A surface acoustic wave(SAW) sensor consists of a piezoelectric substrate(a material that changes electrical charges due to mechanical stresses), an interdigitated transducer(IDT)resonator, and an antenna. An IDT is a device with interlocking metallic electrodes that is deposited on the surface of the substrate.
The SAW temperature sensing process involves an interrogation unit transmitting an alternating current electrical signal, which is received wirelessly by the sensor’s antenna. The input signal creates alternating polarities on the IDT where a mechanical wave is generated on the surface of the substrate. The surface wave confined to a resonator is reverted to an electrical signal where it’s echoed back to the interrogation unit. The echo frequency, influenced by
environmental conditions of the sensor’s surface material, is processed as a temperature measurement. The wireless passive operations of SAW systems provide many advantages when monitoring medium voltage switchgear temperature.
In photo show SAW temperature sensor(orange sensors) in MV switchgear.
