Waveguide Particle Sensor Using Evanescent Field
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Solution Overview
Problem
Current particle sensor devices lack the necessary sensitivity and compactness for quick and accessible detection of small airborne particles, particularly those with diameters of 2.5 µm or less, which interfere with light propagation.
Innovation Solution
A compact particle sensor device is designed with a substrate, photodetector, dielectric, and through-substrate via, where electromagnetic radiation is coupled into and out of waveguides on either side of the via, allowing for enhanced detection of light intensity changes caused by particle interactions with the evanescent field, with adjustable waveguide density and size to optimize selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional particle sensor devices are used, then particle detection is possible, but sensitivity and compactness are insufficient for detecting small airborne particles (2.5 µm or less)
Solution Approach 1:
The waveguide is integrated within the substrate structure, with the through-substrate via passing through the substrate and the waveguide being arranged around it. This nesting approach allows the sensing element to be embedded within the device structure rather than being a separate component, achieving compact integration while maintaining sensitivity for detecting small particles through the evanescent field interaction
Solution Approach 2:
The waveguide traverses the through-substrate via in a vertical dimension, with portions of the waveguide arranged on different sides of the via. This three-dimensional arrangement allows the light path to extend through the substrate thickness, increasing the interaction length with particles in the air flow without increasing the planar footprint of the device
2Measurement precision
If waveguide density and size are increased to enhance sensitivity, then detection capability improves, but device area and complexity increase
Solution Approach 1:
The waveguide is positioned specifically around the through-substrate via where the air flow carrying particles passes through. This localized placement concentrates the evanescent field interaction region exactly where particles are most likely to be present, maximizing detection capability without requiring extensive waveguide structures across the entire device area
Solution Approach 2:
The through-substrate via acts as an intermediary structure that guides both the air flow containing particles and the waveguide in close proximity. This intermediary element facilitates the interaction between light and particles without requiring direct contact or large separation distances, enabling sensitive detection within a compact volume
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 device achieves improved sensitivity and integrability, enabling effective detection of small airborne particles by reducing light intensity noise and enhancing the scattering effect, allowing for chip-scale realization.
Implementation Method 1
A waveguide is arranged in or above the dielectric. Electromagnetic radiation emitted by the source of electromagnetic radiation is coupled into a portion of the waveguide on one side of the through-substrate via. The waveguide traverses the through-substrate via in between.
Implementation Method 2
Such particles interfere with the propagation of light and can be detected by their scattering effect on electromagnetic radiation that is emitted by a light source provided in an optical sensor device.
Implementation Method 3
By determining the absorption of the light in the medium in the microchannel by the detector, ionic species can be detected.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The particle sensor device comprises a substrate (1), a photodetector (3), a dielectric (4) on or above the substrate (1), a source of electromagnetic radiation (5), and a through-substrate via (6) in the substrate (1). The through-substrate via is exposed to the environment, in particular to ambient air. A waveguide (7) is arranged in or above the dielectric so that the electromagnetic radiation emitted by the source of electromagnetic radiation is coupled into a portion (7.1) of the waveguide. A further portion (7.2) of the waveguide is opposite the photodetector, so that said portions of the waveguide are on different sides of the through-substrate via, and the waveguide traverses the through-substrate via.