A method and a device for measuring a transition rate between a first phase of a material and a second phase of the material wherein the material is solid or liquid in the first phase and gaseous in the second phase. A thermopile which includes a plurality of conductor transitions at an interface area between the first and second phases. The thermopile has a first portion which includes every second one of the conductor transitions, and a second portion that includes the remaining conductor transitions. In addition, the method includes measuring a thermoelectric voltage that is applied on the thermopile and that represents a temperature difference between the first and second portions of the thermopile.