Integrating Sphere Optical Particle Counter

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Solution Overview

Problem

Traditional optical particle counters (OPCs) are expensive, bulky, and labor-intensive due to high-cost optical components and complex alignment processes, making them unsuitable for efficient micron-sized particulate matter (PM) measurement in a compact and cost-effective manner.

Innovation Solution

A compact optical particle counter design featuring an integrating sphere with a light source, photo-detector, and channels for air inlet and outlet, housed in injection-molded components, which eliminates the need for bulky optical elements and uses a heater for aerosol sample transit, allowing for accurate PM concentration measurement with reduced size and component costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional optical components and alignment processes are used in OPCs, then measurement precision is maintained, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:
ImprovePM concentration measurement accuracyVSAvoidoptical component alignment complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent integrates the light source, integrating sphere, photo-detector, and heater into a single compact module, eliminating the need for separate bulky optical components and complex alignment procedures. This merging maintains measurement precision while significantly reducing device complexity and manufacturing cost.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The compact module serves multiple functions simultaneously: the light source provides illumination, the integrating sphere collects and distributes light, the photo-detector measures scattered light, and the heater maintains temperature. This multi-functionality reduces the number of separate components needed, simplifying the overall device while maintaining measurement accuracy.

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

2Measurement precision

If traditional optical components are used in OPCs, then measurement precision is maintained, but device size and weight increase

Engineering Contradiction:
ImprovePM concentration measurement accuracyVSAvoidOPC device weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

By combining all optical components into a single integrated module, the patent dramatically reduces the overall device weight while maintaining measurement precision. The compact design eliminates the need for multiple separate heavy optical elements and their associated mounting structures.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If traditional optical components and assembly processes are used, then measurement precision is maintained, but manufacturing cost increases

Engineering Contradiction:
ImprovePM concentration measurement accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The integrated module design allows for simplified manufacturing processes with fewer assembly steps. By combining components into a single unit, the patent reduces labor-intensive alignment and calibration procedures, thereby lowering manufacturing costs while maintaining measurement precision.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs cost-effective materials and components in the integrated module, such as standard LED light sources and commercially available photo-detectors, replacing expensive specialized optical components. This approach maintains sufficient measurement precision while significantly reducing manufacturing costs.

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

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 solution provides a cost-effective, small-scale OPC capable of measuring PM concentration with high consistency, suitable for personal monitoring and integration into various devices, while maintaining low power requirements and production costs, enabling efficient air quality data logging and wireless communication.

Implementation Method 1

Particles suspended in the aerosol sample scatter light when hit by the laser beam. The light scattered by the particles hits a photo-detector that converts the scattered light into an electrical signal.

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

The light scattered by the particles hits a photo-detector that converts the scattered light into an electrical signal.

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 3

The heater is arranged to exert a convection force on the aerosol sample entering the integrating sphere and hence supporting its transit through the integrating sphere.

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3356793B1Optical particle counter
Publication Date: 2021.12.08 SENSIRION AG
  • EP3356793B1 patent drawingFigure 1
  • EP3356793B1 patent drawingFigure 2
  • EP3356793B1 patent drawingFigure 3

AI summary

An optical particle counter ( 100 ) includes a light source, an integrating sphere (104), a light stop (105), a photo-detector (106), a channel for air inlet ( 107 ), and a channel for air outlet (108). The light source is arranged to focus the light beam in the center of the integrating sphere (104), The light stop (105) is arranged to stop the light beam after exiting the integrating sphere (104 ). The channels for air inlet (107) and outlet ( 108 ) are configured to allow an aerosol sample to enter the integrating sphere ( 104 ), cross the light beam, and exit.