PRT100’s are very nice , but often when you include amplifier errors , the result can be not as good as you hope .
I would use ds18b20 sensors , but calibrate them against each other and use in hi resolution settings .
I’ve done this will a drilled aluminium block that you can fit the two sensors in . Using a third thermometer ( which obviously doesn’t need to be particularly special , as the error change verses temperature will be small ) you can get the difference between the two DS probs at various temperatures around the region of interest .
These sensors are usually very close to each other , but have a characteristic curve to the temperature response , giving rise to the +- 0.5c quoted figure .
I remember those Serls bars experiments , lots of possibilities to get wet !!