Micromechanical heat conductivity sensor used for analyzing gas mixtures containing hydrogen and/or helium has a thermally insulating membrane covered on one or both of its sides by a porous covering plate which permits gas diffusion

摘要

Micromechanical heat conductivity sensor includes a thermally insulating membrane, a heating element formed on the membrane, a temperature-dependent electrical resistor formed on the membrane and a further temperature-dependent electrical resistor. Micromechanical heat conductivity sensor comprises a thermally insulating membrane (1) forming a recess in a poorly heat conducting base plate (2); a heating element formed on the membrane; a temperature-dependent electrical resistor formed on the membrane to measure the temperature of the membrane; and a further temperature-dependent electrical resistor formed on the base plate outside of the membrane to measure the ambient temperature. The membrane is covered on one or both of its sides by a porous covering plate which permits gas diffusion. A cavity (4, 6) is formed between the membrane and the covering plate. An Independent claim is also included for a process for the production of the heat conductivity sensor comprising adhering the porous covering plate to the base plate. Preferred Features: The porous covering plate has a recess forming the cavity. The base plate is made from silicon or a porous ceramic material, especially SiC and Al2O3. The membrane is 0.6-2 mu m thick. The heating element and the electrical resistors are made from Ag, Au, Ni or Pt.