Autoregressive Model for Ion Mobility Spectrometry Noise Cancellation
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Solution Overview
Problem
Existing systems for measuring substance concentration in exhaled breath using ion mobility spectrometry face challenges in accurately determining characteristic values due to noise and the weak signals present in the parts-per-billion range.
Innovation Solution
The implementation of an autoregressive model to fit and process the recorded data set from ion mobility spectrometry measurements, allowing for the cancellation of noise and the determination of reliable characteristic values from the fitted data set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ion mobility spectrometry is used to detect substance concentration in exhaled breath, then the ability to monitor anesthetic agents is improved, but the measurement precision deteriorates due to noise and weak signals in the parts-per-billion range
Solution Approach 1:
The patent applies preliminary action by fitting an autoregressive model to the recorded data set before determining characteristic values. This preprocessing step predicts and removes noise components from the signal, thereby improving measurement precision while maintaining the ability to monitor anesthetic agents in the parts-per-billion range
2Difficulty of detecting and measuring
If the drift time of ionized components is measured to identify substance concentration, then the detection capability is improved, but the reliability deteriorates because drift time is influenced by multiple factors including temperature, pressure, and applied voltage
Solution Approach 1:
The patent employs feedback by using the fitted data set from the autoregressive model to refine the determination of characteristic values. The model continuously adjusts predictions based on the relationship between drift time and substance concentration, compensating for variations caused by temperature, pressure, and voltage fluctuations, thereby improving reliability while maintaining detection capability
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 enables accurate and reliable estimation of substance concentrations in the exhaled breath, improving the signal-to-noise ratio and allowing for precise monitoring of anesthetic agents like Propofol during anesthesia procedures.
Implementation Method 1
Within ion mobility spectrometry, components of a gas probe are ionized and are injected into a drift chamber. By applying a substantial voltage, for example several hundred volts per centimeter, to the drift chamber, the ionized components are driven towards a detector which is constituted to generate a measurement signal upon arrival of the ionized components
Implementation Method 2
The ionized components encounter an opposing force whilst travelling through the drift chamber, which originates from a drift gas that flows through the same drift chamber, but in an opposing direction, thus effectively presenting an obstacle for the ionized components depending on for example their shape and cross section
Data Source
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AI summary
A system for measuring a substance concentration in the exhaled breath of a patient (4) comprises a measurement apparatus (21) for performing an ion mobility spectrometry measurement of a gas probe of the exhaled breath of the patient to obtain a recorded data set (R) indicative of a drift spectrum (S) relating to the gas probe, and a processor (20) for processing the recorded data set (R) to determine at least one characteristic value relating to the drift spectrum (S) and to output a concentration estimate indicative of the substance concentration in the gas probe. Herein, the processor (20) is constituted to fit an autoregressive model to at least a portion of the recorded data set (R) to obtain a fitted data set (F), wherein the processor (20) is further constituted to determine said at least one characteristic value from the fitted data set (F). In this way a system for measuring a substance concentration in the exhaled breath of a patient is provided which allows for accurate measurements using the ion mobility spectrometry (IMS).