Oxygen measurement

Hi

I have an idea, which includes a microcontroller, three LEDS(green, yellow, red) that indicates the level of oxygen in the area, and ofcourse a Oxygen sensor.

I'm probably going to use a MSP430 microcontroller or a STM32 Nucleo board.
As for the sensor, im not quite sure on it yet, at that is why im posting this thread.

So i am open for ideas for which oxygen sensor I can use, and it would be really helpful if you could explain how the given sensor works.
I have experience in using analog sensor and ADC on the microcontroller.
As for the microcontroller, if you think that there is a better fit out there, you're welcome to share your thoughts.

Best Regards
Poul M. H. Poulsen

Welcome to ETO!
Has Google come up with a short list for oxygen sensors?

How about a hego oxygen sensor for car exhausts, they have a narrow band sensing range.

How about a CO2 and CO sensor as well.