Bio-sensor Waveguide Coupling Medium for Signal Noise Ratio
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Solution Overview
Problem
Existing bio-sensors using thin-film interferometers face issues with coupling efficiency and alignment due to air gaps, leading to reduced signal-to-noise ratio and increased reflection, making them less effective in detecting analytes in samples.
Innovation Solution
A bio-sensor assembly that eliminates air gaps by using a coupling medium with a refractive index greater than 1.3 between the waveguide and the monolithic substrate, enhancing coupling efficiency and reducing reflections, while a thin-film layer with analyte binding molecules generates spectral interference patterns for analyte detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an air gap is used between the waveguide and monolithic substrate, then alignment is simplified, but coupling efficiency is reduced and reflections increase
Solution Approach 1:
The patent introduces a coupling medium with refractive index between 1.3 and 1.6 as an intermediary substance between the waveguide and monolithic substrate. This coupling medium eliminates the air gap while maintaining simplified alignment, thereby improving coupling efficiency without sacrificing ease of alignment.
2Device complexity
If an air gap is used between the waveguide and monolithic substrate, then the structure is simpler, but signal-to-noise ratio is reduced due to increased reflection
Solution Approach 1:
The coupling medium acts as an intermediary that reduces reflection at the waveguide-substrate interface by providing a gradual refractive index transition. This maintains a simple structural design while significantly improving the signal-to-noise ratio by minimizing unwanted reflections.
3Loss of energy
If a coupling medium with refractive index between 1.3 and 1.6 is used, then coupling efficiency is improved and reflections are reduced, but the system becomes more complex
Solution Approach 1:
The patent optimizes the refractive index parameter of the coupling medium to fall between 1.3 and 1.6, which is matched to the refractive indices of the waveguide and substrate materials. This parameter optimization achieves high coupling efficiency and reduced reflections while keeping the system design straightforward and manufacturable.
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 improves coupling efficiency, minimizes reflections, and simplifies alignment, resulting in enhanced detection capabilities for analytes by maximizing the signal-to-noise ratio and providing accurate kinetic binding curves.
Implementation Method 1
A coupling medium with a refractive index greater than 1.3 between the waveguide and the monolithic substrate, enhancing coupling efficiency and reducing reflections
Implementation Method 2
a thin-film layer with analyte binding molecules generates spectral interference patterns for analyte detection
Data Source
AI summary
The present invention is directed to an assembly for use in detecting an analyte in a sample based on thin-film spectral interference. The assembly comprises a waveguide, a monolithic substrate optically coupled to the waveguide, and a thin-film layer directly bonded to the sensing side of the monolithic substrate. The refractive index of the monolithic substrate is higher than the refractive index of the transparent material of the thin-film layer. A spectral interference between the light reflected into the waveguide from a first reflecting surface and a second reflecting surface varies as analyte molecules in a sample bind to the analyte binding molecules coated on the thin-film layer.