Thermal sensor using the differential thermal analysis for the detection of relative humidity

This article describes a new humidity sensor using the technique of differential thermal analysis (DTA). The energy of water vaporisation is estimated via the measurement of the Seebeck voltage of miniature thermocouples used in differential mode on a Peltier module causing condensation from the ambient air. This sensor uses the sensitivity of alloys V2VI3 containing [Bi, Te, Sb, Se], 400‐440μV.K^–1. Experimental measurements have been performed in a climatic chamber at constant temperature. The time variation of the differential Seebeck voltage with relative humidities H_R varying from 10 to 90 per cent makes it possible to identify with precision the point of water evaporation. For each value of the relative humidity, it is directly a function of the condensate mass. The integration of these curves over time makes it possible to calculate the energy of vaporisation and the condensate mass.