The greatest problem with these sensors is electrolysis and subsequent oxidation, due to the DC current flowing through the sensor in a humid environment.
There are some solutions: Most of the circuits that supposedly feed the sensor with A are bogus as it is apulsed DC at best..
One could try a capacitive sensor...... in theory very good but in practice plagued by issues.
What I have done is to remove constant current from the sensor by feeding it from a transistor that I can switch on and off. I take a measurement every 2-6 hrs and switch the current off in between. Makes a huge difference