5. Response time

For each type of device, reducing response time generally means reducing sensitivity. The difficulty is overcome by amplifying the signal to be measured, but this is not without its limitations, as it also amplifies noise of various origins: in ultra-sensitive measurements, you have to take into account the noise inherent in the measurement, which varies as τ ^-1/2 , τ being the device's time constant. This noise manifests itself as an apparent fluctuation in the measured quantity. It is not advisable to aim for a low response time, as thermal phenomena are generally slow.

As an indication, it's no problem to find devices that respond to a fast signal (unit step) in less than 1 s. The response time of thermocouples and thermistors can be very short, depending on the configuration. Smaller thermistors are rarer, as they...