How to use KE-25 Oxygen Sensor with arduino

In this tutorial I will tell you how I read an KE-25 oxygen sensor with arduino.

This sensor is self generated voltage, so it doesn’t need any voltage source to operate. But it has so small voltage output. So to make easier to read with an arduino. We should amplify the sensor first.

I use an LM358 op amp IC to amplify the sensor output. I amplify the sensor 11 times. So i use non inverting op amp with 100k and 10k of resistors.

The arduino sketch is easy since this just an analog sensor. We just need to read the ADC value.

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  int sensorValue = analogRead(A0);
  // print out the value you read:
  Serial.print("ADC : ");
  Serial.println(sensorValue);
  float oksigen = sensorValue * 0.28;
  Serial.print(oksigen);
  Serial.println("%");
  delay(300);
}

Since I don’t have an oxygen meter or oxygen analyzer here. I just estimate to get the 21% of oxygen concentration. So I multiply the ADC value with 0.28 in sketch.

You should calibrate the sensor if you want get the right value.

And here’s the full video tutorial on miliohm YouTube channel.