IR Fluid Sensor Using Housing Pulses for Gas Detection

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

There is a need for a fluid sensor that can be produced cost-effectively while maintaining or improving reliability and accuracy, particularly for detecting gases and liquids in environmental atmospheres.

Innovation Solution

A fluid sensor design comprising a housing structure with a cavity, an IR emitter, and an inertial detection sensor, where IR radiation interacts with the target fluid to induce mechanical pulses in the housing structure, which are sensed by the inertial detection sensor, providing both photoacoustic and non-dispersive IR sensing capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional optical sensors (PAS) are used for gas detection, then measurement precision is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvegas detection accuracyVSAvoidsensor structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the infrared emitter and the acceleration sensor into a single integrated sensor unit. The housing structure serves dual purposes: as the measurement cavity for IR radiation interaction and as the mechanical structure for the acceleration sensor. This merging eliminates the need for separate acoustic transducers and complex optical paths, reducing device complexity while maintaining gas detection capability through the inverse relationship between housing heating and target gas absorption.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the conventional acoustic transducer (microphone) with an acceleration sensor that detects mechanical pulses directly. Instead of converting acoustic waves to electrical signals, the system uses IR radiation to heat the housing structure, creating thermal expansion/contraction mechanical pulses that are directly sensed by the acceleration sensor. This substitution simplifies the detection mechanism and reduces device complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If conventional PAS sensors with acoustic transducers are used, then gas concentration detection is achieved, but manufacturing cost increases

Engineering Contradiction:
Improvefluid concentration detectionVSAvoidsensor production cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs an acceleration sensor, which is a relatively inexpensive and widely available component compared to specialized acoustic transducers. The simplified housing structure and integrated design reduce manufacturing steps and material requirements, making the sensor more cost-effective for mass production while maintaining adequate detection precision for environmental monitoring applications.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The housing structure serves multiple functions: it contains the target fluid, conducts IR radiation to create thermal pulses, and acts as the mechanical structure for the acceleration sensor. This multi-functionality reduces the number of separate components needed, simplifying manufacturing and reducing production costs while maintaining detection capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If IR radiation is used to heat the housing structure for detection, then sensor output signal is generated, but energy consumption increases

Engineering Contradiction:
Improvefluid detection signalVSAvoidIR emitter energy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The IR emitter operates in a pulsed or modulated manner rather than continuously, emitting IR radiation at specific intervals or frequencies. This periodic operation reduces overall energy consumption while still generating sufficient thermal pulses in the housing structure for the acceleration sensor to detect fluid concentration changes. The pulsed operation allows the system to accumulate enough thermal effect during each pulse cycle without requiring continuous high energy input.

Inventive Principle:
Principle #19Periodic action

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 sensor achieves accurate and efficient detection of fluid concentrations by inversely proportional output signals based on IR radiation absorption, allowing for real-time monitoring of environmental conditions and potential air pollution.

Implementation Method 1

an IR emitter 18 optically coupled to the housing structure 12 and configured for emitting an IR radiation 20 in the cavity 14, wherein the IR radiation 20 has a center wavelength lambda 0 for providing an interaction of the IR radiation 20 with a target fluid Ft resulting in a temperature change Delta T

Methodology Applied
Scientific EffectInfrared radiation absorption: Absorption (EM radiation)

Implementation Method 2

The sensor achieves accurate and efficient detection of fluid concentrations by inversely proportional output signals based on IR radiation absorption

Methodology Applied
Scientific EffectPhotoacoustic effect: Photoacoustic Effect

Implementation Method 3

a heating of at least a portion of the housing structure 12 which effects a mechanical pulse in of at least the portion of the housing structure 12

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3907491B1Fluid sensor
Publication Date: 2025.12.03 INFINEON TECHNOLOGIES AG
  • EP3907491B1 patent drawingFigure 1
  • EP3907491B1 patent drawingFigure 2
  • EP3907491B1 patent drawingFigure 3

AI summary

A fluid sensor (10) comprises a housing structure (12) forming a cavity (14) for , an IR emitter (18) configured for emitting an IR radiation (20) in the cavity (14), wherein the IR radiation (20) has a center wavelength (λ0) for providing an interaction of the IR radiation (20) with the target fluid (FT) resulting in a temperature change (ΔT) in the cavity (14) or in the housing structure (12) which effects a mechanical pulse (22) in the housing structure (12), and an inertial detection sensor (24) mechanically coupled to the housing structure (12) for sensing the mechanical pulse in the housing structure (12).