# US 12,000,777 B2 · Volume changeable polymer humidity sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,000,777 B2 - Document ID: US12000777B2 - Status: Granted - Kind: B2 - Application number: 17/181,845 - Filed: 2021-02-22 - Published: 2021-12-23 - Granted: 2024-06-04 - Earliest claimed: 2020-06-17 - Assignees: Postech Research and Business Development Foundation - Applicants: POSTECH Research and Business Development Foundation - Inventors: Jaehyuck Jang; Junsuk Rho - Web page: https://patentgrep.com/patent/US12000777B2 ## CPC - G01N 21/3554: for determining moisture content - G01B 11/06: for measuring thickness {; e.g. of sheet material (thickness measurement by thermal means G01B21/085)} - G01N 21/81: Indicating humidity - G01B 11/0625: {with measurement of absorption or reflection} - G01N 2021/7723: {Swelling part, also for adsorption sensor, i.e. without chemical reaction} - G01N 2021/7789: {Cavity or resonator} - 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) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS ## Abstract Disclosed are a sensor including a first metal layer and a second metal layer facing each other, and a volume changeable layer disposed between the first metal layer and the second metal layer and capable of absorbing a material to change the thickness thereof, wherein at least one of the first metal layer and the second metal layer is a semi-transmissive layer and the sensor indicates a color change by changing a resonance wavelength of light transmitted through the semi-transmissive layer according to a change in thickness of the volume changeable layer, and a sensor device, an electronic device, a smart window, and an IoT system including the same. ## Claims ### Claim 1 A sensor, comprising a first metal layer and a second metal layer, the first metal layer and the second metal layer facing each other, and a volume changeable layer disposed between the first metal layer and the second metal layer, the volume changeable layer being configured to absorb a material to change the thickness thereof, wherein the first metal layer and the second metal layer are a first semi-transmissive metal layer and a second semi-transmissive metal layer, respectively, the first semi-transmissive metal layer and the second semi-transmissive metal layer each having a thickness of about 2 nm to about 50 nm, the first semi-transmissive metal layer is a light incident layer into which external light including a visible wavelength spectrum is incident, the second semi-transmissive metal layer configured to transmit light of a resonance wavelength enhanced by repetitive reflection between the first semi-transmissive metal layer and the second semi-transmissive metal layer, and the sensor indicates a color change by changing a resonance wavelength of light transmitted through the second semi-transmissive metal layer according to a change in thickness of the volume changeable layer. ### Claim 2 (depends on 1) The sensor of claim 1, wherein inner surfaces of the first semi-transmissive metal layer and the second semi-transmissive metal layer facing each other have a mirror surface configured to reflect at least a portion of light of a visible wavelength spectrum. ### Claim 3 (depends on 1) The sensor of claim 1, wherein the volume changeable layer is configured to expand by absorption of the material and contract by discharge or loss of the material. ### Claim 4 (depends on 1) The sensor of claim 1, wherein the material comprises moisture. ### Claim 5 (depends on 1) The sensor of claim 1, wherein the thickness of the volume changeable layer changes in the range of about 50 nm to about 800 nm. ### Claim 6 (depends on 1) The sensor of claim 1, wherein the volume changeable layer comprises an insulating polymer with three-dimensional structure. ### Claim 7 (depends on 6) The sensor of claim 6, wherein the insulating polymer comprises hydrogel. ### Claim 8 (depends on 1) The sensor of claim 1, wherein the volume changeable layer comprises a moisture absorbing polymer, and the sensor is a humidity sensor. ### Claim 9 (depends on 1) The sensor device, comprising the sensor of claim 1, and a photovoltaic cell configured to convert light transmitted through the sensor into an electrical signal. ### Claim 10 (depends on 9) The sensor device of claim 9, wherein the photovoltaic cell comprises a light absorbing layer configured to absorb light of at least a portion of a wavelength spectrum of about 400 nm to about 700 nm. ### Claim 11 (depends on 10) The sensor device of claim 10, wherein the absorption spectrum of the light absorbing layer of the photovoltaic cell at least partially overlaps with a transmission spectrum of light of the resonance wavelength transmitted through the second semi-transmissive metal layer of the sensor, such that the photovoltaic cell is configured to absorb light of the resonance wavelength transmitted through the sensor and convert the absorbed into an electrical signal. ### Claim 12 (depends on 11) The sensor device of claim 11, wherein a wavelength region in which an absorption rate change is greater than or equal to about 50% among the absorption spectrum of the photovoltaic cell at least partially overlaps with the transmission spectrum of the sensor. ### Claim 13 (depends on 9) The sensor device of claim 9, wherein as the thickness of the volume changeable layer increases, the absorption rate of the photovoltaic cell decreases. ### Claim 14 (depends on 9) The sensor device of claim 9, further comprising a measuring unit configured to measure an amount of light absorbed by the photovoltaic cell, and a control unit configured to quantify the amount of light measured by the measuring unit. ### Claim 15 (depends on 14) The sensor device of claim 14, wherein the sensor is a humidity sensor, and the control unit is configured to quantify the amount of light as a relative humidity. ### Claim 16 (depends on 9) The sensor device of claim 9, wherein the sensor device is a self-powered device configured to obtain power from light transmitted through the sensor. ### Claim 17 (depends on 1) The sensor of claim 1, wherein the peak wavelength of the transmission spectrum of light transmitted through the second semi-transmissive metal layer belongs to a visible wavelength spectrum. ### Claim 18 (depends on 17) The sensor of claim 17, wherein as the volume changeable layer expands, the peak wavelength of the transmission spectrum of the light transmitted through the second semi-transmissive metal layer is shifted into a direction of a longer wavelength. ### Claim 19 (depends on 9) An electronic device comprising the sensor device of claim 9. ### Claim 20 (depends on 9) A smart window comprising the sensor device of claim 9. ### Claim 21 (depends on 9) An IoT system comprising the sensor device of claim 9.