Interferometric Nanoparticle Detection Using Pixel-Diversity Imaging
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Solution Overview
Problem
Existing nanoparticle detection techniques, such as single-particle interferometric reflectance imaging sensor (SP-IRIS), require multiple image acquisitions at different focal positions (z-stacks) due to z-scan measurements, which are time-consuming and computationally intensive, limiting their practical application.
Innovation Solution
The pixel-diversity IRIS (PD-IRIS) method encodes optical signatures of nanoparticles within a single image frame using cameras with filters or pixels sensitive to multiple light components, eliminating the need for z-stack acquisitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If z-scan measurements with multiple frames at different focal positions are used, then sensitivity for nanoparticle detection is improved, but acquisition time and computational processing power requirements increase
Solution Approach 1:
The patent introduces pixel diversity across multiple spectral bands as an additional dimension for encoding particle information. Instead of acquiring multiple frames at different focal positions (z-dimension), the invention encodes optical signatures within a single focal plane using pixels sensitive to different light components (spectral dimension). This dimensional shift allows particle detection and characterization to occur in a single image frame, eliminating the time-consuming z-scan process while maintaining sensitivity through spectral interference patterns.
Solution Approach 2:
The invention changes the measurement parameter from focal position (z-coordinate) to spectral band. By using pixels that are preferentially sensitive to different light components (different wavelengths or polarizations), the system encodes particle optical signatures in the spectral domain rather than requiring mechanical scanning in the spatial domain. This parameter transformation converts a time-intensive sequential measurement into a simultaneous multi-parameter measurement captured in a single frame.
2Measurement precision
If z-scan measurements with multiple frames at different focal positions are used, then sensitivity for nanoparticle detection is improved, but device complexity and computational processing requirements increase
Solution Approach 1:
The patent replaces the z-scan optical path (requiring focal positioning mechanisms) with a spectral encoding path. The imaging sensor includes pixels with diverse sensitivity to different light components, allowing the system to capture particle optical signatures through spectral interference in a single focal plane. This eliminates the need for complex focal scanning optics while maintaining the interferometric enhancement needed for sensitive particle detection.
Solution Approach 2:
The imaging sensor is designed with pixels that serve multiple functions: they simultaneously detect intensity, encode spectral information, and capture particle optical signatures. This multi-functional pixel design consolidates what would otherwise require separate optical paths or sequential measurements, reducing overall device complexity while maintaining detection sensitivity through the unified sensor architecture.
3Loss of information
If z-scan measurements with multiple frames at different focal positions are used, then optical signature extraction is achieved, but data dimensionality and processing power requirements increase
Solution Approach 1:
The patent transforms the data structure from a temporal sequence of focal-plane images (z-stack) to a spatial-spectral data cube captured in a single frame. Each pixel's response across multiple spectral bands encodes the optical signature information that would otherwise require multiple focal scans. This dimensional transformation reduces processing time by eliminating sequential frame acquisition while preserving the interferometric information needed for particle characterization.
Solution Approach 2:
The invention merges the functions of multiple focal-plane measurements into a single spectral-encoded image frame. By combining spectral sensitivity across pixels with interferometric optical path design, the system captures all necessary optical signature information in one simultaneous measurement rather than requiring separate measurements at different focal positions. This merging reduces data dimensionality from a 4D z-stack to a 3D spectral data cube acquired in a single exposure.
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
PD-IRIS reduces data dimensionality and acquisition/processing time, enabling faster and more efficient nanoparticle detection without the need for complex hardware and extensive computational processing.
Implementation Method 1
generate an image at the imaging sensor based, at least in part, on the light reflected from the target interfering with light scattered from nanoparticles on the target substrate
Implementation Method 2
a silicon dioxide coated silicon chip is used to reflect the incoming illumination light and increase the back scattered light from the target particle
Data Source
AI summary
Aspects of inventive concepts described herein relate to an interferometric reflectance imaging system. The system can include an imaging sensor including pixels that are preferentially sensitive to a plurality of light components; an illumination source configured to emit illumination light along an illumination path, the illumination light including the plurality of light components; and a target including a target substrate configured to support one or more nanoparticles on a surface of the target substrate. The system may be configured to, at a nominal focus position: generate an image at the imaging sensor based, at least in part, on the light reflected from the target interfering with light scattered from nanoparticles on the target substrate; and process the image to detect the nanoparticles on the target substrate.