Exhaled Air Analysis Device Humidity Calibration

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Solution Overview

Problem

Existing analysis devices for monitoring anesthesia during medical interventions face challenges with high relative humidity in exhaled air, leading to unreliable and non-continuous measurement results, as they require several days to stabilize and provide only quantitative measurements.

Innovation Solution

The analysis device incorporates a multi-capillary column for pre-separation and an ion mobility spectrometer, calibrating signal deflections from analytes to those caused by humidity, allowing for immediate and continuous proportional measurements by determining the ratio of analyte signal deflections to humidity-related deflections, even with increasing absolute values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional ion mobility spectrometers are used to analyze exhaled air, then chemical substances can be detected, but the high relative humidity of exhaled air causes signal interference and unreliable measurement results

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidhumidity interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by dividing the analysis into two distinct separation stages: first, a multi-capillary column performs pre-separation of gas components based on their different passage times (retention time); second, the ion mobility spectrometer performs further separation based on drift time. This segmented approach allows the analyte signal to be distinguished from humidity interference by their different temporal and mobility characteristics, thereby improving measurement accuracy despite high humidity in exhaled air.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an additional separation dimension by combining retention time (from the multi-capillary column) with drift time (from the ion mobility spectrometer). This two-dimensional separation space allows for better discrimination between the analyte signal and humidity-related signals, as they exhibit different patterns in both time dimensions, thus resolving the humidity interference problem.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Loss of time

If the analytical device is used immediately after switching on, then immediate measurements are possible, but the signal amplitudes are continuously increasing and not yet stabilized

Engineering Contradiction:
Improvestabilization timeVSAvoidsignal stability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent applies preliminary action by performing calibration immediately after device startup using a known analyte concentration. The device establishes a reference relationship between signal amplitude and analyte concentration before actual measurements begin. This preliminary calibration allows the system to compensate for the continuously increasing signal amplitudes that occur during the first few days of operation, enabling reliable measurements to be taken immediately without waiting for signal stabilization.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback through continuous calibration measurements using a reference analyte concentration. The system continuously monitors the signal amplitude and adjusts the quantification based on the current signal level, compensating for the drift that occurs during the first few days of operation. This feedback mechanism ensures that accurate measurements can be taken immediately after startup despite the尚未 stabilized signal amplitudes.

Inventive Principle:
Principle #23Feedback

3Productivity

If quantitative measurements are performed immediately, then measurement speed is improved, but the measurements are not yet reliable due to unstable signal amplitudes

Engineering Contradiction:
Improvemeasurement speedVSAvoidquantification accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by performing a calibration measurement immediately after device startup using a known analyte concentration. This calibration establishes the relationship between signal amplitude and analyte concentration before actual patient measurements begin. By performing this preliminary calibration, the system enables immediate quantitative measurements with accurate quantification, eliminating the need to wait several days for signal stabilization while maintaining measurement reliability.

Inventive Principle:
Principle #10Preliminary action

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

Enables reliable, exact, and repeatable continuous monitoring of anesthetic levels in exhaled air immediately after startup, overcoming the limitations of previous devices by using known and constant humidity levels to calculate analyte proportions, thus facilitating real-time anesthesia monitoring.

Implementation Method 1

A multi-capillary column is a gas chromatographic column consisting of numerous bundled individual capillaries that retain different analytes for varying lengths of time

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

A multi-capillary column is a gas chromatographic column consisting of numerous bundled individual capillaries

Methodology Applied
Scientific EffectGas chromatography: Chromatography

Implementation Method 3

an ion mobility spectrometer in which gas components of the exhaled air are ionized and accelerated towards a detection device

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 4

This is achieved using an ion source, such as radioactive nickel

Methodology Applied
Scientific EffectRadioactive decay: Radioactive Decay

Implementation Method 5

The acceleration of the ions in the ion mobility spectrometer is achieved by means of an electric field

Methodology Applied
Scientific EffectElectric field: Electric Field

Implementation Method 6

ions pass through a barrier grid and are accelerated in a drift chamber section of the ion mobility spectrometer

Methodology Applied
Scientific EffectLorentz force: Lorentz Force

Implementation Method 7

Ions of different masses or structures reach different drift velocities here, are thereby separated from each other (second separation)

Methodology Applied
Scientific EffectIon mobility:

Data Source

PatentEP3629917B1Analysis device for analyzing expiration air
Publication Date: 2021.07.21 B BRAUN MELSUNGEN AG
  • EP3629917B1 patent drawingFigure 1~2
  • EP3629917B1 patent drawingFigure 3~5

AI summary

The invention relates to an analysis device (2) for analyzing expiration air of a patient (8), preferably for monitoring a patient under anesthesia during a medical intervention, the analysis device (2) being configured for determining, in the expiration air, a portion of an analyte contained in the expiration air, having: preferably a multi-capillary column (4) for separating the expiration air to be analyzed; and an ion mobility spectrometer (6) in which gas components of the expiration air are ionized and accelerated toward a detection device (20); the analysis device (2) outputting signal excursions (28, 30) which are created by the ionized gas components of the expiration air which hit the detection device (20), wherein a portion of the analyte which is to be determined and is contained in the expiration air to be analyzed is determined by a calibration of the signal excursion (30) of the analyte to a signal excursion (28) which is caused by the air moisture of expiration air.