Nitric Oxide Sensor Stabilization via Reducing Gas
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Solution Overview
Problem
Current respiratory monitoring devices face challenges in accurately measuring exhaled nitric oxide (eNO) due to the unselectivity of traditional sensors, which struggle to distinguish between nitric oxide (NO) and nitrogen dioxide (NO2), and experience signal instability over time, leading to erroneous readings and high maintenance costs.
Innovation Solution
A measurement system using a catalytic filter comprising platinum and zeolite to form an equilibrium mixture of NO and NO2, combined with a sensor featuring potentiometric electrodes on a solid electrolyte yttria-stabilized zirconia (YSZ) substrate, and the introduction of a reducing gas to stabilize sensor signals, allowing for accurate and prolonged NOx concentration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensors are used to detect nitric oxide, then the device can provide eNO information, but the sensors are unselective and cannot distinguish between NO and NO2, resulting in erroneous readings
Solution Approach 1:
The detection system is segmented into multiple functional components: a catalytic converter that selectively converts NO2 to NO, and a sensor that specifically detects NO. This segmentation allows the system to measure total NOx by converting all NO2 to NO and then detecting the combined NO signal, thereby distinguishing between NO and NO2 contributions and eliminating cross-interference.
Solution Approach 2:
A catalytic converter acts as an intermediary component between the breath sample and the sensor. This mediator selectively converts NO2 to NO through catalysis, enabling the sensor to indirectly measure total NOx concentration by detecting the converted NO signal, thus resolving the selectivity issue.
2Productivity
If traditional sensors are used for eNO measurement, then the device can operate, but the sensor signals become unstable over time, leading to high maintenance costs
Solution Approach 1:
The system replaces traditional mechanical or chemical sensors with an electrochemical sensor that measures potential difference. This substitution provides more stable signals over time because electrochemical sensors have no moving parts and rely on stable electrochemical reactions at the electrode-electrolyte interface, reducing drift and maintenance needs.
Solution Approach 2:
The invention changes the measurement parameter from direct resistance or voltage changes in traditional sensors to potential difference measurement in an electrochemical cell. This parameter change improves signal stability because potential difference measurements in electrochemical sensors are less susceptible to drift and environmental variations, enabling continuous operation with maintained reliability.
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 system provides stable and accurate measurements of total NOx concentration, reducing maintenance needs and costs by maintaining sensor stability over extended periods, enabling reliable respiratory monitoring.
Implementation Method 1
a catalytic filter comprising platinum and zeolite to form an equilibrium mixture of NO and NO2
Implementation Method 2
a sensor featuring potentiometric electrodes on a solid electrolyte yttria-stabilized zirconia (YSZ) substrate
Implementation Method 3
the introduction of a reducing gas to stabilize sensor signals
Data Source
AI summary
A measurement system is disclosed that includes features for detecting the presence of nitric oxide from a gas sample, such as exhaled breath. The measurement system includes an assembly that introduces one or more reducing gases into a reactor-sensor assembly to help stabilize the sensor signal response and improve the performance of the assembly over time. Suitable reducing gases include hydrogen gas (H2), carbon dioxide (CO), benzaldehyde, bisphenol A, and other similar compounds. The reducing gas may be introduced directly from one or more surrounding gases or through tubing or inline piping. The reducing gas may be generated from the liquid or solid forms.