Composite Fabry-Pérot Sensor Depth Offset
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Solution Overview
Problem
Existing Fabry-Pérot sensors face challenges in accurately measuring changes in polymer thickness and refractive index due to variations in polymer layer thickness and refractive index, especially when used in arrays, leading to inconsistent detection sensitivities and difficulties in achieving optimal detection conditions across multiple sensors.
Innovation Solution
A self-referencing composite Fabry-Pérot cavity sensor is developed, featuring two juxtaposed cavities with a predetermined depth offset, allowing precise measurement of thickness and refractive index changes regardless of the polymer thickness, using a dielectric material with three reflection surfaces and a method to calculate the change in refractive index (Δ(nt)) independently of the polymer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single Fabry-Pérot cavity sensor is used, then the device complexity is low, but the measurement precision is insufficient due to variations in polymer layer thickness and refractive index
Solution Approach 1:
The sensor is divided into two separate Fabry-Pérot cavities (first cavity and second cavity) with different depths. Each cavity provides an independent measurement path, allowing the system to differentiate between signals caused by analyte interaction and those caused by variations in polymer layer thickness or refractive index, thereby improving measurement precision without requiring a single complex sensor structure
Solution Approach 2:
The patent introduces a reference cavity (second cavity) that acts as an intermediary element. This reference cavity experiences the same environmental conditions and polymer layer variations as the sensing cavity but provides a baseline measurement that can be used to compensate for thickness and refractive index variations, enabling accurate measurement of analyte-induced changes
2Reliability
If polymer layer thickness is varied to optimize detection, then the detection sensitivity improves, but the manufacturing precision becomes difficult to control
Solution Approach 1:
The patent employs cavities with different fixed depths (first depth and second depth) that are offset by a predetermined distance. This dynamic structural design allows the system to accommodate variations in polymer layer thickness while maintaining consistent detection performance, as the depth offset provides a reference that compensates for manufacturing variations in the polymer layer
3Adaptability or versatility
If a single cavity depth is used, then the manufacturing precision is simplified, but the adaptability is reduced due to inability to detect at various wavelengths and incident angles
Solution Approach 1:
The sensor structure is segmented into two cavities with different depths, creating multiple optical paths with different characteristics. This segmentation enables the system to detect at various wavelengths and incident angles by utilizing the different depth offsets, thereby improving adaptability while keeping each individual cavity structure relatively simple
Solution Approach 2:
The dual-cavity structure provides multi-functionality by enabling the sensor to operate effectively at different wavelengths and incident angles. The first cavity with deeper depth and the second cavity with shallower depth work together to provide universal detection capability across various sensing conditions, making the sensor adaptable to different analytical applications
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 accurate and flexible vapor quantitation with a larger dynamic range, allowing for detection at various wavelengths and incident angles without the need for precise quadrature interrogation, and maintains high sensitivity and low detection limits.
Implementation Method 1
Fabry-Pérot based structures can be used to detect a variety of optics and measurements, as well as for determining strain, temperature, acoustic waves, and various other properties and physical parameters
Implementation Method 2
An interference spectrum resulting from light reflecting through the sensor produces a first reflectivity from the first reflection surface, a second reflectivity from the second reflection surface, and a third reflectivity from the third reflection surface
Implementation Method 3
The composite Fabry-Pérot cavity sensor is able to detect a change in thickness and refractive index of a dielectric material upon exposure to a sample
Data Source
AI summary
A self-referencing composite Fabry-Pérot cavity sensor, including methods of use and manufacture. The cavity sensor comprises a substrate defining a first cavity portion juxtaposed to a second cavity portion. The first and second cavity portions are provided having a predetermined depth offset. A polymer or other dielectric material is disposed within the first and second cavity portions. An interference spectrum resulting from a light source of a known wavelength is reflected through the sensor and produces a first refractive index from the first cavity portion offset by a second refractive index from the second cavity portion. The difference in refractive indices can be used to determine various physical parameters. An optical sensor according to the present technology may be used with vapor sensing, pressure sensing, protein detection, photo-acoustic imaging, and the like.