Accurate colorimetric based test strip reader system

Patent metadata

Field	Value
Publication number	US-10605741-B2
Application number	US-201816022282-A
Country	US
Kind code	B2
Filing date	Jun 28, 2018
Priority date	Jun 28, 2018
Publication date	Mar 31, 2020
Grant date	Mar 31, 2020

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;
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, wherein the method further comprises:
obtaining at least one digital image of calibration pads, wherein the calibration pads have color reference patches that make up a series scale of colors of known chromaticity;
analyzing a color of the color reference patches from the at least one digital image of the calibration pads by i) splitting the at least one digital image of the calibration pads into its component red, green and blue (RGB) channels, and ii) measuring an intensity of each of the RGB channels;
obtaining plots of the intensity of each of the RGB channels against the known chromaticity of the color reference patches; and
storing the plots.

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:
creating the calibration curves by:
obtaining at least one digital image of the calibration pads and of test strips wetted with a series of analyte solutions having known pH at various analyte concentrations;
adjusting the color intensity from the at least one digital image of the test strips using a normalization factor determined from the plots; 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.

8. The method of claim 7 , 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.

9. The method of claim 7 , 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.

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

11. The method of claim 9 , wherein a combination of two or more of the interference substances are added to the series of analyte solutions.

12. 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.

13. A method, comprising:
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 series of analyte solutions all have a same pH, and analyte concentration is varied amongst the series of analyte solutions, and wherein the calibration pads have color reference patches that make up a series scale of black, white, red, green and blue colors of known chromaticity; 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.

14. The method of claim 13 , 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.

15. The method of claim 14 , 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.

16. The method of claim 13 , further 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; 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 affect the color intensity.

17. The method of claim 16 , wherein the illuminating further comprises:
varying a color of illumination for different ones of the test pads.

18. 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;
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, wherein the processor is further configured to perform:
obtaining at least one digital image of calibration pads, wherein the calibration pads have color reference patches that make up a series scale of colors of known chromaticity;
analyzing a color of the color reference patches from the at least one digital image of the calibration pads by i) splitting the at least one digital image of the calibration pads into its component red, green and blue (RGB) channels, and ii) measuring an intensity of each of the RGB channels;
obtaining plots of the intensity of each of the RGB channels against the known chromaticity of the color reference patches; and
storing the plots.

19. The device of claim 18 , wherein the at least one digital image is obtained using a digital camera that is a component of a mobile device.

20. The device of claim 19 , wherein the mobile device is a smartphone or tablet.

21. The device of claim 18 , 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.

Assignees

• IBM

Inventors

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

Classifications

• G01N2021/7759

  Dipstick; Test strip · CPC title

• G01N2021/8488

  the band presenting reference patches · CPC title

• G06T7/90

  Determination of colour characteristics · CPC title

• G01N21/80 Primary

  Indicating pH value · CPC title

• G01N2201/12746

  Calibration values determination · CPC title