Contact temperature sensors measure their own temperature. We derive the temperature of the object the sensor is in contact with, knowing that the two are in thermal equilibrium. That is, there is no heat flow between them. When should contact temperature probes be used?

1. When you can make good thermal contact with the object or liquid

2. If the expected temperature is less than ~1°C or greater than about –700°C

3. If we can accept a response time greater than other technologies (plunger probes, screw probes, etc.)

Good thermal contact means that the sensor and the object or liquid are the same temperature or very close to each other. This is usually the case if the size and mass of the sensor are small compared to what is being measured. You must maintain this physical contact by soldering, squeezing, gluing, or using some other reliable method of attaching the sensor to the object.