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Poor man’s sensor system for OxyGEN

The emergency ventilators like OxyGEN are devices that in extreme cases are used to give vital support to seriously ill patients . They must be reliable devices and that’s why OxyGEN is completely mechanical thus allowing visual diagnosis of the machine and maintenance can be done by personnel without special qualifications.

Nevertheless, all devices can fail. The power supply might fail or the Ambu could break or the motor may fail and stop rotating. The camshaft could also get locked. OxyGEN is designed to try to minimize these problems, but the 0 fault system does not exist.

In order to use OxyGEN in an hypothetical emergency situation with actual patients, it is essential for the system to be equipped with alarms that will go off when things go wrong. Breathing is an essential process for life, and can’t stop. If it stops, someone should find out as soon as possible in order to solve the problem before it is too late.

The philosophy that OxyGEN has been designed with is that it must be easy to build and that the parts must be easily available. The other pillar of OxyGEN is modularity, the system can have as many addons and modifications as needed, but always in the form of a module without the failure of one affected the entire system.

And that’s why we have designed an alarm system that can be added to OxyGEN after it has been built, without having to modify OxyGEN itself. Furthermore, we have exclusively used massively available components and an Arduino electronic board which can be replaced with an ESP32 (a small microcontroller with integrated Wi-Fi).

The system is based on a single sensor: A small piezoelectric sensor that is inserted under the Ambú, and that detects the pressure changes produced by the compression / decompression of the Ambú. In this way, the system can detect the pressure curve that is generated on the Ambú, show graphs of the pressure cycle if a screen is available and fire alarms when the system is not working.

We have developed a small Arduino program, available here: The program also works with ESP32 chips for use with boards like the NodeMCUs or similar.

The program detects pressure changes to generate a statistics and detect when the ambú is not continuously compressing/decompressing and fires an audible alarm. Additionally since it is compatible with ESP32, this information can be send via Wi-FI in order to aggregate alarms and create plots in a control center, such a central computer.

And all of this, just with a small device called piezoelectric sensor, very common and cheap connected to a microcontroller.

As a great inventor once said: I didn't fail the test, I just found 100 ways to do it wrong.

1 Comment

Fco. Armando Payan Guerrero
Fco. Armando Payan Guerrero
Apr 17, 2020

He revisado su información Matlab y me gustaría tener más información de los parámetros utilizados para las gráficas de inhalación y exhalacion, esto con el fin de entender cómo puedo llevar esas matemáticas a un ambiente de Programación Arduino.

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