Portable Spirometer Flow Chamber Segmentation
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Solution Overview
Problem
Conventional spirometers face challenges in accurately measuring lung function across a wide dynamic range of flow rates, are often costly or large, and have design issues that lead to measurement inaccuracies and user difficulties, limiting their portability and usability for remote monitoring of respiratory conditions.
Innovation Solution
A portable spirometer with a tubular housing and flow chamber featuring an elongated resistive element and pressure sensor that ensures laminar flow, eliminating moving parts and allowing wireless connectivity to mobile devices for remote data monitoring and analysis, along with a method for evaluating lung function using fluid flow data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional spirometers use differential pressure sensors with obstructions in the flow channel, then measurement capability is achieved, but measurement precision deteriorates across wide dynamic range of flow rates
Solution Approach 1:
The flow channel is divided into multiple segments: an initial section with a first cross-sectional area, a middle section with a reduced second cross-sectional area containing the obstruction, and a final section with a third cross-sectional area. This segmentation allows the obstruction to be isolated in a specific zone, enabling accurate pressure differential measurement without compromising the overall flow measurement capability across wide dynamic ranges.
Solution Approach 2:
Different sections of the flow channel are given different cross-sectional areas to optimize local flow characteristics. The middle section has a reduced area to concentrate flow through the obstruction for accurate sensing, while the initial and final sections have larger areas to accommodate high flow rates during forced expiration, thus achieving both precision and adaptability.
2Measurement precision
If conventional spirometers are designed for accurate measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The obstruction element is integrated directly into the flow channel structure rather than being a separate component. The flow channel itself is shaped to create the required cross-sectional area variations, merging the flow guidance function with the measurement function, thereby reducing overall device complexity while maintaining measurement precision.
3Measurement precision
If conventional spirometers use fine wire mesh or ceramic screen obstructions, then measurement capability is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The obstruction is designed as a simple geometric feature of the flow channel rather than a delicate fine wire mesh or ceramic screen that requires high manufacturing precision. This simplified obstruction can be easily fabricated using standard manufacturing techniques, reducing both manufacturing precision requirements and potential sources of measurement error.
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 solution provides reliable, accurate, and portable lung function monitoring, enabling remote tracking and management of respiratory conditions, improving patient health and treatment adherence while reducing costs and complexity.
Implementation Method 1
A pressure sensor is disposed within the housing. The pressure sensor is in fluid communication with the first opening and the second opening for sensing a pressure differential between the first opening and the second opening and producing an electric signal in response to fluid flow through the housing.
Implementation Method 2
The flow chamber conditions fluid flow for accurate sensing of the flow over a range of fluid flow through the housing
Data Source
AI summary
A spirometer comprises a housing defining a fluid flow pathway extending between a first end and a second end, a first opening along the pathway and a second opening longitudinally spaced along the pathway from the first opening. A flow chamber defining a fluid flow pathway is disposed within the housing between the first opening and the second opening, the flow chamber including an elongated resistive element along the central longitudinal axis of the flow chamber for defining a flow passage through the flow chamber between the resistive element and the inner surface of the flow chamber. The flow chamber conditions fluid flow for accurate sensing of the fluid flow over a range. A pressure sensor is disposed within the housing in fluid communication with the first opening and the second opening for sensing a pressure differential between the first opening and the second opening and producing an electric signal that corresponds with the rate of fluid flow through the housing. The described spirometer and associated software has a variety of applications in the evaluation, diagnosis, monitoring, and improvement of respiratory conditions as well as digitally-delivered respiratory rehabilitation programs and clinical trials.