP-Vent , and in the video below you can see how bare-bones it is in terms of hardware compared to existing alternatives, including some of the other more complex emergency-use ventilator designs developed in response to COVID-19. Has been developed using input from mechanical engineers and doctors, including Dr. Andrew Moore, a chief resident at Stanford University and Dr. Bryant Lin, a medical devices expert and company co-founder. Can be assembled in as little as five minutes, and is small enough to fit in a Pelican case for easy transpor...
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Definitions :relative fraction of inspired oxygen (relative F IO 2 ),

From https://en.wikipedia.org/wiki/Fraction_of_inspired_oxygen Fraction of inspired oxygen Fraction of inspired oxygen ( Fi O 2 ) is the molar or volumetric fraction of oxygen in the inhaled gas. Medical patients experiencing difficulty breathing are provided with oxygen-enriched air, which means a higher-than-atmospheric Fi O 2 . Natural air includes 21% oxygen, which is equivalent to Fi O 2 of 0.21. Oxygen-enriched air has a higher Fi O 2 than 0.21; up to 1.00 which means 100% oxygen. Fi O 2 is typically maintained below 0.5 even with mechanical ventilation, to avoid oxygen toxicity , [1] but there are applications when up to 100% is routinely used. Often used in medicine , the Fi O 2 is used to represent the percentage of oxygen participating in gas-exchange. If the barometric pressure changes, the Fi O 2 may remain constant while the partial pressure of oxygen changes with the change in barometric pressure.
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Heatsink optimization

https://www.youtube.com/watch?v=8MOTMq9g8Nk
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Tubing

Polythene tubing is low outgasing .Teflon tubing produces the least out-gasing.
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Paralleling Motor Drivers

Do  not parallel L298 brushed motor drivers because they are bipolar transistors. Paralleling may be possible however with MOSFETs.
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Anneal your PLA

3D printed PLA plastic needs to be annealed to 110℃ as otherwise the 'glass transition temperature' i.e. 'softening' of PLA plastic is only 60℃. A low softening temperature will interfere with disinfection. Annealing will shorten and thicken PLA objects slightly ,so care needs to be taken to adjust dimensions for close fit.
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Pressure Sensor Selection

I am eliminating  MPS20N0040D as a pressure sensor possibility.It is only specified for dry non-corrosive gases and the sensitivity might be a problem ,it has no on-chip data conditioning and a stable difference amplifier is needed to amplify its analogue output. Its construction  4  resistors in a wheatstone bridge configuration. Trying out Bosch BMP280   temperature and pressure sensor which has SPI and I 2 C. Beware there are knock-off breakout  boards cloning Adafruit's superior breakout boards  that advertise the superior Bosch BME280 temperature,pressure and humidity which actually have the inferior Bosch BMP280. See https://goughlui.com/2018/08/05/note-bosch-sensortec-bmp280-vs-bme280-sensor-confusion/    the BMP280 boards also have to have the Adafruit BMP280test example program in Arduino has to be changed to /***************************************************************************   This is a library for the BMP280 hu...
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