Smartphone Colorimetric Measurement Using Calibrated Test Strip

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Solution Overview

Problem

Current diagnostic technologies for micronutrient deficiencies and infectious diseases are costly, inaccessible, and often require laboratory analysis, which is slow and not widely available, especially in resource-limited settings, limiting timely and accurate diagnosis and treatment.

Innovation Solution

A smartphone-based point-of-collection diagnostic system that uses colorimetric test strips and a smartphone accessory for accurate, consistent, and reliable quantitative measurements of analytes in bodily fluids, such as saliva, sweat, and blood, enabling rapid and portable testing independent of the smartphone platform.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional laboratory diagnostic tests are used, then measurement precision is improved, but device complexity and cost increase, and accessibility decreases

Engineering Contradiction:
Improvediagnostic measurement accuracyVSAvoidlaboratory infrastructure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential diagnostic function from complex laboratory infrastructure by using portable colorimetric test strips that can be performed at the point of collection. The test strips contain all necessary reagents and chemistry in a disposable format, eliminating the need for centralized laboratories while maintaining diagnostic capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses disposable colorimetric test strips as cheap, single-use diagnostic tools. Each test strip is a self-contained, low-cost unit that can be discarded after use, replacing expensive, complex laboratory equipment with affordable, single-use alternatives that maintain measurement precision.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If centralized laboratory analysis is used, then measurement precision is improved, but loss of time increases and productivity decreases

Engineering Contradiction:
Improvediagnostic test accuracyVSAvoiddiagnostic turnaround time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The test strips are pre-loaded with all necessary reagents, buffers, and chemistry components before use. This preliminary preparation allows immediate testing at the point of collection without requiring sample transport, laboratory setup, or sequential processing steps, dramatically reducing diagnostic turnaround time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent eliminates intermediate steps such as sample transport, receipt processing, and laboratory queueing by enabling direct testing at the point of collection. The rapid colorimetric reaction occurs immediately upon sample application, rushing through the diagnostic process in minutes rather than days or weeks.

Inventive Principle:
Principle #21Skipping (Rushing through)

3Ease of operation

If smartphone-based colorimetric measurement is used, then ease of operation and accessibility are improved, but measurement precision may worsen due to variability in smartphone cameras and lighting conditions

Engineering Contradiction:
Improvepoint-of-collection testing simplicityVSAvoidcolorimetric measurement consistency
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a calibrated reference patch as an intermediary element between the test strip and smartphone camera. This reference patch serves as a mediator that provides a known color standard for calibration, allowing the system to compensate for variations in smartphone camera characteristics and lighting conditions while maintaining measurement precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the measurement parameters by using color space transformations (converting from RGB to HSV or HSL color spaces) and calculating ratios between different color regions on the test strip. This parameter transformation approach normalizes measurements across different smartphone platforms and lighting conditions, maintaining precision while preserving ease of operation.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If quantitative colorimetric measurement is implemented, then productivity is improved, but device complexity increases due to need for calibration and image processing

Engineering Contradiction:
Improverapid on-site diagnostic capabilityVSAvoidsmartphone accessory system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the calibration reference and test strip into a single integrated component. The reference patch is incorporated directly onto the test strip, combining calibration functionality with testing in one unified device. This integration simplifies the overall system by eliminating separate calibration steps and reducing the number of components required.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This system provides immediate, accurate, and cost-effective diagnostic capabilities for micronutrient deficiencies and infectious diseases, improving healthcare access and reducing the burden on healthcare systems, especially in resource-limited settings by enabling rapid, on-site testing.

Implementation Method 1

a colorimetric reactive test region that undergoes a colorimetric reaction in the presence of the target analyte

Methodology Applied
Scientific EffectColorimetric reaction:

Implementation Method 2

obtain a color image of the test region containing the analyte and the calibration region using a smartphone including a light source and an image detector

Methodology Applied
Scientific EffectLight illumination: Light

Data Source

PatentEP2946198B1Smartphone-based apparatus and method for obtaining repeatable, quantitative colorimetric measurement
Publication Date: 2019.10.30 CORNELL UNIVERSITY
  • EP2946198B1 patent drawingFigure 1
  • EP2946198B1 patent drawingFigure 2
  • EP2946198B1 patent drawingFigure 3(a)~3(c)

AI summary

A method for obtaining a point-of-collection, selected quantitative indicia of an analyte on a test strip using a smartphone involves imaging a test strip on which a colorimetric reaction of a target sample has occurred due to test strip illumination by the smartphone. The smartphone includes a smartphone app and a smartphone accessory that provides an external environment-independent/internal light-free, imaging environment independent of the smartphone platform being used. The result can then be presented quantitatively or turned into a more consumer-friendly measurement (positive, negative, above average, etc.), displayed to the user, stored for later use, and communicated to a location where practitioners can provide additional review. Additionally, social media integration can allow for device results to be broadcast to specific audiences, to compare healthy living with others, to compete in health based games, create mappings, and other applications.