MEMS PM Concentrator Using Optical Cavity for Particle Focusing
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Solution Overview
Problem
Current PM sensors are expensive, bulky, and lack sensitivity, making them unsuitable for detailed personal exposure measurements, especially in varied locations and for large-scale deployment.
Innovation Solution
An in-line MEMS PM concentrator using a converging optical intensity field within a confocal optical cavity to concentrate airborne particles towards the center of microchannels, enhancing sensor sensitivity and allowing for user-wearable, cost-effective PM monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PM sensors are used, then PM concentration can be measured, but the sensors are expensive and bulky, making them unsuitable for large-scale personal deployment
Solution Approach 1:
The patent embeds an optical cavity within the microchannel structure of the PM sensor. The optical cavity is positioned such that its walls form part of the microchannel structure, creating a nested configuration where the optical measurement component is integrated within the fluid flow path, reducing overall device complexity and size.
Solution Approach 2:
The optical cavity serves multiple functions: it acts as both the measurement chamber for detecting PM concentration and as part of the microchannel structure that guides air flow. This multi-functionality reduces the number of separate components needed, thereby reducing device complexity and cost.
2Measurement precision
If conventional PM sensors are used, then PM concentration can be measured, but the sensitivity is insufficient for detailed personal exposure assessment
Solution Approach 1:
The patent creates a localized region of enhanced optical interaction within the optical cavity where PM particles are concentrated. The cavity geometry and optical path are designed to maximize the interaction between light and PM particles in this specific region, thereby enhancing detection sensitivity for low concentrations of PM.
Solution Approach 2:
The patent introduces an optical dimension to the PM measurement process by using an optical cavity to detect PM concentration. This adds a new measurement dimension (optical absorption/scattering) to the traditional mass-based measurement, enabling detection of much lower PM concentrations with higher sensitivity.
3Volume of moving object
If sensor size is reduced for personal wearability, then portability improves, but sensitivity and measurement capability deteriorate
Solution Approach 1:
By nesting the optical cavity within the microchannel structure, the patent achieves high measurement precision in a compact form factor. The integrated design eliminates the need for separate optical chambers and flow channels, significantly reducing the overall sensor volume while maintaining or enhancing detection sensitivity.
Solution Approach 2:
The patent replaces traditional mechanical PM measurement mechanisms (such as gravimetric methods requiring large sampling volumes) with an optical detection system. This substitution enables high-sensitivity PM detection in a much smaller device volume suitable for personal wearability.
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 significantly increases the sensitivity of PM sensors by orders of magnitude, enabling more accurate personal exposure assessments and reducing power consumption, while being robust and inexpensive for large-scale deployment.
Implementation Method 1
concentrate the PM in the center of the microchannel using a converging optical intensity field within a confocal optical cavity
Implementation Method 2
directed toward the center of the microchannel using an in-plane or out-of-plane optical intensity field
Data Source
AI summary
The present disclosure provides for a system and method of concentrating airborne particles, specifically toward the center of one or more intake channels of PM sensors. The invention provides a simple and cost effective device that, when used in conjunction with a MEMS PM sensor or the like, can increase the sensitivity of said device by orders of magnitude. An in-line MEMS PM concentrator uses a converging optical intensity field to concentrate particulate matter along the center of a longitudinal axis of a microchannel. More specifically, the concentrator is designed to bring in ambient air containing PM through a microchannel and concentrate the PM in the center of the microchannel using a converging optical intensity field within a confocal optical cavity.