Sensors Based on the Principle of Metal Expansion
Metals undergo corresponding elongation in response to changes in ambient temperature; sensors can convert this reaction into a signal in various ways.
Bimetallic Strip Sensors
A bimetallic strip consists of two bonded metal layers with different coefficients of thermal expansion. As the temperature changes, Material A expands more than the other metal, causing the strip to bend. The degree of curvature can be converted into an output signal.
Bimetallic Rod and Metal Tube Sensors
As the temperature rises, the length of the metal tube (Material A) increases, whereas the length of the non-expanding steel rod (Metal B) remains unchanged. This shift in relative position allows the linear expansion of the metal tube to be transmitted and subsequently converted into an output signal.
Sensors Based on the Deformation Characteristics of Liquids and Gases
Liquids and gases also undergo corresponding volumetric changes in response to temperature fluctuations.
Various structural designs can convert these expansion-induced changes into positional shifts, thereby generating a positional output (e.g., via potentiometers, inductive displacement sensors, baffle mechanisms, etc.).
