Comparative Discrimination Spectral Detection for Overlapping Chemical Signatures

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Solution Overview

Problem

Existing chemical sensors face challenges in increasing selectivity while reducing complexity, size, and cost, particularly in identifying chemicals with overlapping spectral signatures in complex backgrounds.

Innovation Solution

The Comparative Discrimination Spectral Detection (CDSD) system employs multiple broadband infrared filters and a high-dimensionality configuration-space method to discriminate between target chemicals and interferents with overlapping spectral signatures, using low-resolution optical filters and a processor to assess geometrical relationships between spectral vectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple high-resolution spectral filters are used to improve chemical identification accuracy, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvechemical identification accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the spectral discrimination problem from spectral dimension (wavelength resolution) to geometric dimension (configuration space). By mapping spectral responses to vectors in a high-dimensional configuration space and using geometric relationships (angles, projections) to distinguish chemicals, the system achieves high identification accuracy without requiring high-resolution spectral filters, thus reducing device complexity while maintaining measurement precision.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If configuration space dimensionality is reduced to simplify computations, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:
Improvecomputational complexityVSAvoidchemical discrimination accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

Instead of reducing configuration space dimensionality as in traditional methods (PCA, LDA), the patent inverts the approach by expanding into a high-dimensional configuration space where each chemical's spectral response across multiple broadband filters is represented as a vector. This inversion allows the system to maintain full discriminatory information while simplifying computations through geometric operations in the expanded space, thereby improving measurement precision without increasing device complexity.

Inventive Principle:
Principle #13The other way round (Inversion)

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

CDSD effectively identifies chemicals with overlapping spectral signatures, providing a computational advantage over existing methods like PCA and LDA, enabling binary outcome detection and relative density estimation, even in spectrally cluttered environments, with high accuracy and low uncertainty.

Implementation Method 1

The radiation source comprises an infrared (IR) illuminator... that emits radiation in the near-infrared (NIR), the mid-wave infrared (MWIR), or the long-wave infrared (LWIR)

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

a plurality of low-resolution optical filters operable for filtering the plurality of radiation beams

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS9857295B2Comparative discrimination spectral detection system and method for the identification of chemicals with overlapping spectral signatures
Publication Date: 2018.01.02 THE UNIV OF NORTH CAROLINA AT CHAPEL HILL
  • US9857295B2 patent drawing
  • US9857295B2 patent drawing
  • US9857295B2 patent drawing

AI summary

A comparative discrimination spectral detection (CDSD) system for the identification of chemicals with overlapping spectral signatures, including: a radiation source for delivering radiation to a sample; a radiation collector for collecting radiation from the sample; a plurality of beam splitters for splitting the radiation collected from the sample into a plurality of radiation beams; a plurality of low-resolution optical filters for filtering the plurality of radiation beams; a plurality of radiation detectors for detecting the plurality filtered radiation beams; and a processor for: receiving a set of reference spectra related to a set of target chemicals and generating a set of base vectors for the set of target chemicals from the set of reference spectra, wherein the set of base vectors define a geometrical shape in a configuration space; receiving a set of filtered test spectra from the plurality of radiation detectors and generating a set of test vectors in the configuration space from the set of filtered test spectra; assessing a geometrical relationship of the set of test vectors and the geometrical shape defined by the set of base vectors in the configuration space; and based on the assessed geometrical relationship, establishing a probability that a given test spectrum or spectra matches a given reference spectrum or spectra.