In 1724, Daniel G. Fahrenheit invented the modern thermometer. For his thermometer, he used a mercury column sealed within glass as he found that mercury had a more constant rate of expansion and a wider temperature range compared to that of the alcohol thermometers in use at the time. The first short clinical thermometer was not invented until 1866. An English physician Sir Thomas Clifford Allbutt was the first to introduce the modern clinical thermometer, a welcome alternative to the foot-long instrument that required 20 minutes to register a patient's temperature.

Apart from liquid and gas thermometers, there is a wide range of hi-tech thermometers available for measuring body temperature. An electronic predictive thermometer uses a temperature sensor, a predictive algorithm, and a display. The sensor is in the probe, which is covered by a disposable probe cover. The sensor connects to the box containing the central processing unit, where it is also stored when not in use. The thermometer displays the predicted temperature based on the rate of increase during the first few seconds. The thermometer then beeps when it digitally displays a prediction.