The VWTS 6000 vibrating wire temperature sensor is used primarily for the measurement of internal temperature in concrete structures, soil, rock or water.
 
The sensor operates on the principle that when plucked, a tensioned wire vibrates at its resonant frequency. The square of this frequency is proportional to the strain in the wire.
 
Around the wire is a magnetic coil which when pulsed by a vibrating wire readout or data logger interface plucks the wire and measures the resultant resonant frequency of vibration.