Thermometers and hygrometers are measuring instruments for determining the process values of temperature and humidity. Temperature sensors allow the determination of the temperature of solids, liquids and gases. For especially sensitive electronic modules, a combined temperature and hygro sensor can be attached to the circuit board and can manipulate the control system directly through its digital output signal. Pure hygro sensors are used, on the one hand, as electronic components in control units of household appliances or air conditioners and in medical technology. On the other hand, complete measurement devices are useful as mobile moisture sensors for forestry – for measuring moisture in wood – and construction trades, in which they are used to measure moisture in walls.