LSPR Spectral Image Contrast for Low-LOD Microfluidic Detection
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Solution Overview
Problem
Current LSPR immunoassays face challenges in improving sensitivity and pushing the limit of detection (LOD) due to low figure of merit (FoM) and require significant object loading for color change detection, limiting their effectiveness in biomolecular sensing.
Innovation Solution
A detection method and system that utilizes spectral image brightness contrast by calculating the difference between long and short wavelength bands in LSPR images of flowing reporters in a microfluidic chip, setting a threshold for spectral image brightness contrast (γ) to enhance sensitivity and LOD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UV-Vis absorption spectrum method is used to detect LSPR peak shift, then detection can be performed with simple equipment, but the limit of detection is restricted due to low figure of merit and tiny peak shift
Solution Approach 1:
The patent transitions from conventional UV-Vis absorption spectrum detection to spectral image brightness contrast detection. This dimensional change involves capturing spatial distribution information of LSPR signals across multiple reporters simultaneously, rather than measuring bulk absorption. The spectral image approach divides the detection into wavelength bands (short and long wavelength) and calculates brightness contrast, enabling detection of tiny LSPR peak shifts at the single nanoparticle level, thus achieving four to seven orders of magnitude improvement in limit of detection without requiring high concentrations of objects of interest
Solution Approach 2:
The patent segments the LSPR spectral information into distinct wavelength bands (short wavelength band and long wavelength band) for individual reporters. By dividing the spectral range and analyzing brightness contrast between these segments, the method can detect subtle LSPR peak shifts that occur when objects of interest bind to reporters. This segmentation approach transforms the undetectable tiny peak shift into a measurable brightness contrast signal, resolving the contradiction between simple detection and high sensitivity
2Ease of operation
If naked eye or lateral flow assay method is used to detect color change, then the method is simple and low cost, but it requires high level of objects of interest loaded on reporters to present significant color changes
Solution Approach 1:
The patent replaces subjective color change assessment with objective spectral image brightness contrast measurement. Instead of relying on human visual detection of color changes that require high analyte concentrations, the system captures spectral images across wavelength bands and calculates quantitative brightness contrast values. This dimensional transformation from visual color assessment to quantitative spectral analysis maintains operational simplicity while enabling detection at four to seven orders of magnitude lower concentrations
Solution Approach 2:
The patent replaces the mechanical/visual assessment system (naked eye observation of color changes) with an optical detection system that captures and analyzes spectral images. The brightness contrast calculation automatically quantifies the LSPR signal changes, eliminating the need for high object loading that was previously required to produce visually detectable color changes. This substitution maintains ease of operation while dramatically improving sensitivity
3Measurement precision
If UV-Vis method is used without signal amplification, then the detection process is straightforward, but the limit of detection remains inferior (ng to μg mL−1)
Solution Approach 1:
The patent achieves superior limit of detection without signal amplification by transitioning to spectral image brightness contrast detection. This approach captures spatial and spectral information simultaneously, enabling detection at the single nanoparticle level. The brightness contrast calculation between short and long wavelength bands amplifies the signal from tiny LSPR peak shifts, achieving four to seven orders of magnitude improvement in limit of detection while maintaining a relatively simple detection system that does not require complex signal amplification mechanisms
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
The method achieves a significantly lower LOD, improving sensitivity by four to seven orders of magnitude compared to UV-Vis and naked-eye assays, with a quick response time and broad dynamic range, suitable for label-free detection of biomolecules and pesticides.
Implementation Method 1
Local surface plasmon resonance (LSPR) is a particular surface plasmon resonance triggered by electromagnetic illumination. A coherent oscillation of free electrons occurs on the surface of plasmonic nanoparticles (hereinafter referred to as NPs), such as gold and silver nanoparticles (Au, Ag NPs).
Implementation Method 2
the LSPR of reporter 91 shows a resonance peak in the visible wavelength regime, noticeable light scattering or absorption is present
Implementation Method 3
the peak resonance wavelength is related to the surface refractive index of plasmonic NPs
Data Source
AI summary
A detection method and a detection system for detecting objects of interest attached to a surface of a plurality of reporters, wherein the plurality of reporters are flowing in a microfluidic chip and illuminated by a light source. The detection method has following steps: obtaining a plurality of local surface plasmon resonance (LSPR) spectral images of each the plurality of the reporters individually, wherein each of the LSPR spectral images has a brightness of a long wavelength band (BA) and a brightness of a short wavelength band (BB); calculating a spectral image brightness contrast γ for each of the LSPR spectral images, whereinγ=BA-BBBA+BB;and, defining a positive threshold for |γ|≥0.1.