SPR Sensor Cavities with Dielectric Bed for Field Concentration
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Solution Overview
Problem
Current SPR sensors with nanohole arrays face inefficiencies in detecting biomolecular interactions due to improper positioning of biomolecular receptors, which affects the sensitivity and accuracy of detection.
Innovation Solution
A SPR sensor device with a dielectric substrate and a metal layer featuring cavities that widen from the opening to the bottom, filled with a dielectric bed to reduce the apparent depth and enhance the electric field density, allowing receptors to bind in the strongest electric field region for optimal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If receptors are attached on the sensor surface in conventional SPR sensors, then biomolecular interactions can be detected, but the detection sensitivity and accuracy are reduced due to improper positioning of receptors away from the strongest electric field region
Solution Approach 1:
The patent transitions from a flat 2D sensor surface to a 3D nanostructured surface with cavities having varying depths. This dimensional change allows receptors to be positioned at different depths within the metal layer, specifically placing them at the bottom of cavities where the electric field intensity is maximized, thereby resolving the contradiction between detection sensitivity and structural complexity.
Solution Approach 2:
The patent applies local quality by creating cavities with different depths in the metal layer, where the bottom regions have the strongest electric field. Receptors are selectively positioned in these high-field regions at the cavity bottoms, while other areas maintain different structural properties. This localized optimization improves detection sensitivity without requiring complete restructuring of the entire sensor surface.
2Productivity
If nanohole arrays are used in SPR sensors, then high throughput applications are supported, but the positioning of biomolecular receptors remains improper affecting detection accuracy
Solution Approach 1:
The patent maintains the nanohole array structure for high throughput capability while applying local quality by varying the cavity depths within the array. Each cavity is designed with a specific depth profile that concentrates the electric field at its bottom, ensuring that receptors positioned there experience maximum field intensity. This allows the array to maintain high productivity while achieving improved detection accuracy through localized field optimization.
Solution Approach 2:
The patent enhances the conventional 2D nanohole array by introducing a depth dimension with cavities extending to different depths in the metal layer. This 3D structuring allows receptors to be positioned at optimal depths within the metal layer where electric field intensity is maximized, resolving the contradiction between maintaining high throughput array structure and achieving proper receptor positioning for accurate detection.
3Ease of manufacture
If uniform depth cavities are used in metal layer, then manufacturing is simplified, but electric field density is not maximized at receptor binding sites
Solution Approach 1:
The patent applies local quality by creating cavities with non-uniform depth profiles, specifically designing cavities that widen from opening to bottom with the deepest regions at the center. This localized depth variation concentrates the electric field at specific locations (cavity bottoms) where receptors are positioned, achieving maximum field density without requiring complete restructuring of all cavities. The manufacturing process can selectively create these depth variations using techniques like focused ion beam or selective etching.
Solution Approach 2:
The patent introduces asymmetry in the cavity depth structure, where cavities have varying depths rather than uniform depth throughout. The asymmetric depth profile, with deeper regions at cavity bottoms and shallower regions at openings, creates corresponding variations in electric field distribution. This asymmetric structuring maximizes electric field concentration at receptor binding sites while maintaining overall manufacturing feasibility through controlled fabrication processes.
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 design enhances the sensitivity and accuracy of biomolecular detection by positioning receptors and analytes in the region of strongest electric field, improving the signal-to-noise ratio and enabling high-resolution and high-sensitivity SPR imaging.
Implementation Method 1
the discovery of localized surface plasmon resonance (L-SPR) phenomena and enhanced transmission through metallic subwavelength periodic structures
Implementation Method 2
Each surface-bond electromagnetic wave, which is due to a collective oscillation of free electrons at the metal-dielectric interface, propagates with its highest intensity parallel to this interface and decays exponentially away from this interface
Implementation Method 3
light can excite the resonance of surface plasmons at a metal-dielectric interface if an interface-parallel component of the incident light and a surface-bond electromagnetic wave of the SPR both have matching frequencies and matching wavelengths. In the resonance condition, the incident light is absorbed by the metal-dielectric interface so as to couple with the surface-bond electromagnetic wave
Data Source
AI summary
A sensor device comprises a dielectric substrate (52); and a metal layer (53) on the substrate (52) with at least one array of cavities (54) therein and adapted to support L-SPR, each of the cavities (54) in the metal layer (53) having an opening (56) and a closed bottom (58) and widening from opening to bottom. A bed of dielectric material (62) is provided over the bottom (58) of each cavity (54) to reduce its apparent depth, the bed surface (62) being functionalized to bind to receptor moieties (64). This sensor device is particularly designed for SPR detection, but can be used in other detection techniques.