Multi-path Interferometric Sensor for Simultaneous Analyte Detection
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Solution Overview
Problem
Current refractive index sensors face challenges in accurately measuring changes in the concentration of biological or chemical analytes due to limitations in sensitivity and the ability to simultaneously detect multiple samples.
Innovation Solution
A multi-path interferometric sensor system utilizing asymmetric Mach-Zehnder interferometers and micro-ring resonators with thin sensing branches and reference branches, combined with a single light source and detector, allows for precise measurement of phase shifts caused by analyte concentration changes, enabling simultaneous detection of multiple samples through frequency-based analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single interferometer is used for sensing, then the device structure is simple, but the ability to simultaneously detect multiple samples is limited
Solution Approach 1:
The single interferometer is segmented into multiple independent sensing paths (first sensing path, second sensing path, third sensing path) with different optical path lengths. Each path can detect a different sample simultaneously, transforming a single-function device into a multi-functional sensing system without requiring multiple complete interferometer structures.
Solution Approach 2:
The patent introduces the dimension of optical path length difference as a new degree of freedom. By configuring sensing paths with different lengths (L1, L2, L3) while maintaining the same physical interferometer structure, the system achieves multi-sample detection capability through temporal separation of interference signals based on their distinct path lengths.
2Productivity
If multiple interferometers are used to detect multiple samples, then the detection capability is improved, but the device complexity and number of components increase
Solution Approach 1:
Multiple sensing paths are merged into a single interferometer structure. The patent combines three sensing paths with different optical path lengths within one interferometer, sharing common components such as the light source, beam splitter, and detector. This merging approach maintains high detection capability while minimizing the number of physical components.
Solution Approach 2:
The single interferometer is designed to perform multiple sensing functions simultaneously. By configuring different optical path lengths within the same device, the interferometer can detect multiple different samples (analytes in different channels) at the same time, making the device universal rather than specialized for a single sample.
3Measurement precision
If the optical path length difference between sensing paths is increased, then the phase shift measurement sensitivity is improved, but the device size increases
Solution Approach 1:
The patent introduces dynamic modulation by applying different frequencies (f1, f2, f3) to the sensing paths. This dynamic approach allows the system to encode multiple sensing signals in the frequency domain, enabling differentiation of signals from paths with relatively small optical path length differences, thus achieving high sensitivity without requiring large physical dimensions.
Solution Approach 2:
The sensing paths are modulated with periodic signals at different frequencies. This periodic modulation creates distinct frequency signatures for each path, allowing the detector to resolve and measure phase shifts from multiple paths simultaneously even when the optical path length differences are small, thereby maintaining sensitivity while compacting the device size.
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 enhances the accuracy and reduces variance in analyte concentration estimates by creating multiple modulation frequencies, allowing for compact, efficient sensing of multiple samples with improved sensitivity and reduced noise, particularly suitable for applications in liquid and gas environments.
Implementation Method 1
the phase shift of a signal propagating through the asymmetric interferometer. The interferometers can very accurately measure the resulting phase shift
Implementation Method 2
a change in the effective refractive index (of the cladding of the waveguide). This change in effective refractive index alters the optical path length for the signal
Implementation Method 3
the light source is a VCSEL (vertical-cavity surface-emitting laser)
Implementation Method 4
multiple y-splitters are used to divide the input signal from the single source into an appropriate number of signals
Implementation Method 5
the detector is a photodiode
Implementation Method 6
The interferometers are formed as surface waveguides using any waveguide technology (e.g., silica-on-silicon, silicon, nitride-based, etc.)
Data Source
AI summary
A multi-path interferometric sensor for sensing small changes in the refractive index of sensing arms thereof, such as caused by the presence of an analyte or changes in analyte concentration, is disclosed. The sensor includes a single light source, a single detector, and a plurality of interferometers or a single multi-path interferometer. The various sensing branches within the multi-path interferometric sensor each include a delay having a different length. This results in a different modulation frequency for each interferometer, each of carriers include phase information that correlates to a change in refractive index and, ultimately, analyte concentration. The plural carrier frequencies enable simultaneous detection of multiple samples.