FTIR Sensing System with Localized Reference Sites
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Solution Overview
Problem
Existing sensing systems for fluids face challenges in suppressing fluctuations in sensing signals that are not induced by the substance being sensed, particularly due to spatially non-uniform intensity variations, which cannot be effectively eliminated by prior normalization methods.
Innovation Solution
The system employs a frustrated internal reflection (FTIR) technique with strategically arranged sensing and reference sites, where the reference signal is not influenced by the substance or fluid, and the sensing signal is dependent on the substance, with the sensing and reference sites optimized to ensure that drift variations of the normalized signal are within noise variations, reducing the impact of spatially non-uniform fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference site is used for normalization to suppress fluctuations, then common-mode intensity variations are reduced, but spatially non-uniform fluctuations remain and cannot be eliminated
Solution Approach 1:
The optical interface is divided into multiple sensing sites and reference sites. Each sensing site has its own dedicated reference site, allowing localized normalization that accounts for spatially non-uniform fluctuations. This segmentation enables independent correction of intensity variations at different spatial locations, thereby eliminating the limitation of global normalization.
Solution Approach 2:
Each sensing site is paired with a specific reference site to perform local normalization rather than global normalization. This local quality approach ensures that the normalization process accounts for spatially varying intensity fluctuations specific to each location, thereby improving measurement precision while maintaining signal stability.
2Measurement precision
If multiple reference sites are used to improve normalization accuracy, then spatially non-uniform fluctuations can be suppressed, but device complexity increases
Solution Approach 1:
The system segments the optical interface into sensing sites and reference sites, with each sensing site having a dedicated reference site. This segmentation provides a systematic approach to using multiple reference sites while maintaining organizational simplicity and reducing the complexity of managing numerous reference sites.
Solution Approach 2:
Each reference site acts as an intermediary that provides local intensity reference information for its corresponding sensing site. This intermediary approach simplifies the normalization process by providing localized reference points, thereby improving measurement precision without requiring complex global normalization algorithms.
3Measurement precision
If sensing and reference sites are placed close together, then spatially non-uniform fluctuations are reduced, but the area available for sensing decreases
Solution Approach 1:
The optical interface is segmented into multiple small sensing sites and reference sites. This segmentation allows the system to use multiple distributed reference sites across a larger total area, thereby maintaining adequate sensing area while achieving spatial uniformity through local normalization at each segmented site.
Solution Approach 2:
Instead of placing reference sites only adjacent to sensing sites in one dimension, the system distributes reference sites across the optical interface in multiple dimensions. This dimensional approach increases the total sensing area available while maintaining spatial uniformity through multi-dimensional reference site distribution.
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 significantly reduces the influence of spatially non-uniform fluctuations, improving the accuracy of the normalized sensing signal by ensuring that drift variations are minimized within noise variations, leading to more reliable substance detection in fluids.
Implementation Method 1
A magneto-optical biosensor for detecting magnetic beads at several binding spots on an optical interface using frustrated total internal reflection (FTIR) can be used as a sensing system for sensing a substance in a fluid. For performing FTIR light from a light source is directed onto the optical interface such that an evanescent field is generated at the binding spots.
Implementation Method 2
For performing FTIR light from a light source is directed onto the optical interface such that an evanescent field is generated at the binding spots. The magnetic beads at the binding spots influence the evanescent field, wherein this influence is detected as intensity variations in the light reflected from the optical interface.
Implementation Method 3
The magnetic beads at the binding spots influence the evanescent field, wherein this influence is detected as intensity variations in the light reflected from the optical interface. By binding or non-binding of these magnetic beads to the optical interface in a biological assay, the presence of various substances, e.g. drugs-of-abuse or cardiac troponin-I, are detected in real matrices like saliva or blood by detecting the magnetic beads, which have attached the substances, within the evanescent field.
Data Source
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AI summary
The invention relates to a sensing system for sensing a substance in a fluid. The sensing system comprises a sensing site (132) at which the substance is to be sensed and a reference site (131). A signal generation unit generates a sensing signal by sensing the sensing site (132) and a reference signal by sensing the reference site (131). The reference signal is used for normalizing the sensing signal, wherein the sensing site (132) and the reference site (131) are arranged such that a drift variation of the normalized sensing signal is within a noise variation of the normalized sensing signal. This improves the accuracy of the normalized sensing signal.