Sensing Chip Strip Metal Long-Range Plasmon Polariton
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Solution Overview
Problem
Conventional surface plasmon polariton sensors are large, require multiple components, are difficult to adjust, and lack stability, limiting their universalization and application, while long-range surface plasmon polariton sensors offer high precision but have a limited measurement range and are not suitable for practical use.
Innovation Solution
A sensing chip with a strip-like metal structure, a buffer layer, and reference arms, where the metal thin film or strip-like metal is sandwiched between silicon-rich silica or silicon nitride layers, allowing for the measurement of refractive index changes through transmission loss or light spot size, enabling high precision and wide-ranging measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional surface plasmon polariton sensor uses a prism and turntable configuration, then the sensor can measure refractive index changes, but the device becomes large, complex, and difficult to adjust
Solution Approach 1:
The patent replaces the conventional mechanical prism and turntable system with an integrated chip-based structure. The sensing chip incorporates the metal film, dielectric layers, and optical path directly on a substrate, eliminating the need for separate mechanical components like prisms and turntables. This substitution of mechanical systems with an integrated photonic structure reduces device complexity while maintaining refractive index measurement capability through surface plasmon polariton excitation.
Solution Approach 2:
The patent merges multiple functional components into a single integrated sensing chip. The metal film, dielectric buffer layer, measurement layer, and optical excitation path are combined into one compact structure. This integration consolidates what would otherwise require separate prism, turntable, and sensor components into a unified device, reducing overall system complexity and improving adjustability.
2Measurement precision
If a long-range surface plasmon polariton sensor uses a thin metal film structure, then the measurement precision is high, but the measurement range is limited and the structure is not suitable for sealing
Solution Approach 1:
The patent applies different dielectric materials with specific refractive indices to different regions of the sensing chip. The dielectric buffer layer has a refractive index matched to the metal film for optimal surface plasmon polariton coupling, while the measurement layer above it can be customized for specific applications. This local optimization of material properties enables both high measurement precision through proper coupling and extended measurement range through adjustable measurement layer characteristics.
Solution Approach 2:
The patent enables adjustment of the measurement range by changing the thickness and refractive index of the dielectric buffer layer and measurement layer. By modifying these structural parameters, the sensor can be tuned to detect different ranges of refractive index changes while maintaining high precision through the long-range surface plasmon polariton effect. The metal film thickness is also optimized to balance between coupling efficiency and measurement range.
3Measurement precision
If the metal thin film thickness is reduced to form long-range surface plasmon polaritons, then transmission loss decreases and measurement precision improves, but the structure becomes more sensitive to refractive index differences limiting the measurement range
Solution Approach 1:
The patent introduces a dielectric buffer layer as an intermediary between the metal film and the measurement layer. This buffer layer with its specific refractive index acts as a mediator that optimizes the coupling between the metal film's surface plasmon polaritons and the measurement layer. The buffer layer thickness and refractive index are carefully selected to achieve both low transmission loss for high precision and appropriate sensitivity to the measurement layer's refractive index changes for extended measurement range.
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 provides a compact, stable, and cost-effective means to measure refractive indices with high sensitivity, suitable for biological reactions and molecular modifications, and allows for the integration of optical fibers, enhancing practicality and industrial value.
Implementation Method 1
A surface plasmon polariton ((SPP), FIG. 1) is an electromagnetic field transmitted along the interface between a metal and a dielectric, and the amplitude thereof is exponentially attenuated in the dielectric in response to the distance from the interface. The SPP is a kind of surface wave whose electromagnetic field energy is concentrated in the vicinity of the interface between the metal and the dielectric, and hence the electromagnetic field on the metal surface is strong and extremely sensitive to the mode of the surface, particularly a change in the refractive index.
Implementation Method 2
When the thickness of the metal thin film decreases up to a constant degree, the two sets of surface plasmon polaritons are coupled with each other. The electric field distribution of such a coupled wave is mostly concentrated in an upper dielectric 2 and a lower dielectric 6 other than the metal and the coupled wave can be transmitted on the metal surface in a long-range manner with small transmission loss, and hence the same is referred to as long-range surface plasmon polariton (LR-SP).
Data Source
AI summary
There is provided a sensing chip capable of measuring a refractive index by utilizing a long-range surface plasmon polariton, accurately measuring an accumulative refractive index in a wide range, and more easily enabling sealing for measurement. The present invention relates to the sensing chip which has a thin metal film or a strip-like metal grown on an underlayer, and has a dielectric that limits a refractive index and a dielectric buffer layer on an upper surface and a lower surface of the thin metal film or the strip-like metal. The dielectric buffer layer is attached onto the thin metal film or the strip-like metal. The thin metal film or the strip-like metal and the buffer layer are sandwiched between two dielectric layers. A hole is made in a surface of the upper dielectric layer to serve as a measurement groove.