Smartphone Camera Calibration for Lateral Flow Test Quantification

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Solution Overview

Problem

Existing consumer devices like smartphones struggle to provide accurate and calibrated readings of lateral flow immunochromatographic tests due to variations in camera quality and light sources, leading to potential falsified results and the need for certification as medical devices, which is complex and impractical.

Innovation Solution

A system using a smartphone with a digital camera and processor to analyze transient digital images, prioritize the region of interest, and calibrate the camera and light source based on predefined reference images, ensuring accurate optical intensity measurements of response lines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If consumer devices like smartphones are used to capture test results, then ease of operation and accessibility are improved, but measurement precision and reliability deteriorate due to variations in camera quality and light sources

Engineering Contradiction:
Improveease of operationVSAvoidmeasurement precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent transforms the variable parameters of consumer devices (camera quality, light source characteristics) from sources of error into calibration opportunities. By capturing images of calibration targets with known optical properties and adjusting measurement parameters accordingly, the system adapts to each device's specific characteristics, thereby maintaining measurement precision across diverse consumer devices.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces calibration targets and reference objects as intermediaries between the consumer device camera and the actual test results. These intermediaries provide known reference points that enable the system to characterize and compensate for device-specific variations, serving as a bridge that translates diverse device outputs into standardized measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If expensive calibrated scanners are used to determine optical intensities, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a virtual copy of the controlled scanner environment by using computational algorithms to simulate the optical measurement conditions. Instead of requiring physical replication of expensive scanner hardware, the system uses software-based image processing and calibration models to reproduce measurement conditions, thereby achieving scanner-level precision with consumer devices.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical and optical complexity of calibrated scanners with computational methods. Rather than relying on precision-engineered hardware to control lighting and measurement conditions, the system uses algorithms to characterize device behavior and correct measurements computationally, substituting mechanical complexity with information processing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If consumer devices are used without calibration, then ease of operation is improved, but reliability and accuracy of diagnostic results deteriorate

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent performs calibration actions in advance before actual diagnostic measurements are taken. By capturing images of calibration targets and establishing device-specific correction parameters beforehand, the system prepares the measurement system to compensate for device variations, ensuring reliability is established prior to use rather than requiring complex real-time corrections.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where calibration measurements are used to adjust and optimize subsequent diagnostic measurements. The system continuously refines its characterization of the consumer device by comparing measured values against known reference values from calibration targets, using this feedback to improve measurement reliability over time.

Inventive Principle:
Principle #23Feedback

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

Enables precise quantitative analysis of lateral flow tests without specialized equipment, allowing use in point-of-care diagnostics and telemedicine, reducing errors and simplifying certification processes.

Implementation Method 1

analyse said image data for measures of light reflected from said chromatography strip

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP4115169B1Calibration of a digital camera for use as a scanner
Publication Date: 2025.12.03 IMMUNDIAGNOSTIK AG
  • EP4115169B1 patent drawingFigure 1A~2
  • EP4115169B1 patent drawingFigure 3
  • EP4115169B1 patent drawingFigure 3

AI summary

An analyte testing system for quantifying the presence of an analyte in a speciment by immunochromatography. The system comprises a camera test card, depicting a test cassette (10) with an immunochromatography and a handheld processor device (16) comprising a digital camera (16a), a source of light (16b) and a processor (16c), which software and hardware (16c) are configured to make a pose estimation of camera and object and the measures of light in the region of interest of the immunochromatography. The system allows an automatic camera calibration and certification as a scanner for use in point-of-care diagnostics.