NDIR Glucose Sensor Noise Suppression via Triple-Source Pulsed Reflection
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Solution Overview
Problem
Non-Dispersive Infra-Red (NDIR) sensors face challenges in detecting molecules in liquid phases due to weak absorption by targeted molecules, debilitation of probing energy by liquid background absorption, and interference from scattering and absorption noise, which are not effectively addressed in traditional NDIR methods designed for gaseous phases.
Innovation Solution
The implementation of a triple-source NDIR method using a signal source, an interference source, and a reference source, all pulsed at high frequencies, to suppress scattering and absorption interference noise by ensuring both signal and reference beams encounter the same particle environment, allowing for accurate detection of glucose molecules in liquid samples despite interfering molecules, through a reflection sampling technique.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional NDIR method is used to detect molecules in liquid phase, then the detection can be performed, but the absorption by targeted molecules is weak and scattering noise is significant
Solution Approach 1:
The patent applies periodic action by pulsing the light source at high frequency (at least 10 kHz) to create time-resolved measurement windows. This allows the system to capture scattering events that occur during specific phases of the pulse cycle, separating them from the absorption signal. The periodic pulsing enables discrimination between scattering noise and absorption signal based on their different temporal characteristics.
Solution Approach 2:
The patent segments the detection process into distinct time windows within each pulse cycle. By dividing the measurement into early time window (capturing mostly scattering) and later time window (capturing absorption), the system can subtract the scattering component from the total signal, isolating the absorption signal from the targeted molecules.
2Measurement precision
If NDIR is used to detect molecules in liquid medium, then detection is possible, but liquid background absorption debilitates the probing energy
Solution Approach 1:
The patent changes the wavelength parameter by using multiple wavelengths including a reference wavelength that is not absorbed by the targeted molecule but is absorbed by the liquid background. By measuring at multiple wavelengths and using ratioing or differential analysis, the system compensates for background absorption losses and isolates the signal from the targeted molecule.
Solution Approach 2:
The patent implements feedback by using a reference channel that measures the background absorption independently. This reference measurement feeds back into the calculation to compensate for background losses in the signal channel, allowing the system to maintain accurate measurement despite energy depletion by background absorption.
3Measurement precision
If NDIR technique is used for liquid phase detection, then measurement can be performed, but absorption interference noise from interfering molecules is significant
Solution Approach 1:
The patent applies local quality by selecting specific wavelengths that are locally optimized for different purposes: a signal wavelength within the absorption band of the targeted molecule, reference wavelengths within absorption bands of interfering molecules, and a neutral reference wavelength not absorbed by any molecule. This wavelength-specific approach allows the system to isolate and compensate for interference from specific molecules while measuring the targeted molecule.
Solution Approach 2:
The patent uses reference wavelengths as intermediaries to measure and compensate for interference from unwanted molecules. By measuring absorption at wavelengths specific to interfering molecules and using these measurements as intermediary data, the system can mathematically subtract the interference contribution from the total signal, isolating the targeted molecule's absorption.
4Measurement precision
If triple-source NDIR method with pulsed beams is used, then scattering and absorption noise are suppressed, but device complexity increases
Solution Approach 1:
The patent merges multiple light sources and measurement channels into a single integrated detection system. By combining the signal source, reference sources, and detector into one coordinated system with unified timing and processing, the patent reduces the practical complexity despite the increased number of components. The merging approach allows shared hardware resources and coordinated operation that simplifies the overall system architecture.
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 scattering and absorption interference noise, enabling precise measurement of glucose concentrations in liquids by maintaining the advantages of NDIR technology in liquid phases, similar to its performance in gas phases, and provides a practical glucose sensor design.
Implementation Method 1
The signal source emits radiation at a wavelength which is within a first absorption band of the targeted molecule M, the interference source emits radiation at an interference wavelength which is within a second absorption band of said at least one interfering molecule MJ
Implementation Method 2
Such a method will significantly suppress scattering noise when NDIR technique is used to detect molecules in the liquid phase
Implementation Method 3
suppression of both scattering and absorption interference noise (AIN) via a reflection detection technique
Data Source
AI summary
A glucose sensor measures glucose molecules in vivo through use of NDIR in which scattering noise is reduced and Absorption Interference Noise (AIN) is suppressed with a reflection technique. Electronics are used to provide an output of glucose concentration glucose in a liquid sampling matrix after it has been determined that a calibration curve is valid after signal processing is used to obtain average ratio values for reflected signal/reference channels and interference/reference channel obtained after a pulsed beam from signal, interference and reference sources is directed at an inclined angle to a normal of a spot of the liquid sampling matrix. The signal, interference and reference sources are each pulsed at a preselected frequency of at least N Hz which is sufficiently fast so that a given molecule of glucose or interfering molecule will not pass in and out of the liquid sampling matrix within the preselected frequency.