ADVANTAGES
Very small 
No need for any reference gas
Response time << 1 second
Lifespan >> 1 year on clean gases
Oxygen partial pressure measured: 10-30 to 10 atm
Resistance to total pressure > 400 atm
Resistance to thermal shock > 100 cycles between 20 and 700°C in 10 seconds

PRINCIPLE OF MEASUREMENT 
At high temperature, zirconia conducts oxygen ions. When the two metal-plated surfaces of a zirconia element come into contact with two gaseous atmospheres with different oxygen content, an electrochemical voltage develops between these two surfaces.
This voltage follows the Nernst equation.

EXAMPLES OF APPLICATIONS
Control of combustion and energy saving
Leak detection on neutral gas circuits, glove-boxes ...
Basic studies (public and private research)
Control of atmosphere (heat treatment, conservation of foodstuffs...)