The XEN-3920 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 2 silicon-nitride membranes. In the center of each membrane 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.
Standard the XEN-3920 consists of a TO-5 header with the chip, a roof (silicon cover) over the chip to reduce sensitivity to flow effects, and a cap with filter welded onto the TO-5 housing. Next to the chip is a Pt100 or Pt1000 for ambient temperature measurement.