Micro-machined thin film sensor arrays for the detection of H2, NH3, and sulfur containing gases, and method of making and using the same
First Claim
1. A hydrogen sensor, comprising:
- at least one hydrogen-interactive thin film sensor element comprising a rare earth metal or a rare metal dihydride;
at least one micro-hotplate structure coupled to said hydrogen-interactive sensor element for selective heating of the sensor element; and
a hydrogen-permeable material overlaying each hydrogen-interactive element for selective permeation of hydrogen, wherein said hydrogen-permeable material comprises an alloy to suppress a phase change in said rare earth metal or rare metal dihydride.
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Abstract
The present invention provides a hydrogen sensor including a thin film sensor element formed by metal organic chemical vapor deposition (MOCVD) or physical vapor deposition (PVD), on a micro-hotplate structure. The thin film sensor element includes a film of a hydrogen-interactive metal film that reversibly interacts with hydrogen to provide a correspondingly altered response characteristic, such as optical transmissivity, electrical conductance, electrical resistance, electrical capacitance, magneto resistance, photoconductivity, etc., relative to the response characteristic of the film in the absence of hydrogen. The hydrogen-interactive metal film may be overcoated with a thin film hydrogen-permeable barrier layer to protect the hydrogen-interactive film from deleterious interaction with non-hydrogen species. The hydrogen permeable barrier may comprise species to scavenge oxygen and other like species. The hydrogen sensor of the invention may be usefully employed for the detection of hydrogen in an environment susceptible to the incursion or generation of hydrogen and may be conveniently configured as a hand-held apparatus.
24 Citations
47 Claims
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1. A hydrogen sensor, comprising:
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at least one hydrogen-interactive thin film sensor element comprising a rare earth metal or a rare metal dihydride;
at least one micro-hotplate structure coupled to said hydrogen-interactive sensor element for selective heating of the sensor element; and
a hydrogen-permeable material overlaying each hydrogen-interactive element for selective permeation of hydrogen, wherein said hydrogen-permeable material comprises an alloy to suppress a phase change in said rare earth metal or rare metal dihydride. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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26. A hydrogen sensor device, comprising:
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A hydrogen-interactive thin film sensor element comprising a rare earth metal and /or a rare earth metal dihydride;
a micro-hotplate structure Coupled to said hydrogen-interactive sensor element for selective heating of the sensor element;
a hydrogen-permeable material overlaying said hydrogen-interactive sensor element for selective permeation of hydrogen, wherein said hydrogen-permeable material comprises an alloy to suppress a phase change in said rare earth metal or rare metal dihydride; and
a detector coupled with said hydrogen-interactive sensor element for sensing a detectable change of physical property of the sensor element on exposure to hydrogen and generating a correlative output indicative of hydrogen presence.
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36. A method of fabricating a hydrogen sensor on a substrate, comprising:
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constructing on the substrate a micro-hotplate structure; and
forming on the micro-hotplate structure a hydrogen-interactive thin film comprising a rare earth metal and/or a rare earth metal dihydride that upon exposure to hydrogen exhibits a detectable change of at least one physical property, and wherein the hydrogen-interactive thin film is arranged to be heated by the micro-hotplate structure; and
forming on the hydrogen-interactive thin film a protective over layer comprising a hydrogen-permeable material for selective permeation of hydrogen, wherein said hydrogen-permeable material comprises an alloy to suppress a phase change in said rare earth metal or rare metal dihydride.
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Specification