I have to read the resistence of three different electrochemical gas sensors. The ranges are:

1. 3k - 60k Ohms MiCS 2611 for O3 reading
2. 100k - 1.5M Ohms MiCS 4514 for NO2 reading
3. 0.8k - 20k Ohms MiCS 4514 for CO reading

Some suggestion for an easy to use circuit? I think to interface this sensor board with an atmega8.

• a part number for the sensor would eliminate any false starts – Scott Seidman Jul 9 '13 at 17:57
• Just something to note; the lower the resistance the higher the concentration of gas, the signal produced is very noisy (perhaps as much as +/- 20%) and its not a linear device. – JIm Dearden Jul 9 '13 at 18:48
• Where did you get the sensors? – starblue Jul 10 '13 at 20:12

I'll go for the low hanging fruit here.

I suggest voltage dividers for each of the three sensors. Be sure to use stevenvh's formula for determining your other resistors for each divider: Resistor formula for voltage dividers

In short:

$$R = \sqrt{R_{min} * R_{max}}$$