Accurate colorimetric based test strip reader system

Patent metadata

Field	Value
Publication number	US-11307147-B2
Application number	US-202016796763-A
Country	US
Kind code	B2
Filing date	Feb 20, 2020
Priority date	Jun 28, 2018
Publication date	Apr 19, 2022
Grant date	Apr 19, 2022

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.

First claim

What is claimed is:

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.

2. The method of claim 1 , wherein the illuminating further comprises:
varying a color of illumination for different ones of the test pads.

3. The method of claim 1 , wherein the at least one digital image comprises still or video digital images.

4. 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.

5. 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.

6. The method of claim 5 , wherein the mobile device is a smartphone or tablet.

7. 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.

8. 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.

9. The method of claim 8 , wherein the interference substances are added individually to the series of analyte solutions.

10. The method of claim 8 , wherein a combination of two or more of the interference substances are added to the series of analyte solutions.

11. 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.

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.

13. 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.

14. The device of claim 13 , wherein the mobile device is a smartphone or tablet.

15. 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.

16. 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.

17. 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.

18. The device of claim 17 , wherein the interference substances are added individually to the series of analyte solutions.

Assignees

• IBM

Inventors

• Lu Minhua
• Siu Vince
• Budd Russell
• Colgan Evan
• Knickerbocker John

Classifications

• G06V20/10

  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) · CPC title

• H04N23/56

  provided with illuminating means · CPC title

• G06V10/507

  Summing image-intensity values; Histogram projection analysis · CPC title

• G01N2201/12761

  Precalibration, e.g. for a given series of reagents · CPC title

• G01N21/80 Primary

  Indicating pH value · CPC title