Breath Collection Apparatus with Downstream Gas Sampling
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Solution Overview
Problem
Existing apparatuses for collecting and sampling volatile organic compounds (VOCs) from human breath are inaccurate due to assumptions about lung capacity and expiration rate, lack precision in gas collection, and fail to prevent cross-contamination, with issues such as incomplete sampling and contamination from prior samples.
Innovation Solution
An apparatus with a gas collection and sampling system that includes a gas inlet, exhaust portion with volume and quality measurement devices, and a collection portion with a reciprocating piston for precise gas sampling, allowing for simultaneous gas collection and venting, and the use of thermal desorption tubes to filter out undesired compounds like nitrogen, oxygen, and carbon dioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If assumptions about lung capacity and expiration rate are used for alveolar sampling, then the sampling process is simplified, but measurement precision deteriorates due to inaccuracies when subject parameters deviate from normal assumptions
Solution Approach 1:
The system uses a CO2 monitor to provide real-time feedback on the composition of expired breath, allowing the control system to dynamically adjust sampling timing and duration based on actual breath characteristics rather than fixed assumptions. This feedback mechanism enables accurate identification of the alveolar phase by monitoring CO2 concentration changes during expiration.
Solution Approach 2:
The sampling system transitions from static, assumption-based timing to dynamic, real-time adjustment of sampling parameters. The system continuously monitors breath flow rate and CO2 concentration, adapting the sampling window to match the actual expiration profile of each subject, thereby maintaining precision across diverse individuals.
2Device complexity
If conventional breath collection methods are used without cross-contamination prevention, then device complexity is reduced, but reliability deteriorates due to VOC contamination between subjects
Solution Approach 1:
The system extracts and removes trapped breath samples from the collection chamber between subjects using a purge gas flow. This active clearing process ensures that residual VOCs from previous subjects are eliminated before the next sampling begins, preventing cross-contamination while maintaining a relatively simple chamber design.
Solution Approach 2:
The system performs preliminary purging of the collection chamber and sampling lines between subjects to prevent contamination. By proactively clearing residual gases before the next subject's sample is collected, the system ensures reliability without requiring complex isolation mechanisms during normal operation.
3Quantity of substance
If complete gas collection is performed for analysis, then sufficient sample volume is obtained, but loss of time increases due to handling and analysis of unnecessary gas volume
Solution Approach 1:
The system applies partial action by collecting only the specific portion of expired breath that contains the alveolar phase, identified by CO2 concentration thresholds. Rather than collecting the entire expiration, the system captures only the relevant segment, obtaining sufficient sample volume for analysis while minimizing excess gas collection and subsequent processing time.
4Device complexity
If undesired compounds like nitrogen, oxygen, water vapor, and carbon dioxide are not filtered out, then device complexity is minimized, but measurement precision deteriorates due to interference with VOC detection
Solution Approach 1:
The system employs porous sorbent materials in the sampling device that selectively adsorb VOCs while allowing larger molecules like water vapor and excess nitrogen and oxygen to pass through or be excluded. This porous filtration approach removes interfering compounds and concentrates the target analytes, significantly improving measurement precision for trace VOC detection.
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
The apparatus provides accurate and precise collection and storage of VOCs, minimizing cross-contamination and allowing for efficient flushing, enabling the collection of only the required gas volume for analysis, thus improving the reliability of VOC sampling.
Implementation Method 1
The use of thermal desorption tubes to filter out undesired compounds like nitrogen, oxygen, and carbon dioxide
Data Source
AI summary
An apparatus for collecting volatile organic compounds from a gas sample such as alveolar breath or room air comprises an exhaust portion having at least a flow measuring device, and a discriminating device for distinguishing between alveolar and non-alveolar breath. The apparatus further comprises a collection portion distinct from and parallel with the exhaust portion having at least a collection component for receiving and concentrating gas samples within a collection chamber and a sampling component having a plurality of sampling devices for receiving the concentrated gas sample from the collection chamber and isolating VOCs contained in the gas sample. The collection chamber is compressible via a drive mechanism for precisely actuating the chamber to draw a gas sample into the collection chamber and circulating the sample to the sampling devices. Use of a drive mechanism enables the exhaust portion to be distinct from the collection portion, thereby mitigating cross-contamination therebetween.