# US 2008/0219499 A1 · Method for reading test strips

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- Number: US 2008/0219499 A1
- Document ID: US20080219499A1
- Status: Published application
- Kind: A1
- Application number: 12/074,823
- Filed: 2008-03-06
- Published: 2008-09-11
- Earliest claimed: 2007-03-09
- Assignees: Rohm and Haas Company
- Inventors: Walter Jay Gregory; William Harrison Stapelkamp
- Web page: https://patentgrep.com/patent/US20080219499A1

## CPC

- G01N 21/8483: {Investigating reagent band (test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04)}
- G01N 21/27: using photo-electric detection (G01N21/31 takes precedence){; circuits for computing concentration (logarithmic circuits G06G7/24; photometric circuits in general G01J)}
- G06T 7/90: Determination of colour characteristics
- G01N 2021/177: {Detector of the video camera type}
- G01N 2021/5923: {Determining zones of density; quantitating spots}
- G01N 2021/593: {Correcting from the background density}
- G01N 2021/8488: {the band presenting reference patches}
- G01N 2035/00108: {Test strips, e.g. paper}
- G06T 2207/10024: Color image
- 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

## Abstract

There is provided a method for identifying the color intensities of red lines on a white test strip, comprising the steps of (A) attaching said white test strip to a card that is larger and darker than said white test strip, (B) scanning said card with said attached white test strip, (C) creating a digital image of said card, wherein each pixel in said digital image has a Red value, a Green value, and a Blue value, (D) using said digital image to calculate a color intensity for each red line on said white test strip.

## Claims

### Claim 1

A method for identifying the color intensities of red lines on a white test strip, comprising the steps of
(A) attaching said white test strip to a card that is larger and darker than said white test strip,
(B) scanning said card with said attached white test strip,
(C) creating a digital image of said card, wherein each pixel in said digital image has a Red value, a Green value, and a Blue value,
(D) using said digital image to calculate a color intensity for each red line on said white test strip.

### Claim 2 (depends on 1)

The method of claim 1, wherein said step (D) is performed using a method comprising
(a) identifying a first red line, and identifying a first rectangle corresponding to said first red line, wherein said first rectangle
(i) is approximately or exactly centered on said test strip in the horizontal direction,
(ii) is smaller than said test strip in the horizontal direction,
(iii) extends above and below said first red line in the vertical direction,
(b) identifying a second red line, and identifying a second rectangle corresponding to said second red line, wherein said second rectangle
(i) is approximately or exactly centered on said test strip in the horizontal direction,
(ii) is smaller than said test strip in the horizontal direction,
(iii) extends above and below said first red line in the vertical direction,
(c) optionally, repeating said step (b) for each additional red line to identify an additional rectangle corresponding to said additional red line,
(d) performing a color inversion calculation, and
(d) after performing said steps (a), (b), and (c), and (d), calculating the sum of the Green values of all the pixels within each rectangle, to produce a first sum of Green values corresponding to said first rectangle, a second sum of Green values corresponding to said second rectangle, and, optionally, an additional sum of Green values corresponding to each additional rectangle.

### Claim 3 (depends on 2)

The method of claim 2, further comprising the step of calculating the ratio of said second sum of Green values to said first sum of Green values.

### Claim 4 (depends on 1)

The method of claim 1, wherein said test strip is produced by a chromatographic process in which one end of a pre-test strip is placed into a solution, wherein said solution comprises an analyte and a complexing agent capable of forming a complex with said analyte, and wherein said pre-test strip comprises a line of a reference assay material capable of turning red on contact with free molecules of said complexing agent and a line of test assay material capable of turning red on contact with molecules of said complex of said analyte and said complexing agent.

### Claim 5 (depends on 4)

The method of claim 4, wherein said analyte is a polymer.

### Claim 6 (depends on 5)

The method of claim 5 wherein said polymer is a dispersant polymer.

### Claim 7 (depends on 6)

The method of claim 6 wherein said dispersant polymer with one or more detectable terminus selected from chain transfer agents, initiators or fragments thereof, and groups attached to a chain transfer agent.

### Claim 8 (depends on 4)

The method of claim 4, wherein said pre-test strip contains one or more printed image, wherein each printed image is a known distance from each of said line of reference assay material and from said line of test assay material.