A thick film process for producing hydrogen sensors capable of sensing down to a one percent concentration of hydrogen in carrier gasses such as argon, nitrogen, and air. The sensor is also suitable to detect hydrogen gas while immersed in transformer oil. The sensor includes a palladium resistance network thick film printed on a substrate, a portion of which network is coated with a protective hydrogen barrier. The process utilizes a sequence of printing of the requisite materials on a non-conductive substrate with firing temperatures at each step which are less than or equal to the temperature at the previous step.
The present invention provides for variable-range hydrogen sensors and methods for making same. Such variable-range hydrogen sensors comprise a series of fabricated Pd--Ag (palladium-silver) nanowires--each wire of the series having a different Ag to Pd ratio--with nanobreakjunctions in them and wherein the nanowires have predefined dimensions and orientation. When the nanowires are exposed to H.sub.2, their lattace swells when the H.sub.2 concentration reaches a threshold value (unique to that particular ratio of Pd to Ag). This causes the nanobreakjunctions to close leading to a 6-8 orders of magnitude decrease in the resistance along the length of the wire and providing a sensing mechanism for a range of hydrogen concentrations.
The present invention provides for variable-range hydrogen sensors and methods for making same. Such variable-range hydrogen sensors comprise a series of fabricated Pd--Ag (palladium-silver) nanowires--each wire of the series having a different Ag to Pd ratio--with nanobreakjunctions in them and wherein the nanowires have predefined dimensions and orientation. When the nanowires are exposed to H.sub.2, their lattace swells when the H.sub.2 concentration reaches a threshold value (unique to that particular ratio of Pd to Ag). This causes the nanobreakjunctions to close leading to a 6 8 orders of magnitude decrease in the resistance along the length of the wire and providing a sensing mechanism for a range of hydrogen concentrations.
A robust single-chip hydrogen sensor and a method for fabricating such a sensor. By utilizing an interconnect metallization material that is the same or similar to the material used to sense hydrogen, or that is capable of withstanding an etchant used to pattern a hydrogen sensing portion, device yields are improved over prior techniques.
A protective coating for a surface comprising a layer permeable to hydrogen, said coating being deposited on a catalyst layer; wherein the catalytic activity of the catalyst layer is preserved.
An electrical resistive device, including: an array of titania nanotubes open at an outwardly-directed end formed by anodizing at least a portion of a titanium layer; a plurality of palladium (or other noble metal) clusters having been deposited atop the nanotube array; and the nanotube array mechanically supported by an integral support member. The array of titania nanotubes may include a dopant. An exposure of titania nanotube array to radiant energy emitted within a range of frequencies from visible to ultraviolet, in the presence of oxygen, removes a contaminant, if present. The titanium layer may be deposited atop the integral support; or the unique doped titanium layer can be produced, prior to the anodizing thereof, by depositing titanium along with dopant atop the integral support member by a co-deposition process. Also, supported: method(s) of producing the electrical resistive devices.
