Forward Scatter Particulate Matter Sensor Waveguide Design
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Solution Overview
Problem
Existing particulate matter sensors face challenges in accurately detecting smaller size particles due to limited light scattering detection capabilities, often requiring complex signal analysis and larger sizes to achieve effective detection.
Innovation Solution
The design incorporates a waveguide system that directs forward-scattered light towards a photodiode, enhancing the signal intensity by collecting more scattered light, and includes a computing device for analyzing the analog signal, allowing for the detection of smaller particles with a compact and modestly priced sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional light scattering detection is used, then the sensor can detect particulate matter, but smaller size particles cannot be detected accurately due to limited light scattering signal
Solution Approach 1:
The patent transitions from detecting light scattered at 90 degrees (perpendicular to incident light) to detecting forward-scattered light (at small angles near the incident light direction). This dimensional change in detection angle enables sensitive detection of smaller particles that produce weak perpendicular scattering signals, resolving the contradiction between measurement precision and detection reliability for small particles.
Solution Approach 2:
The patent introduces a waveguide as an intermediary component that collects and channels forward-scattered light from particles toward the photodiode detector. This waveguide mediator enables efficient collection of the otherwise difficult-to-detect forward-scattered light, improving both the precision and reliability of small particle detection without requiring complex optical systems.
2Measurement precision
If the sensor is designed to detect smaller particles with higher sensitivity, then measurement precision improves, but device complexity and size increase
Solution Approach 1:
The waveguide serves as a compact intermediary that simplifies the optical path for forward-scattered light collection. Instead of requiring complex lens systems or multiple detectors, the waveguide provides a straightforward mechanism to channel light signals, reducing device complexity while maintaining high measurement precision for small particles.
Solution Approach 2:
The patent replaces complex mechanical optical alignment systems with a waveguide-based light channeling approach. The waveguide's inherent light-guiding properties eliminate the need for precise mechanical positioning of lenses and detectors, simplifying the overall sensor structure while enabling sensitive small particle detection.
3Reliability
If forward scatter detection is implemented, then signal intensity increases for small particles, but the sensor requires compact design for consumer-grade applications
Solution Approach 1:
The waveguide is integrated within the compact sensor housing, with the airflow channel, light source, and photodiode arranged in a nested configuration. The waveguide channels forward-scattered light efficiently through this compact nested structure, maintaining strong signal intensity for small particle detection while keeping the overall sensor volume small enough for consumer-grade air cleaners.
Solution Approach 2:
The waveguide intermediary enables strong signal detection in a compact format by efficiently collecting and directing forward-scattered light over short distances. This mediator component allows the sensor to achieve high reliability for small particle detection without requiring the large physical dimensions that would otherwise be needed for equivalent signal strength.
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 the detection of smaller particles with improved sensitivity and accuracy, generating a stronger signal that allows for enhanced particulate matter concentration determination in ambient air, suitable for consumer-grade air cleaners.
Implementation Method 1
a waveguide configured to direct light from the light source after it passes through the airflow channel and scatters off of particulate matter within the airflow channel
Implementation Method 2
a waveguide configured to direct light from the light source after it passes through the airflow channel and scatters off of particulate matter within the airflow channel
Implementation Method 3
a photodiode configured to receive light scattered by the waveguide
Data Source
AI summary
Embodiments relate generally to systems and methods for detecting particulate matter in the air. A particulate matter sensor may comprise an airflow channel; a light source configured to pass light through the airflow channel; an airflow generator configured to generate airflow into the airflow channel; a waveguide configured to direct light from the light source after it passes through the airflow channel and scatters off of particulate matter within the airflow channel; a photodiode configured to receive light scattered by the waveguide; and a computing device coupled to the photodiode having a processor and a memory storing instructions which, when executed by the processor, determines a mass concentration of particles in the airflow channel based on an output of the photodiode.