Breath Sensor NDIR Temperature Compensation Segmentation

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Solution Overview

Problem

Existing breath sensors face challenges in accurately measuring carbon dioxide concentration and respiratory rates due to interference from temperature variations and other environmental factors.

Innovation Solution

The proposed breath sensor employs a non-dispersive infrared (NDIR) technology with a light emitting unit, a first light receiving unit, and an operating unit that includes a second light receiving unit to correct for temperature influences and improve signal accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single light receiving unit is used to measure carbon dioxide concentration, then the device structure is simple, but temperature variations and environmental factors cause measurement errors

Engineering Contradiction:

Improvedevice structureVSAvoidcarbon dioxide concentration measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The light receiving unit is divided into two separate units: a first light receiving unit that receives light through the measurement path and a second light receiving unit that receives reference light. This segmentation allows independent measurement of carbon dioxide concentration and temperature compensation, resolving the contradiction between device simplicity and measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A reference light path is introduced as an intermediary element that provides a baseline measurement unaffected by carbon dioxide absorption. This reference path serves as a mediator to compensate for temperature variations and environmental factors, improving measurement precision without significantly complicating the device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If temperature compensation is implemented using additional light receiving units, then measurement accuracy improves, but device complexity increases

Engineering Contradiction:

Improvemeasurement accuracyVSAvoiddevice structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The second light receiving unit serves multiple functions: it measures reference light intensity for temperature compensation and provides a baseline for comparing carbon dioxide absorption. This multi-functionality allows temperature compensation to be implemented without proportionally increasing device complexity, as the reference path structure is shared with the measurement path.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If baseline calculation uses fixed cut-off frequency, then signal processing is simple, but baseline drift occurs under varying respiratory conditions

Engineering Contradiction:

Improvesignal processing complexityVSAvoidbaseline accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The cut-off frequency for baseline calculation is changed from a fixed value to a dynamic parameter that adapts to varying respiratory conditions. This allows the signal processing system to maintain baseline accuracy across different breathing rates and depths without proportionally increasing processing complexity, as the adaptation follows established algorithms.

Inventive Principle:

Principle #15Dynamics

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

This approach enables more precise measurement of carbon dioxide concentration and respiratory rates by effectively accounting for temperature variations and reducing noise interference, leading to improved accuracy and reliability.

Implementation Method 1

a light emitting unit (16), a first light receiving unit (18)... the operating unit (20) performs an operation on a signal value obtained by the first light receiving unit (18)

Methodology Applied

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

Implementation Method 2

non-dispersive infrared (NDIR) technology

Methodology Applied

Scientific EffectInfrared Radiation: Infrared Radiation

Implementation Method 3

a second light receiving unit (22) to receive the light (14), which did not pass through the measurement path (12)

Methodology Applied

Scientific EffectReference light detection:

Data Source

PatentUS20250035611A1Breath sensor, gas sensor, and breath sensing method

Publication Date: 2025.01.30 ASAHI KASEI MICRODEVICES CORP

AI summary

Provided is a breath sensor which senses a breath generated by breathing, including: a light emitting unit which emits light toward a path through which the breath passes; a first light receiving unit which receives at least a part of the light emitted from the light emitting unit and outputs a first light reception signal according to a light reception result; and an operating unit which performs an operation on the first light reception signal, wherein the operating unit calculates a baseline of a waveform of based on a frequency component of the first light reception signal lower than a first cut-off frequency that is set, and senses the breath based on a signal obtained by removing the baseline from the first light reception signal.