DS18B20 temp sensor IC

Look up my answer on PH probe interfacing.

I've used LMC6001 and it works, it has a reference design in a datasheet. Be aware that PCB board has some leakage too, so that could ruin your measuremetns.

I've desoldered an input lead of DIP package of the frontend opamp and soldered it directly to BNC so it does not touch anything and there is only air and BNC isolation around the input signal.

Otherwise, I was getting wrong results. This is how I measured opamp input current. No matter how vigoriously I cleaned the PCB (the friend whom I was helping with this probe is a chemist, he knows some things about cleaning stuff), too much current was going into opamp input untill I connected the input lead directly to BNC.

All you really need to know is contained here: -

Internally the device may have a sensor that produces 10uA per degree or 10mV per degree or it may be like a thermistor or RTD and vary its resistance to indictate temperature. This is Maxim IP and we are not allowed to know what method they use unless they tell us. If it's not in the data sheet then we cannot know - but you could assume it is one of the four methods I've mentioned and give details in your presentation of all ideas.

If you want to know the types of constant voltage or current sensors that could be used try looking up the AD590 (constant current at 10uA per degC) or the TMP36 (10mV per degC). I'm not aware of a particular name that describes the technology.