Photonic Band Gap Optical Sensor for Label-Free Detection
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Solution Overview
Problem
Existing surface plasmon sensors face limitations due to chemical reactivity, dielectric loss, and limited wavelength operating range, while microarray technologies suffer from low sensitivity, high background interference, and cross-reactivity.
Innovation Solution
An optical multilayer structure exhibiting a photonic band gap is used, comprising alternating layers of high and low refractive index materials, with a terminating layer to support surface optical modes within the band gap, enabling sensitive detection of biological and chemical entities without the need for fluorescent tags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface plasmon sensors use silver for high surface sensitivity, then sensitivity is improved, but chemical reactivity increases making it unsuitable for most applications
Solution Approach 1:
The patent uses a photonic crystal structure as an intermediary medium to achieve surface sensitivity without direct metal-solution contact. The photonic crystal provides the evanescent field necessary for detection while the terminating layer and sensing layer configuration allows detection of bound analytes without requiring the metal surface to be directly exposed to the sample, thus avoiding chemical reactivity issues
Solution Approach 2:
The patent replaces the traditional metal-based surface plasmon resonance mechanism with a photonic crystal-based surface optical wave resonance mechanism. This substitution eliminates the need for reactive metal surfaces (silver, copper, aluminum) while maintaining the resonant coupling effect necessary for sensitive detection through photonic band gap engineering
2Reliability
If surface plasmon sensors use gold to avoid chemical reactivity, then chemical stability is improved, but sensitivity decreases due to higher dielectric loss and broader resonance
Solution Approach 1:
The patent replaces the metal-based surface plasmon resonance system with a photonic crystal-based surface optical wave resonance system. The photonic crystal structure, composed of dielectric materials with different refractive indices, eliminates dielectric loss inherent in metals while maintaining resonant coupling. This substitution achieves both chemical stability and high sensitivity without the broad resonance problem of gold
Solution Approach 2:
The patent employs a composite photonic crystal structure consisting of multiple alternating layers of high and low refractive index materials. This composite structure creates photonic band gaps that enable sharp resonance features for sensitive detection while using chemically stable dielectric materials instead of reactive metals, thus achieving both reliability and measurement precision
3Ease of manufacture
If fluorescent tags are used in microarray detection, then detection capability is improved, but sensitivity decreases due to low signal-to-background ratio and cross-reactivity
Solution Approach 1:
The patent replaces fluorescent tag-based optical detection with surface optical wave resonance detection. The resonant coupling of light to surface waves at the photonic crystal interface provides a highly sensitive, label-free detection mechanism that directly measures changes in the optical properties caused by analyte binding, eliminating the need for fluorescent labels and their associated background interference and cross-reactivity problems
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 approach provides enhanced sensitivity and avoids the limitations of surface plasmon sensors and microarray technologies, allowing for precise detection of biological entities and chemical changes with high throughput and label-free operation.
Implementation Method 1
surface optical wave resonance in photonic band gap films
Implementation Method 2
optical multilayer structure constructed so as to cause the structure to exhibit a photonic band gap
Implementation Method 3
the light creates an evanescent field that can penetrate through the metal
Implementation Method 4
Surface plasmons are resonantly generated at the angle of incidence at which the wave vector and frequency of the evanescent field match those of surface plasmons at the metal-air interface
Data Source
AI summary
A sensing method and apparatus using photonic band gap multilayered material. Photonic band gap multi-layers are formed from alternating layers of higher refractive index and lower refractive index materials, and may be deposited or disposed on a optically transparent substrate or a reflecting face of a prism. Light is directed into the prism, directed to the photonic band gap multilayer, and reflected out of the prism, where it is captured and analyzed. Various sensor configurations keep light wavelength or coupling angle fixed, while monitoring the change in the other parameter. Also disclosed is a microarray configuration with an array of probe spots placed on one surface of the multilayer, which is mounted on an x-y translation stage.