Halogen detection with solid state sensor
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorEdward S. Kolesar, Jr.
Life of this patent
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Abstract
A solid state thin film detection and measurement apparatus for halogen gas components such as chlorine in a gas mixture is described. The detection cell employs plural response modes to the halogen gas including response to the thermal effect of a halogen and thin film reaction and response to the thermal and ion diffusion effects of the halogen reaction with a halide supporting substrate member. These plural responses are manifested by an electrical resistance change in the thin film element and this change is sensed with a four-lead measurement arrangement. The use of plural measurement cells each of a different composition and computerized multiplexing of thin film resistance signals is included as are identification of possible thin film and substrate compositions.
Claims18
Apparatus for detecting the presence of gaseous first halogen components in an unknown mixture of gases comprising the combination of:
- a detection substrate member comprised of a second halogen chemical compound of a first metal;
- a thin film electrical resistance detector element received on said substrate member and comprised of a second metal in thin film metallic form;
- means for moving a stream of said unknown gas mixture over said detection substrate and detector elements;
- and
- means responsive to the combined detector element unknown gas exposure and the substrate member unknown gas exposure resistance changes in said detector element for indicating the presence of said first halogen components in said unknown mixture of gases.
The method of sensing first halogen element components in a gaseous mixture comprising the steps of:
- conducting a stream of said gaseous mixture over an exposed surface of a thin film first metal detector element;
- conveying a stream of said gaseous mixture over an exposed surface of the detector element supporting substrate member, said substrate member being comprised of a second metal chemically compounded with a second halogen element and being intimately mated physically with said thin film element;
- measuring the electrical resistance change produced in said detector element by the combined reaction of said first halogen element components with said detector element metal and with said substrate member compound;
- and
- correlating said electrical resistance change with a predetermined resistance to halogen element concentration relationship.
A method for measuring first halogen element concentrations in a gaseous effluent mixture comprising the steps of:
- reacting said gaseous mixture with a thermally responding metallic thin film electrical resistance element;
- sorbing first halogen components of said gaseous mixture with a thermally responding solid state metal plus second halogen element thermal compound sensor element;
- communicating heat energy from said sensor element sorbing steps to said thin film electrical resistance element;
- and
- correlating said resistance change with a predetermined resistance change to first halogen element concentration relationship.
Dependencies are inferred from the claim text.