Planar Waveguide Filter Layer for Particle Exclusion
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Solution Overview
Problem
Existing planar waveguide devices face inefficiencies in light guidance and evanescent field interaction, particularly in particle-containing fluids, where solid particles disrupt accurate measurements, and require pre-filtration, limiting their applicability.
Innovation Solution
A planar waveguide device with a miniaturized filter layer featuring filter openings aligned parallel to the light propagation direction, ensuring selective interaction only through these openings, thereby excluding larger particles and minimizing optical leakage, while supporting optical confinement to enhance precision and versatility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a planar waveguide device is used to interact with particle-containing fluids, then optical interaction with the fluid can be achieved, but solid particles in the fluid disturb or hinder accurate measurements
Solution Approach 1:
The filter layer is segmented into multiple filter openings arranged in a regular pattern, creating discrete interaction zones where only particles smaller than the openings can access the evanescent field. This segmentation physically separates the fluid into particle-excluding regions and particle-accessing regions, eliminating measurement interference from larger particles while maintaining optical interaction capability.
Solution Approach 2:
The filter layer introduces local quality variation by creating regions with different optical and physical properties: areas with filter openings allow evanescent field interaction for small particles/fluid, while areas without openings block particle access. This local differentiation enables selective interaction based on particle size, resolving the contradiction between measurement accuracy and particle interference.
2Measurement precision
If pre-filtration is applied to remove particles before measurement, then measurement accuracy improves, but device complexity and operational requirements increase
Solution Approach 1:
The filtering function is merged with the waveguide structure itself by integrating a filter layer directly onto the waveguide. This combination eliminates the need for separate pre-filtration systems, as the filter openings serve dual purposes: maintaining optical confinement for efficient light guidance and providing size-selective access to the evanescent field for particle-free measurement zones.
Solution Approach 2:
The filter layer performs multiple functions simultaneously: it acts as an optical confinement structure to guide light along the waveguide, serves as a physical filter to exclude particles from the evanescent field interaction zone, and maintains fluid flow pathways. This multi-functionality eliminates the need for separate filtration components, reducing device complexity while improving measurement accuracy.
3Object-affected harmful factors
If the filter openings are made smaller to exclude more particles, then particle interference is reduced, but optical confinement and light guidance efficiency deteriorate
Solution Approach 1:
The filter openings are configured as elongated structures extending in the direction of light propagation rather than as simple transverse slits. This dimensional change allows the openings to be narrow in the dimension perpendicular to light propagation (effectively filtering particles) while being extended in the propagation direction, maintaining sufficient optical interaction area and reducing leakage without compromising particle exclusion capability.
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
Enables precise, non-destructive, and selective interaction with fluids, allowing direct measurements in challenging environments without pre-filtration, improving light guidance and evanescent field efficiency, and expanding applications to particle-containing fluids.
Implementation Method 1
the waveguide layer supports optical confinement, and thus the light is effective hindered from escaping from the waveguide layer
Implementation Method 2
selective interaction with a fluid is obtained by evanescent interaction with the fluid in the filter openings
Implementation Method 3
particles in the fluid are often disturbing for the interaction, e.g. if the potential for interaction is higher for the particles compared to the fluid
Data Source
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AI summary
A planar waveguide device(PWD) for interacting with a fluid (FLD) is disclosed, the planar waveguide device (PWD) comprising -a waveguide layer (WGL)for supporting optical confinement, -a coupling arrangement (CPA) for in-coupling and out-coupling of light into and from the waveguide layer (WGL), -a fluid zone (FZN) for accommodating the fluid (FLD), -a filter layer (FTL) arranged between the fluid zone (FZN) and the waveguide layer (WGL) in an interaction region (IAR) of the waveguide layer (WGL), wherein the filter layer (FTL) comprises filter openings (FOP) arranged to allow the fluid (FLD) to interact with an evanescent field of light guided by the waveguide layer (WGL), wherein the filter openings (FOP) are adapted to prevent particles (PAR) larger than a predefined size from interacting with said evanescent field, wherein the filter openings (FOP) are arranged as line openings having their longitudinal direction in parallel with the direction of propagation (DOP) of light guided by the waveguide layer (WGL). Also, use of the planar waveguide device(PWD)for detecting blood hemolysis and a method of interacting light with a fluid is disclosed.