Medical thermometer and displaying temperature became available, electronic thermometers (often called "digital", because they display numeric values) have been used. Many display readings to great precision (0.1 °C or 0.2 °F, sometimes half that), but this should not be taken as a guarantee of accuracy: specified accuracy must be checked in documentation and maintained by periodical recalibration. A typical inexpensive electronic ear thermometer for home use has a displayed resolution of 0.1 °C, but a stated accuracy within ±0.2 °C (±0.35 °F) when new. The first electronic clinical thermometer, invented in 1954, used a flexible probe that contained a Carboloy thermistor. Types
Six's thermometer in the push-button type with the magnetic plate in place, there is a risk of damaging the weak magnet behind the scale, or magnetising the steel in the markers either weakening or enhancing the pulling force against the capillary tube on all or part of the scale so that the thermometer no longer works properly. The original Six's thermometer design contains mercury, which has been banned for most uses in the European Union and some other parts of the world. In 2006, S.Brannan & Sons Ltd, a UK company, was granted a patent for a mercury-free version of Six's maximum–minimum