# US 12,110,407 B1 · Ceramic-based humidity sensitive material with liquid polymeric delivery vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,110,407 B1 - Document ID: US12110407B1 - Status: Granted - Kind: B1 - Application number: 18/059,088 - Filed: 2022-11-28 - Granted: 2024-10-08 - Earliest claimed: 2022-11-28 - Assignees: United States of America as represented by the Administrator of NASA - Applicants: United States of America as represented by the Administrator of NASA - Inventors: Terry D. Rolin; Cameroun Grace Sherrard; Ian Kent Small - Web page: https://patentgrep.com/patent/US12110407B1 ## CPC - C09D 11/52: Electrically conductive inks - C09C 1/3692: {Combinations of treatments provided for in groups C09C1/3615 - C09C1/3684} - C09C 3/041: {Grinding} - C09C 3/06: Treatment with inorganic compounds {(C09C3/006, C09C3/048 take precedence)} - C09D 11/037: characterised by the pigment - C09D 11/101: Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing - C09D 11/102: containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds - G01N 27/223: {for determining moisture content, e.g. humidity (rain detectors on vehicle windows B60S1/0825)} - C01P 2002/52: containing elements as dopants - C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer - C01P 2004/64: Nanometer sized, i.e. from 1-100 nanometer - C01P 2006/40: Electric properties - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS ## Abstract A humidity sensitive material includes a lanthanum-doped barium titanate (BaTiO3) co-doped with an alkali hydroxide. A polymeric liquid binder is used as a vehicle to deliver the humidity sensitive material to a substrate or electrode via a 3D-printing process. The humidity sensitive material is highly sensitive to changes in humidity and exhibits rapid and large changes in capacitance and impedance for just a relatively small change in humidity. The humidity sensitive material exhibits significantly large changes in impedance and capacitance over the entire 10-90% RH range. As a result of the high sensitivity of the humidity sensitive material, the log-linear response is significantly easier to calibrate in humidity sensing devices that use the humidity sensitive material. ## Claims ### Claim 1 A method of producing a humidity sensitive material, comprising: providing particles of barium oxide, titanium dioxide and lanthanum hydroxide, wherein all of said particles have an average grain diameter in a range of 20-120 nanometers; mixing 60-70 weight percent of said particles of barium oxide, 30-40 weight percent of said particles of titanium dioxide and 0.2-5.0% weight percent of said particles of lanthanum hydroxide to provide a mixture of particles; heating the mixture of particles in a nitrogen atmosphere at a first predetermined temperature for a first predetermined amount of time to form a sintered mixture; cooling the sintered mixture in the nitrogen atmosphere; milling the sintered mixture to produce milled particles having diameters in a range of 50-700 nanometers; mixing 95-99 weight percent of said milled particles and 1.0-5.0 weight percent of an alkali hydroxide to form a composite dielectric material; milling the composite dielectric material to form a composite dielectric powder; heating the composite dielectric powder in a nitrogen atmosphere at a second predetermined temperature for a second predetermined amount of time; cooling the composite dielectric powder in the nitrogen atmosphere; thereafter mixing 70-80 weight percent of said composite dielectric powder and 20-30 weight percent of a liquid polymeric binder to form a homogenous liquid mixture; depositing a layer of the homogeneous liquid mixture onto a substrate; and processing said substrate with said layer thereon to remove liquid portions of said liquid mixture. ### Claim 2 (depends on 1) The method according to claim 1 wherein in said step of heating the mixture of particles, the first predetermined temperature is in a range of 1150-1350° C. and the first predetermined amount of time is in a range of 5-6 hours. ### Claim 3 (depends on 1) The method according to claim 1 wherein the step of milling the composite dielectric material to provide a composite dielectric powder is implemented for 2-3 hours. ### Claim 4 (depends on 1) The method according to claim 1 wherein in the step of heating the composite dielectric powder, the second predetermined temperature is less than or equal to 850° C. and the second predetermined amount of time is in a range of 10-30 minutes. ### Claim 5 (depends on 1) The method according to claim 1 wherein the alkali hydroxide is selected from the group consisting of potassium hydroxide, sodium hydroxide, rubidium hydroxide and lithium hydroxide. ### Claim 6 (depends on 1) The method according to claim 1 wherein said step of processing the substrate with said layer thereon comprises allowing said layer to cure at room temperature. ### Claim 7 (depends on 1) The method according to claim 1 wherein said step of processing the substrate with said layer thereon comprises heating the substrate with said layer at a temperature that is less than or equal to 110° C. ### Claim 8 (depends on 1) The method according to claim 1 wherein said step of processing the substrate with said layer thereon comprises curing said layer with ultraviolet (UV) light. ### Claim 9 (depends on 1) The method according to claim 1 wherein said step of processing the substrate with said layer thereon comprises curing said layer with a laser. ### Claim 10 (depends on 1) The method according to claim 1 wherein said step of processing the substrate with said layer thereon comprises curing said layer with a laser and ultraviolet (UV) light. ### Claim 11 (depends on 1) The method according to claim 1 further comprising mixing a surfactant with the homogenous liquid mixture so as to lower the viscosity of the liquid polymeric binder and increase the dissolution of the composite dielectric powder in the liquid polymeric binder. ### Claim 12 (depends on 11) The method according to claim 11 wherein the surfactant is a phosphate ester. ### Claim 13 (depends on 1) The method according to claim 1 wherein liquid polymeric binder is an epoxy. ### Claim 14 (depends on 1) The method according to claim 1 wherein the liquid polymeric binder is a photoreactive resin. ### Claim 15 A method of producing a humidity sensing material, comprising: providing particles of barium oxide, titanium dioxide and lanthanum hydroxide, wherein all of said particles have an average grain diameter in a range of 20-120 nm; mixing 60-70 weight percent of said particles of barium oxide, 30-40 weight percent of said particles of titanium dioxide and 0.2-5.0% weight percent of said particles of lanthanum hydroxide so as to form a mixture of particles; heating the mixture of particles at a temperature in a range of 1150-1350° C. in a nitrogen atmosphere for a first predetermined amount of time so as to form a sintered mixture; cooling the sintered mixture in the nitrogen atmosphere; milling the sintered mixture to produce milled particles having diameters within a range of 50-700 nm; mixing 95-99 weight percent of said milled particles and 1.0-5.0 weight percent of an alkali hydroxide selected from the group consisting of potassium hydroxide, sodium hydroxide, rubidium hydroxide and lithium hydroxide to form a composite dielectric material; milling the composite dielectric material to produce a composite dielectric powder; heating the composite dielectric powder in a nitrogen atmosphere at a temperature less than or equal to 850° C.; cooling the composite dielectric powder in the nitrogen atmosphere; thereafter mixing 70-80 weight percent of said composite dielectric powder and 20-30 weight percent of a liquid epoxy binder to produce a homogenous liquid mixture; depositing a layer of the homogeneous liquid mixture onto a substrate; and processing the substrate and said layer to remove liquid portions of the homogeneous liquid mixture. ### Claim 16 (depends on 15) The method according to claim 15 further comprising mixing a surfactant with the homogeneous liquid mixture so as to lower the viscosity of the liquid epoxy binder and increase the dissolution of the composite dielectric powder in the liquid epoxy binder. ### Claim 17 A method of manufacturing a humidity sensor, the method comprising: providing particles of barium oxide, titanium dioxide and lanthanum hydroxide, wherein all of said particles have an average grain diameter in a range of 20-120 nanometers; mixing 60-70 weight percent of said particles of barium oxide, 30-40 weight percent of said particles of titanium dioxide and 0.2-5.0% weight percent of said particles of lanthanum hydroxide so as to form a mixture of particles; heating the mixture of particles in a nitrogen atmosphere at a first predetermined temperature for a first predetermined amount of time so as to form a sintered mixture; cooling the sintered mixture in the nitrogen atmosphere; milling the sintered mixture to produce milled particles having diameters within a range of 50-700 nanometers; mixing 95-99 weight percent of said milled particles and 1.0-5.0 weight percent of an alkali hydroxide so as to form a composite dielectric material; milling the composite dielectric material to form a composite dielectric powder; heating the composite dielectric powder in a nitrogen atmosphere at a second predetermined temperature for a second predetermined amount of time; cooling the composite dielectric powder in the nitrogen atmosphere; mixing 70-80 weight percent of said composite dielectric powder and 20-30 weight percent of a liquid polymeric binder to form a homogenous liquid mixture; providing a first electrode; printing a layer of said homogeneous liquid mixture onto said first electrode; processing said first electrode with said layer thereon to remove liquid portions of said homogeneous liquid mixture; and providing a second electrode on said layer after said liquid portions of said liquid mixture have been removed. ### Claim 18 (depends on 17) The method according to claim 17 wherein said layer has a thickness in a range of 30-50 micrometers. ### Claim 19 A method of manufacturing a humidity sensor, the method comprising: providing a substrate having a first electrode and a second electrode, wherein the first electrode and the second electrode are separated by an electrode gap; providing particles of barium oxide, titanium dioxide and particles of lanthanum hydroxide, wherein all of said particles have an average grain diameter in a range of 20-120 nanometers; mixing 60-70 weight percent of said particles of barium oxide, 30-40 weight percent of said particles of titanium dioxide and 0.2-5.0% weight percent of said particles of lanthanum hydroxide so as to form a mixture of particles; heating the mixture of particles in a nitrogen atmosphere at a first predetermined temperature for a first predetermined amount of time so as to produce a sintered mixture; cooling the sintered mixture in the nitrogen atmosphere; milling the sintered mixture to produce milled particles having diameters within a range of 50-700 nanometers; mixing 95-99 weight percent of said milled particles and 1.0-5.0 weight percent of an alkali hydroxide to provide a composite dielectric material; milling the composite dielectric material to form a composite dielectric powder; heating the composite dielectric powder in a nitrogen atmosphere at a second predetermined temperature for a second predetermined amount of time; cooling the composite dielectric powder in the nitrogen atmosphere; mixing 70-80 weight percent of said composite dielectric powder and 20-30 weight percent of a liquid polymeric binder to form a homogenous liquid mixture; printing a layer of said homogeneous liquid mixture onto said substrate so as to fill the electrode gap and cover portions of the said first electrode and said second electrode; and processing said substrate with said layer thereon to remove liquid portions of said homogeneous liquid mixture. ### Claim 20 (depends on 19) The method according to claim 19 wherein said layer has a thickness in a range of 30-80 micrometers.