# US 11,307,147 B2 · Accurate colorimetric based test strip reader system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,307,147 B2 - Document ID: US11307147B2 - Status: Granted - Kind: B2 - Application number: 16/796,763 - Filed: 2020-02-20 - Published: 2020-06-18 - Granted: 2022-04-19 - Earliest claimed: 2018-06-28 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Minhua Lu; Vince Siu; Russell Budd; Evan Colgan; John Knickerbocker - Web page: https://patentgrep.com/patent/US11307147B2 ## CPC - G01N 21/80: Indicating pH value - G06T 7/90: Determination of colour characteristics - G06V 10/507: {Summing image-intensity values; Histogram projection analysis} - G06V 20/10: Terrestrial scenes (scenes under surveillance with static cameras G06V20/52; scenes perceived from the exterior of a vehicle G06V20/56; scenes perceived from the interior of a vehicle G06V20/59) - H04N 23/56: provided with illuminating means - G01N 2021/7759: {Dipstick; Test strip} - G01N 2021/8488: {the band presenting reference patches} - G01N 2201/0221: Portable; cableless; compact; hand-held - G01N 2201/0627: Use of several LED's for spectral resolution - G01N 2201/127: Calibration; base line adjustment; drift compensation - G01N 2201/12746: Calibration values determination - G06T 2207/10152: Varying illumination - 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) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Techniques for colorimetric based test strip analysis and reader system are provided. In one aspect, a method of test strip analysis includes: illuminating a test strip wetted with a sample with select spectrums of light, wherein the test strip includes test pads that are configured to change color in the presence of an analyte in the sample; obtaining at least one digital image of the test strip; and analyzing color intensity from the at least one digital image against calibration curves to determine an analyte concentration in the sample with correction for one or more interference substances in the sample that affect the color intensity. A calibration method and a reader device are also provided. ## Claims ### Claim 1 A method, comprising: illuminating a test strip wetted with a sample with select spectrums of light, wherein the test strip comprises test pads that are configured to change color in the presence of an analyte in the sample; obtaining at least one digital image of the test strip; creating calibration curves by obtaining at least one digital image of calibration pads and of test strips wetted with a series of analyte solutions having known pH at various analyte concentrations, wherein the calibration pads have color reference patches that make up a series scale of colors of known chromaticity, adjusting the color intensity from the at least one digital image of the test strips using a normalization factor, and plotting the color intensity from the at least one digital image of the test strips against the various analyte concentrations to form the calibration curves; and analyzing color intensity from the at least one digital image against the calibration curves to determine an analyte concentration in the sample with correction for one or more interference substances in the sample that change the color intensity and that, unless corrected for, affect measurement of the analyte concentration, wherein the method further comprises: learning color intensity values for the analyte in the presence of the one or more interference substances using analyte solutions with known analyte concentrations to which the one or more interference substances have been added in order to correct for the one or more interference substances in the sample. ### Claim 2 (depends on 1) The method of claim 1, wherein the illuminating further comprises: varying a color of illumination for different ones of the test pads. ### Claim 3 (depends on 1) The method of claim 1, wherein the at least one digital image comprises still or video digital images. ### Claim 4 (depends on 1) The method of claim 1, wherein the at least one digital image is timestamped, the method further comprising: timing when the test strip is wetted with the sample. ### Claim 5 (depends on 1) The method of claim 1, wherein the at least one digital image is obtained using a digital camera that is a component of a mobile device. ### Claim 6 (depends on 5) The method of claim 5, wherein the mobile device is a smartphone or tablet. ### Claim 7 (depends on 1) The method of claim 1, further comprising: repeating the creating of the calibration curves x times with additional series of analyte solutions having a different known pH at the various analyte concentrations to obtain the calibration curves for a range of pH values. ### Claim 8 (depends on 1) The method of claim 1, further comprising: repeating the creating of the calibration curves y times with the series of analyte solutions having interference substances added to obtain the calibration curves for the interference substances. ### Claim 9 (depends on 8) The method of claim 8, wherein the interference substances are added individually to the series of analyte solutions. ### Claim 10 (depends on 8) The method of claim 8, wherein a combination of two or more of the interference substances are added to the series of analyte solutions. ### Claim 11 (depends on 1) The method of claim 1, wherein the illuminating comprises: providing different color illumination using multiple light-emitting diodes (LEDs) which emit light at different colors. ### Claim 12 A device, comprising: a processor, connected to a memory, the processor being configured to perform: illuminating a test strip wetted with a sample with select spectrums of light, wherein the test strip comprises test pads that are configured to change color in the presence of an analyte in the sample; obtaining at least one digital image of the test strip; creating calibration curves by obtaining at least one digital image of calibration pads and of test strips wetted with a series of analyte solutions having known pH at various analyte concentrations, wherein the calibration pads have color reference patches that make up a series scale of colors of known chromaticity, adjusting the color intensity from the at least one digital image of the test strips using a normalization factor, and plotting the color intensity from the at least one digital image of the test strips against the various analyte concentrations to form the calibration curves; and analyzing color intensity from the at least one digital image against the calibration curves to determine an analyte concentration in the sample with correction for one or more interference substances in the sample that change the color intensity and that, unless corrected for, affect measurement of the analyte concentration, wherein the processor is further configured to perform: learning color intensity values for the analyte in the presence of the one or more interference substances using analyte solutions with known analyte concentrations to which the one or more interference substances have been added in order to correct for the one or more interference substances in the sample. ### Claim 13 (depends on 12) The device of claim 12, wherein the at least one digital image is obtained using a digital camera that is a component of a mobile device. ### Claim 14 (depends on 13) The device of claim 13, wherein the mobile device is a smartphone or tablet. ### Claim 15 (depends on 12) The device of claim 12, wherein the processor when performing the illuminating is further configured to perform: providing different color illumination using multiple LEDs which emit light at different colors. ### Claim 16 (depends on 12) The device of claim 12, wherein the processor is further configured to perform: repeating the creating of the calibration curves x times with additional series of analyte solutions having a different known pH at the various analyte concentrations to obtain the calibration curves for a range of pH values. ### Claim 17 (depends on 12) The device of claim 12, wherein the processor is further configured to perform: repeating the creating of the calibration curves y times with the series of analyte solutions having interference substances added to obtain the calibration curves for the interference substances. ### Claim 18 (depends on 17) The device of claim 17, wherein the interference substances are added individually to the series of analyte solutions.