Hypoxia Alert, Oxygen Sensor with Alphasense O2-A2

Hi,

Could anyone help me for my project,

The objectif of this project is to make a hypoxia alert or more precisely an oxygen sensor that create an alarm signal when the percentage of oxygen in the air is less than 19%.

The principal materials that I use are :

  1. Arduino Uno
  2. Alphasense Oxygen Sensors O2-A2
  3. LED
  4. Buzzer

Right now, I don't know how Arduino can extract the signal from the Oxygen Sensors (the interface between the sensor and Arduino).

I also have the problem for the calibration of the sensor (maybe with a button to fix a value when the oxygen percentage at 21%)

Besides, I have some restrictions for this project, I cannot use any transmitter board available on the market, I have to make my own circuit board for the interface between the sensor and Arduino (Signal amplification etc.)

Thank you,

Izzat:
I don't know how Arduino can extract the signal from the Oxygen Sensors (the interface between the sensor and Arduino).

What does the sensor datasheet tell you about the characteristics of signal?

juggerHorn:
What does the sensor datasheet tell you about the characteristics of signal?

Output (μA) @20.9%O2 : 80 to 120

O2A2.pdf (100 KB)

I have used an instrumentation amplifier with a similar O2 sensor before. It was easy to do but did require a negative voltage supply.

Are you going to make circuit boards or do you need a recommendation for a breadboard compatible part?

MorganS:
I have used an instrumentation amplifier with a similar O2 sensor before. It was easy to do but did require a negative voltage supply.

Are you going to make circuit boards or do you need a recommendation for a breadboard compatible part?

I am going to make my own printed circuit boards, and I need recommendation/suggestion for this circuit in order to make the interface between the O2 sensor and Arduino

Here's a schematic and a PCB layout.

I took an old project and just deleted everything except the oxygen sensor and its necessary circuitry. If you don't already have a MAX232 chip in your design to provide a negative voltage then it may work with VNEG connected to AGND but I haven't tested that.


(click on the attachment below to see it at the original size.)

Izzat:
Hi,

Could anyone help me for my project,

The objectif of this project is to make a hypoxia alert or more precisely an oxygen sensor that create an alarm signal when the percentage of oxygen in the air is less than 19%.

The principal materials that I use are :

  1. Arduino Uno
  2. Alphasense Oxygen Sensors O2-A2
  3. LED
  4. Buzzer

Right now, I don’t know how Arduino can extract the signal from the Oxygen Sensors (the interface between the sensor and Arduino).

I also have the problem for the calibration of the sensor (maybe with a button to fix a value when the oxygen percentage at 21%)

Besides, I have some restrictions for this project, I cannot use any transmitter board available on the market, I have to make my own circuit board for the interface between the sensor and Arduino (Signal amplification etc.)

Thank you,

Don’t you also need to know the current altitude or atmospheric pressure?

Paul

I am sure, you need a digital to analog Converter for the o2 sensor.

Take a look at this project, he did something similar with a different 02 sensor. He had to use a analog to digital converter

Link

Or just get the MQ135 air quality sensor. It measures different gas including 02 and cost very less (1-2 Euros)

Yeowch! That Fing diagram is one of the worst and this is what that person puts on display for the rest of the world to see? Not to mention the fact that the parts list shows 7 10K resistors and there's only 3 on the Fing diagram.

There's also a very large amount of "magic happens" in between step 3 and 4. Not a project I would attempt, based on the information presented.

If you're measuring values close to 21% (normal air) then there's a lot of modules available which are much easier to interface than the electrocehemical sensors. CO2meter.com has some great ones. I've used several of their products. If you need to go full-range 0-100% or you have pressure changes to deal with, then you are often forced to use the electrochemical sensors.