Assay Apparatus Optical Positioning for Misregistration
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Solution Overview
Problem
Existing immunochromatographic assay apparatuses face challenges in accurately positioning the assay region due to individual differences in cartridge manufacturing, leading to misregistration and erroneous determinations, especially when the color development state changes are weak or similar to noise.
Innovation Solution
The assay apparatus includes a light source, an imaging unit, and a processor that detects the position of an index region with a preset interval from the assay region, using optical density or color changes to specify the assay region's position, even in cases of misregistration, by acquiring images under different monochromatic light sources and processing them to distinguish the index region from noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If elastic bodies such as springs are used to bias the test piece to the target position, then positioning accuracy of the light source and light receiving section is improved, but individual differences in cartridge manufacturing still cause misregistration of the assay region
Solution Approach 1:
The patent replaces the mechanical positioning system (springs and elastic bodies) with an optical detection system. The imaging unit captures images of the carrier, and the processor automatically detects the assay region's position through image analysis, eliminating reliance on mechanical biasing components that fail to account for individual cartridge variations.
Solution Approach 2:
The system uses the carrier's own visual features (colored regions with different optical densities) to automatically determine its position. The assay region and control region serve as self-identifying markers that enable the processor to locate and measure the correct regions without external mechanical positioning aids.
2Reliability
If the color development state changes are weak or similar to background noise, then the assay sensitivity is improved, but erroneous recognition occurs due to inability to distinguish assay region from noise
Solution Approach 1:
The patent applies different optical properties to different regions of the carrier. The assay region and control region contain colored substances with specific optical densities that differ from the background membrane and from each other. This local differentiation allows the imaging system to distinguish these regions even when color development is weak, as the underlying optical density differences remain detectable.
Solution Approach 2:
The carrier is pre-prepared with colored regions (assay region and control region) that have distinct optical densities before the assay is performed. This preliminary visual encoding enables the system to pre-identify region boundaries and locations, so that even weak color development during the assay can be accurately attributed to the correct regions without confusion with background noise.
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 allows for accurate specification of the assay region's position, reducing erroneous determinations and improving the reliability of positive or negative sample identification, even with weak color changes or noise presence.
Implementation Method 1
a light source that illuminates an observation region on the carrier including the assay region and the index region
Implementation Method 2
the light receiving section detects the light reflected by or transmitted in the coloration region
Implementation Method 3
the processor is configured to acquire an image including the observation region from the imaging unit, detect a position of the index region from the acquired image
Data Source
AI summary
The assay apparatus includes a loading part into which a cartridge including a carrier and a case is attachably and detachably to be loaded, the carrier having an assay region in which a color development state changes depending on whether the sample is positive or negative, and an index region which is optically distinguishable from other regions regardless of whether a sample is positive or negative, the case accommodating the carrier; a light source that illuminates the observation region on the carrier including the assay region and the index region; an imaging unit that images the observation region; and a processor configured to acquire an image including the observation region from the imaging unit, detect a position of the index region from the acquired image, and specify a position of the assay region with reference to the detected position of the index region.