Calorimetric device for non-destructive measurement of the thermal diffusivity dependency by phase delay

We developed a calorimetric device for measuring thermal diffusivity non-destructively. The calorimetric device was based on the principle that temperature phase delay between a heater and a resistance temperature detector (RTD) is affected by thermal diffusivity of the region between them. The device consisted of an Au wire, as oscillating heat source and a piezoresistor as an RTD. We exerted the experiment, in which air pressure was changed, and observed that the device measured thermal diffusivity of the air.