Sensors Metal expansion design principles
Metal after the ambient temperature changes will produce a corresponding extension so that the sensor can be reacted in different ways to this signal conversion.
Bimetal sensor
The bimetal is composed of two different coefficients of expansion of metal sheets stick together and the composition, as the temperature changes, than the other metal material A higher degree of expansion, causing bending sheet metal. Bending curvature can be converted into an output signal.
Double metal rod and metal tube sensor
As the temperature increases, the metal tube (material A) length increase, rather than expanded steel rod (metal B) does not increase the length, so that due to the change in position, the linear expansion of the metal tube can be passed. In turn, this expansion can be converted into a linear output signal.
Deformation of liquid and gas sensor design curve
Changes in temperature, liquids and gases will also produce a corresponding change in volume.
Various types of structures can convert this expansion is changed to change the location, so changes in the output generated position (potentiometer, inductive bias, baffle plates, etc.).
Sensing resistor

Metal as the temperature changes, the resistance value is also changed.
Different metals, the change in temperature once, the resistance value change are different, and the resistance value and can be used directly as an output signal.
There are two types of resistance change
Positive temperature coefficient
Temperature = increased resistance
Temperature reduction = resistance decreases
Negative temperature coefficient
Temperature = resistance decreases
Temperature reduction = Resistance increase