Analyte Sensor Multilayer Filter for Optical Signal Discrimination
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Solution Overview
Problem
Current analyte sensors face issues with light saturation and cross-talk due to overlapping spectra of excitation and fluorescent emission, leading to inaccurate readings and data contamination, as existing filters are not effective in filtering light within very narrow bands.
Innovation Solution
The implementation of an analyte sensor with a multilayer filter system, including an absorption filter, a reflective filter, and a transparent layer, and the use of polarized light to separate excitation and emission signals, along with a long illumination indicator that continues to emit light after the excitation source is off, to prevent light contamination and enhance signal discrimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thin film dichroic filters are used to separate excitation and emission light, then light separation is achieved, but light saturation and cross-talk occur due to overlapping spectra
Solution Approach 1:
The filter system is divided into multiple independent layers including a dichroic mirror layer, a long-pass filter layer, and a short-pass filter layer. Each layer performs a specific wavelength filtering function, and their combined effect achieves complete spectral separation. This segmented approach allows the system to handle the overlapping spectra problem by breaking down the filtering task into manageable wavelength ranges.
Solution Approach 2:
The patent employs a composite filter structure combining different types of optical filters (dichroic mirror, long-pass filter, short-pass filter) with distinct optical properties. The dichroic mirror reflects excitation light while transmitting emission light, the long-pass filter blocks residual excitation wavelengths, and the short-pass filter eliminates stray emission light. This composite approach creates a robust filtering system that overcomes the limitations of single-layer filters.
2Measurement precision
If narrow band filtering is implemented to distinguish excitation and emission wavelengths, then signal discrimination improves, but filter performance degrades due to manufacturing limitations
Solution Approach 1:
Instead of relying on a single narrow-band filter that is difficult to manufacture, the patent segments the filtering function across multiple layers with broader bandwidths. Each layer handles a specific portion of the spectrum, and their combination achieves the equivalent of a narrow effective bandwidth. This approach relaxes manufacturing tolerances while maintaining wavelength discrimination capability.
Solution Approach 2:
The patent changes the filtering parameters by using multiple filters with different center wavelengths and bandwidths rather than one filter with a narrow bandwidth. The dichroic mirror operates at the excitation wavelength with a specific cutoff, while the long-pass and short-pass filters have complementary bandwidths. This parameter optimization allows standard manufacturing processes to produce filters with sufficient performance.
3Power
If excitation light intensity is increased to improve signal strength, then fluorescent emission increases, but reflected excitation light causes photodetector saturation
Solution Approach 1:
The patent extracts the harmful reflected excitation light from the detection path using the dichroic mirror, which reflects excitation wavelengths away from the photodetector. The long-pass filter further extracts any residual excitation light that might reach the detector. This extraction of the harmful component allows the system to use high excitation intensity without saturation, as the reflected light is actively removed rather than allowing it to interfere with the measurement.
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 significantly reduces light contamination and improves signal accuracy by allowing for precise detection of analyte-related emissions without interference from excitation light, providing more reliable data readings.
Implementation Method 1
an absorption filter, a reflective filter, and a transparent layer disposed between the absorption filter and the reflective filter
Implementation Method 2
a reflective filter, and a transparent layer disposed between the absorption filter and the reflective filter
Implementation Method 3
when irradiated with excitation light within a certain wavelength range (e.g., light having a wavelength of approximately 378 nm), the indicator molecules fluoresce to emit an amount of light within a wavelength range
Implementation Method 4
the use of polarized light to separate excitation and emission signals
Data Source
AI summary
An analyte sensor incorporates one or more techniques for discriminating between different optical signals. In one embodiment, the sensor includes a photodetector that detects a narrow band optical signal. In another embodiment, the sensor includes a multilayer filter including an absorption filter, a reflection filter, and a transparent layer between the absorption and reflection filters. In another embodiment, the sensor employs an indicator that emits light for a period of time after an excitation source is turned off. In another embodiment, the sensor employs a first indicator that is excited by an excitation light source and a second indicator that is excited by light emitted by the first indicator. The second indicator emits light for a period after the excitation source is turned off. In another embodiment, excitation light is polarized by a first polarizer, and a second polarizer at a photodetector passes only light polarized by the first polarizer.