The XEN-3880 thermal conductivity gauge measures thermal conductivity of the surrounding gas. Operating on the principle that gases differ in their thermal conductivity, it can be used to measure gas concentration in binary mixture or quasi-binary mixture where component gases have different thermal conductivity. It can also be used as a Pirani gauge to measure pressure in vacuum systems.
The sensor chip consists of a silicon rim with a silicon-nitride membrane. In the center is a heater, with a sensor element measuring its temperature. The chip measures the thermal conductance between the ambient and the center of the membrane.