Comment by speak_plainly

I think maybe one thing you have to consider is that sensors still require maintenance. Software can measure the length of time the sensor requires to reach equilibrium and send a maintenance required alert and someone cleans it (like if the software expects equilibrium in 10 seconds but the reading settles at 60 seconds, it can calculate the sensor is 80% clogged and requires cleaning). There's also all sorts of techniques that can be used to mitigate gunk depending on how the sensor is being used such as physical wipers, air-blast systems, ultrasonic cleaning systems, and chemical coatings. So as long as some oxygen can get in and an equilibrium is made between the fluid outside the sensor and inside the sensor, you'll get a reading that you can trust.