Bidirectional NO Flow Sensing for Vibration-Stable Gas Delivery
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Solution Overview
Problem
Existing NO delivery devices are sensitive to environmental disturbances such as shocks and vibrations during patient transport, leading to signal saturation and poor regulation of NO flow, which can result in premature closure of the solenoid valve and undesirable rebound effects.
Innovation Solution
A bidirectional flow sensor is used to measure both positive and negative flow rates, allowing the control system to account for vibrations and maintain accurate NO flow regulation, combined with a proportional solenoid valve and flow measurement device to adjust gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensitive flow sensor is used to achieve precise NO flow regulation (less than 1 mL/min accuracy), then measurement precision is improved, but the device becomes highly sensitive to environmental disturbances such as shocks and vibrations during patient transport
Solution Approach 1:
The patent introduces an intermediary computational layer that processes raw sensor signals. The microprocessor separates the true flow signal from vibration-induced noise by analyzing signal characteristics and applying filtering algorithms, thereby protecting the measurement system from environmental disturbances while preserving measurement precision
Solution Approach 2:
The system implements feedback control where the microprocessor continuously monitors the flow sensor output and adjusts the solenoid valve position accordingly. This feedback mechanism compensates for vibration-induced signal variations by comparing expected flow values with actual sensor readings and making real-time corrections
2Measurement precision
If the flow sensor is made more sensitive to detect small NO flow rates, then measurement precision is improved, but signal saturation occurs due to environmental disturbances, leading to premature solenoid valve closure
Solution Approach 1:
The microprocessor-based feedback control system continuously monitors sensor output and compares it with target flow values. When vibration causes temporary signal saturation, the feedback loop detects the discrepancy and adjusts the solenoid valve to maintain the correct average flow rate, preventing premature closure
Solution Approach 2:
The system incorporates signal filtering and averaging algorithms that anticipate and compensate for vibration effects before they cause harmful valve closure. By processing signals through computational filters, the system cushions against the impact of environmental disturbances on regulation stability
3Device complexity
If a unidirectional flow sensor is used, then device complexity is reduced, but the sensor cannot distinguish between positive and negative flow directions, causing inaccurate flow measurement during vibrations
Solution Approach 1:
The patent employs dynamic signal processing where the microprocessor analyzes the temporal characteristics of flow sensor signals. By detecting the direction and magnitude of flow changes over time, the system can distinguish between positive and negative flows even with a unidirectional sensor, effectively adding directional detection capability through computational dynamics
Solution Approach 2:
The invention replaces the need for a mechanically complex bidirectional sensor with a computationally-based solution. The microprocessor substitutes for the mechanical directional detection mechanism by analyzing pressure differential patterns and flow rate changes over time to infer flow direction, thereby reducing device complexity while maintaining measurement precision
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 bidirectional flow sensor effectively mitigates the impact of vibrations, ensuring stable NO delivery by preventing premature solenoid valve closure and maintaining consistent NO flow rates during transport, thereby enhancing patient safety.
Implementation Method 1
the more sensitive the flow sensor, the more it will also pick up environmental disturbances, particularly shocks and/or vibrations
Implementation Method 2
one or more proportional solenoid valve type actuators
Data Source
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AI summary
The invention relates to a device (1) for delivering a gas containing NO, comprising an internal gas circuit (200) with flow control means (220, 230, 240) for controlling the gas flow, in particular a proportional solenoid valve (220) and a flow measurement device (230). Control means (210) cooperate with the flow control means to allow, prohibit, or adjust the gas flow within the internal gas circuit. The flow measurement device includes a bidirectional flow sensor configured to perform positive and negative flow measurements of the NO-containing gas flowing in the internal gas circuit and to provide said flow measurements to the control means.