Filterless NDIR Sensor Using NIREM Emitter

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Solution Overview

Problem

Existing non-dispersive infrared (NDIR) gas sensors are limited by the need for expensive narrow bandpass filters and can only operate at a single fixed frequency, making them costly and complex.

Innovation Solution

A nanophotonic infrared emitting metamaterial (NIREM) emitter is used in conjunction with a broadband detector to selectively emit radiation corresponding to specific vibrational resonance frequencies of different analytes, eliminating the need for filters and enabling multifrequency operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a narrow bandpass filter is used in conventional NDIR sensors, then the sensitivity and selectivity are improved, but the cost and device complexity increase significantly

Engineering Contradiction:

ImprovesensitivityVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes the narrow bandpass filter from the conventional NDIR sensor system. Instead of using a filter to select the detection frequency, the system uses a broadband detector combined with a frequency-modulated broadband light source, eliminating the filter component entirely while maintaining measurement precision through alternative spectral selection methods.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The broadband detector serves multiple functions: it detects multiple frequencies simultaneously, works with frequency-modulated light sources, and enables both single-frequency and multi-frequency operation modes. This universal detector replaces the specialized narrow-band detector traditionally paired with filters, reducing system complexity while maintaining sensitivity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If a narrow bandpass filter is used in conventional NDIR sensors, then the measurement precision is improved, but the manufacturing cost increases

Engineering Contradiction:

ImprovesensitivityVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent removes the expensive narrow bandpass filter from the optical path. The filterless design eliminates a major cost driver in conventional NDIR sensors, making the system more manufacturable while maintaining sensitivity through the combination of broadband source and frequency-modulated detection.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system changes the operational parameters by using frequency modulation of the broadband light source instead of fixed-frequency operation with filters. This parameter change enables the use of cheaper broadband components while achieving the same measurement precision through temporal frequency discrimination rather than spatial spectral filtering.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If a filter wheel with multiple bandpass filters is employed to enable multifrequency operation, then the adaptability is improved, but the device complexity and size increase significantly

Engineering Contradiction:

Improvemultifrequency operationVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The broadband detector combined with frequency-modulated broadband light source provides universal detection capability across multiple frequencies simultaneously. A single optical path and detector can measure multiple gas species at different frequencies without mechanical filter wheels, enabling multifrequency operation while dramatically reducing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces the mechanical filter wheel system with an electronic frequency modulation approach. Instead of mechanically switching between filters, the system uses electronic modulation of the light source frequency and synchronous detection, eliminating moving parts and mechanical complexity while enabling rapid multifrequency switching.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If a filter wheel with multiple bandpass filters is employed to enable multifrequency operation, then the adaptability is improved, but the device size increases

Engineering Contradiction:

Improvemultifrequency operationVSAvoiddevice size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent extracts and removes the bulky filter wheel assembly from the device. The filterless design with broadband components and electronic frequency modulation eliminates the need for large mechanical structures, significantly reducing device volume while maintaining the ability to operate at multiple frequencies.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The mechanical filter wheel is replaced with an electronic frequency control system. This substitution eliminates the need for large mechanical components and allows for compact integration of multifrequency capability within a small form factor, as frequency switching is achieved electronically rather than mechanically.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 NIREM-based NDIR sensor achieves similar sensitivity to commercial NDIR devices without the requirement of a bandpass filter, offering a cost-effective and compact solution for detecting gases like CO2.

Implementation Method 1

Methodology Applied

Scientific EffectMetamaterial resonance:

Implementation Method 2

selectively emit radiation corresponding to specific vibrational resonance frequencies of different analytes

Methodology Applied

Scientific EffectVibrational resonance: Resonance

Implementation Method 3

This can be achieved through exploitation of the Beer-Lambert law demonstrating that a reduction in the transmission of IR light resonant with a molecular vibrational absorption over a defined cross-sectional area and path length is directly proportional to the concentration of that molecule in the gas cell

Methodology Applied

Scientific EffectAbsorption spectroscopy: Absorption Spectroscopy

Implementation Method 4

exploitation of the Beer-Lambert law demonstrating that a reduction in the transmission of IR light resonant with a molecular vibrational absorption

Methodology Applied

Scientific EffectBeer-Lambert law:

Implementation Method 5

These devices utilize a broadband IR emitter, thermopile detector and a spectrally narrow bandpass filter

Methodology Applied

Scientific EffectThermopile effect: Seebeck Effect

Data Source

PatentUS12209949B2Filterless non-dispersive infrared sensing devices and methods

Publication Date: 2025.01.28 THIRD FLOOR MATERIALS INC

AI summary

Devices and methods for non-dispersive infrared (NDIR) sensing are disclosed. In one aspect, a non-dispersive infrared sensor is disclosed which, in one embodiment includes a nanophotonic infrared emitting metamaterial (NIREM) emitter configured to selectively emit radiation corresponding to a respective vibrational resonance frequency for each of a plurality of different analytes of interest. The broadband detector can be configured to detect photons associated with vibrational resonance of each of the plurality of analytes of interest in response to the emitted radiation from the NIREM emitter, in order to determine properties of one or more of the analytes of interest.