Waveguide Integrated Lens Evanescent Field Uniformity
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Solution Overview
Problem
Existing waveguide systems for fluorescence-based assays face challenges in achieving uniform evanescent field strength and cost-effectiveness, particularly in disposable clinical devices, due to the need for precise alignment and high manufacturing costs of single-mode planar waveguides, and the variability of multimode waveguides leading to spatially varying field strengths.
Innovation Solution
A waveguide with an integrated lens is proposed, where a collimated laser beam is offset and refracted into the waveguide at an angle close to the critical angle for total internal reflection, allowing for uniform evanescent field generation and reduced sensitivity to misalignment, with a second lens for bidirectional light coupling and a fluidic chamber design that separates the waveguide-chamber contact from the optical path to minimize optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If single-mode planar waveguides are used to generate strong evanescent fields, then illumination intensity is improved, but manufacturing precision and cost increase due to strict thickness tolerances
Solution Approach 1:
The patent employs multimode waveguides with relaxed manufacturing tolerances suitable for disposable clinical devices, sacrificing the strong evanescent field of single-mode waveguides for cost-effectiveness and ease of manufacture. The waveguide thickness is not strictly controlled, enabling injection-molding production of disposable cartridges.
Solution Approach 2:
The patent changes the waveguide operating parameters by using multimode operation instead of single-mode, and introduces an integrated lens to focus light at a specific depth within the sample. This allows uniform evanescent field generation across a larger area without requiring precise waveguide thickness control.
2Ease of manufacture
If multimode waveguides are used for easier light coupling and lower cost, then ease of manufacture is improved, but uniformity of evanescent field deteriorates due to spatially varying field strength
Solution Approach 1:
The patent incorporates an integrated lens (cylindrical or spherical) into the waveguide structure to focus the incident light at a specific depth within the sample. This curvature element transforms the divergent multimode input into a focused beam that generates a more uniform evanescent field across the illumination area, eliminating the spatially varying field strength problem.
Solution Approach 2:
The integrated lens acts as an intermediary element between the light source and the waveguide sample interface. It mediates the light coupling process by focusing the incident beam to a specific depth, thereby creating uniform evanescent field conditions despite the inherent variability of multimode waveguide operation.
3Use of energy by moving object
If precise alignment is used to achieve efficient light coupling, then light coupling efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the lens and waveguide into a single integrated component, eliminating the need for separate alignment of lens and waveguide elements. The lens is formed as part of the waveguide structure itself (or as a molded feature in the same plastic cartridge), automatically ensuring optimal alignment between the light coupling interface and the waveguide core.
Solution Approach 2:
The integrated lens structure provides self-alignment functionality, where the geometric relationship between the lens focal point and the waveguide interface is fixed by the manufacturing process itself. This eliminates the need for external alignment mechanisms or procedures, making the device robust against misalignment while maintaining high coupling efficiency.
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 configuration provides a robust, cost-effective, and alignment-insensitive solution for sample illumination, ensuring uniform evanescent field strength and efficient light coupling, suitable for disposable clinical devices and multicolor fluorescence assays, while allowing for flexible adjustment of the incident angle without requiring new waveguide components.
Implementation Method 1
a collimated laser beam is offset and refracted into the waveguide at an angle close to the critical angle for total internal reflection
Implementation Method 2
allowing for uniform evanescent field generation and reduced sensitivity to misalignment
Implementation Method 3
In the lower index material, the light intensity exponentially decays with distance from the surface. This exponentially decaying field - known as an 'evanescent field'
Implementation Method 4
A waveguide with an integrated lens is proposed, where a collimated laser beam is offset and refracted into the waveguide at an angle close to the critical angle for total internal reflection, allowing for uniform evanescent field generation
Data Source
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AI summary
A sample can be illuminated for analysis using apparatus including a light source, a planar waveguide, and a refractive volume. The light source provides light along a propagation vector. The planar waveguide is oriented such that the propagation vector is perpendicular to the normal vector of the planar waveguide and offset from the planar waveguide in a direction parallel to the normal vector of the planar waveguide. The refractive volume is positioned proximate to the planar waveguide and can optically coupling light provided by the light source to the planar waveguide.