Optical Molecular Nanowire Sensing for Low-Background Fluorescence
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Solution Overview
Problem
Existing optical sensing technologies face limitations in detection sensitivity due to the density of immobilized recognition molecules on flat surfaces, background fluorescence interference, and challenges in distinguishing bound target molecules from free fluorescent molecules, especially in miniaturized sensors.
Innovation Solution
A nanowire-based sensor system that utilizes near-field coupling of light emitted from the sidewalls of nanowires to enhance detection sensitivity by using a high surface-to-volume ratio and selective excitation, allowing for global excitation and enhanced signal-to-noise ratio without requiring precise laser alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the surface area of the sensor is increased to improve detection sensitivity, then the effective detection area increases, but the optical read-out becomes limited because recognition molecules are located in different focal planes
Solution Approach 1:
The patent transitions from a two-dimensional flat surface to a three-dimensional nanowire array structure. The nanowires extend vertically from the substrate, creating a三维 detection surface that increases effective area while maintaining a unified focal plane for optical detection. This dimensional transformation allows recognition molecules to be distributed across multiple nanowire surfaces while remaining optically accessible from a single focal plane.
2Object-affected harmful factors
If miniaturized sensors are introduced to reduce background fluorescence, then the surface area decreases and background signal is reduced, but the rate of transport by diffusion is compromised and the output signal is reduced
Solution Approach 1:
The patent applies local quality by creating localized high-surface-area regions (nanowire surfaces) that concentrate recognition molecules in specific zones. Each nanowire provides a localized detection zone with high surface-to-volume ratio, maintaining efficient analyte interaction while the overall sensor footprint remains small, thus reducing total background fluorescence.
3Measurement precision
If the density of immobile recognition molecules on a flat surface is increased to improve detection sensitivity, then more target molecules can be detected, but background fluorescence interference increases and it becomes difficult to distinguish bound target molecules from free fluorescent molecules
Solution Approach 1:
The patent segments the detection surface into numerous individual nanowire structures rather than using a continuous flat surface. Each nanowire acts as an independent detection element with its own recognition molecules. This segmentation allows the system to maintain high total recognition molecule density across the array while the vertical geometry and optical collection strategy minimize background fluorescence from unbound molecules.
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 nanowire sensor system achieves improved detection sensitivity and specificity by enhancing the effective detection surface area and filtering out background fluorescence, enabling reliable detection of target molecules in both liquid and gas phases.
Implementation Method 1
A molecular sensor including a nanowire configured to utilize an optical near-field effect to guide light emitted from sidewalls of the nanowire to a free end of the nanowire
Implementation Method 2
a fluorophore attached to the nanowire... irradiating the nanowire with excitation radiation... collect radiation generated by the fluorophore
Data Source
AI summary
An analyte detection system includes a substrate, a nanowire positioned on the substrate, the nanowire configured to bind with an analyte and a fluorophore, an excitation radiation source configured to irradiate the nanowire with excitation radiation, and a radiation detection device configured to collect radiation emitted by the fluorophore and output from the free end of the nanowire. The substrate may be a reflective substrate, a numerical aperture (NA) of the excitation radiation source may be 0.25 or less, and/or the nanowire may have a diameter D=M*λ/[Re(n(λ))], wherein 5.5≤M≤6.5, λ is a peak wavelength of the excitation radiation or a peak wavelength of the collected radiation, and Re(n(λ)) is a real part of a refractive index of the nanowire at peak wavelength λ.