Test Strip Alignment Detection Using Multi-Wavelength Reflectance

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Solution Overview

Problem

Existing test systems for analyzing body fluids, such as blood sugar, face issues with incorrect test strip alignment leading to unreliable measurements and potential repeat tests, which can have fatal consequences, especially in blood sugar monitoring.

Innovation Solution

The system uses at least two light sources with different spectral intensity distributions to record reflectance measurements at various wavelengths, allowing the control unit to determine correct or incorrect alignment by comparing these values with predetermined reference values, eliminating the need for additional markings or detectors and ensuring reliable differentiation between the test field and carrier film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If separate control light sources or additional detectors are used for position detection, then alignment detection capability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvealignment detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measuring unit's existing light sources and detector are made multi-functional by enabling them to perform both analytical measurements and alignment detection. The control unit processes reflectance measurement values at different wavelengths to determine alignment status, allowing the same hardware components to serve dual purposes without adding separate control light sources or detectors.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention utilizes changes in reflectance measurement values at different wavelengths as indicators of alignment status. By analyzing spectral parameters (reflectance at multiple wavelengths) from the existing measuring unit, the system can detect alignment errors without requiring additional hardware, transforming parameter analysis into a diagnostic tool for positioning.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If additional markings are placed on the test strip for positioning, then alignment accuracy is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmanufacturing effort
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The test strip structure itself provides alignment information through its inherent optical properties. Different regions of the test strip (test field, network, carrier film) have naturally different reflectance characteristics at various wavelengths, eliminating the need for artificial markings. The system uses the test strip's own structural features for self-positioning detection.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention detects alignment by measuring changes in reflectance parameters at different wavelengths from the test strip's existing structure. The spectral signature of each test strip region serves as a unique identifier, allowing the control unit to determine correct positioning without any additional markings or labels on the consumable.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If multiple light sources with different wavelengths are used, then alignment detection reliability is improved, but use of energy increases

Engineering Contradiction:
Improvealignment detection reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The multiple light sources with different wavelengths are already part of the measuring unit's design for analytical measurements. By repurposing these existing multi-wavelength sources for alignment detection, the system achieves reliable positioning without adding extra energy-consuming components. The same energy input serves dual functions: analysis and alignment verification.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention extracts alignment information from spectral parameter variations at multiple wavelengths using the existing light sources. By analyzing the pattern of reflectance changes across the wavelength spectrum, the system achieves reliable alignment detection while utilizing the energy already invested in the multi-wavelength measurement process.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If alignment checking is performed, then measurement reliability is improved, but measurement time increases

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidmeasurement time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The alignment detection is performed as a preliminary step before the actual analytical measurement. The control unit evaluates reflectance measurement values at different wavelengths to determine alignment status, and only proceeds with the full measurement sequence if alignment is correct. This preliminary check prevents wasted time on misaligned test strips while maintaining measurement reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The measuring unit performs both alignment detection and analytical measurement using the same hardware and processing pipeline. The reflectance measurement values are first evaluated for alignment purposes, and if correct, the same data stream is used for the full analytical determination, minimizing additional time requirements beyond the inherent measurement process.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 approach enhances the reliability of the measurement process, reduces construction and manufacturing efforts, and increases safety by accurately identifying incorrect alignments, thereby preventing fatal measurement errors in blood sugar monitoring.

Implementation Method 1

a photometric measuring unit for recording reflectance measurements on the test field which can be exposed to body fluid

Methodology Applied
Scientific EffectReflectance measurement: Reflection

Data Source

PatentEP2825868B1Test system and method for controlling the alignment of a test strip
Publication Date: 2016.05.04 ROCHE DIAGNOSTICS GMBH
  • EP2825868B1 patent drawingFigure 1~2
  • EP2825868B1 patent drawingFigure 3

AI summary

The invention relates to a test system for analyzing a bodily fluid, in particular for determining the blood glucose level, comprising a test strip (16) which has an analytical test field (22), a photometric measuring unit (28) for detecting remission measurement values on the test field (22) which can be supplied with bodily fluid, a test strip support (14) for orienting the test strip (16) relative to the measuring unit (28), and a control unit (26) for controlling the test strip orientation. According to the invention, the measuring unit (28) detects at least one respective remission measurement value at different wavelengths, and the control unit (26) ascertains a correct or an incorrect test strip orientation by comparing the remission measurement values detected at the different wavelengths with specified reference values.