Radar Spectroscopy Gas Sensor Cross-Sensitivity

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Solution Overview

Problem

IR-based spectroscopic gas sensors face cross-sensitivity issues due to broadband IR signals that span multiple resonance peaks, leading to reduced accuracy in measuring specific gas concentrations, and are prone to degradation over time.

Innovation Solution

A radar-based spectroscopic gas sensor that transmits radar signals within a narrow frequency range covering a specific gas's resonance peak, reducing cross-sensitivity and using a porous enclosure to enhance signal-to-noise ratio, and optionally combining with IR spectroscopy to correct measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If broadband IR signals are used to measure gas concentration, then multiple gases can be detected, but cross-sensitivity increases and measurement accuracy decreases

Engineering Contradiction:

Improveability to detect multiple gasesVSAvoidgas concentration measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The broadband IR spectrum is segmented into multiple narrow frequency bands, each targeting a specific gas resonance peak. The system uses multiple IR transmitters operating at different frequencies to measure different gases independently, eliminating cross-sensitivity while maintaining multi-gas detection capability.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If broadband IR signals are used to span multiple resonance peaks, then measurement coverage increases, but cross-sensitivity to other gases increases

Engineering Contradiction:

Improvespectral coverage rangeVSAvoidcross-sensitivity to other gases

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

Each IR transmitter is configured to operate at a specific frequency with narrow bandwidth that matches the resonance peak of a target gas. This local frequency specialization ensures that each measurement is highly specific to one gas type, preventing interference from other gases while maintaining comprehensive spectral coverage through multiple transmitters.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If IR-based spectroscopic sensing is used, then gas concentration can be measured, but the sensor degrades over time

Engineering Contradiction:

Improvegas concentration measurement capabilityVSAvoidsensor stability over time

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The system combines radar spectroscopy and IR spectroscopy into a hybrid sensing platform. The radar component provides stable, non-degrading reference measurements that can be used to correct and compensate for drift in the IR component over time, maintaining long-term measurement reliability.

Inventive Principle:

Principle #5Merging (Combining)

4Measurement precision

If narrow frequency range radar signals are used, then cross-sensitivity is reduced, but signal-to-noise ratio decreases

Engineering Contradiction:

Improvespecific gas measurement accuracyVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

A porous enclosure acts as an intermediary structure that enhances the interaction between the radar signal and the target gas molecules. The porous material increases the effective path length and confinement of the signal within the gas sample, thereby improving the signal-to-noise ratio while maintaining the narrow frequency range benefits.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 radar-based sensor provides more accurate and reliable gas concentration measurements with reduced power consumption and increased stability compared to IR-based sensors, and can supplement or correct IR-based measurements to improve overall accuracy.

Implementation Method 1

transmit a first radar signal, associated with a resonance peak corresponding to a first gas, through a space including the first gas

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

the first gas is to absorb a portion of the first radar signal to create a second radar signal

Methodology Applied

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

Implementation Method 3

transmit a first infrared (IR) signal, associated with a second resonance peak corresponding to the second gas, through the space, where the first gas or the second gas to absorb a portion of the first IR signal

Methodology Applied

Scientific EffectAbsorption Spectroscopy: Absorption Spectroscopy

Data Source

PatentUS10215691B2Radar spectroscopy based gas sensor

Publication Date: 2019.02.26 INFINEON TECHNOLOGIES AG

AI summary

A gas sensor includes a transmitter that may transmit a first radar signal, associated with a resonance peak corresponding to a first gas, through a space including the first gas and a second gas. The first gas may absorb a portion of the first radar signal to create a second radar signal. The transmitter may transmit a first infrared (IR) signal, associated with a second resonance peak corresponding to the second gas, through the space. The first gas or the second gas may absorb a portion of the first IR signal to create a second IR signal. The gas sensor may include a controller to determine a concentration of the second gas based on the second radar signal and the second IR signal.