Board Comparison

 

Size

Power (mA)

Indep. heater power

Enable control

Digital output

Pre-heat (seconds)

Burn-in time (hours)

Board Cost (USD)

Adafruit MiCS-5524

13x20 mm

32

No

Yes

No

~60

24

14.95

MQ-3 Module

20x32 mm

129

No

No

Yes

~170

24

6.99

The pre-heat time was measured from graphs from sensor power on to when the first reading was within +/- 5% of the steady state value. The MiCS-5524 undershoots initially and then quickly recovers ahead of the MQ-3.

The lower power of the Adafruit MiCS-5524 makes it easier to use and less taxing on power supply/batteries. The enable feature could also be useful for power saving if continuous measurement is not required.

The MiCS-5524 is roughly twice as sensitive in terms of Ro/Rs compared to the MQ-3 for alcohol and gasoline (petrol) but care needs to be taken with very high ppm samples as output will fluctuate.

The SGX MiCS FAQ and SGX General FAQs have entries on airflow:

Does airflow have an influence on the measurement?

Yes. Direct airflow on the sensor surface will change the conductivity of the sensor by altering the heated layer temperature. That is why SGX Sensortech recommends placing the sensor behind a Teflon membrane in most applications. The Teflon membrane allows diffusion of the gases, while reducing the influence of the air speed.

Does the gas need to be flowing across the Metal Oxide Semiconductor sensor?

Stable sensor performance relies in part to diffusion control. A minimum gas flow is required to replace gas reacted by the sensor.

This guide was first published on Oct 28, 2018. It was last updated on Oct 28, 2018. This page (Board Comparison) was last updated on May 09, 2019.