Cylindrical Transducer Configuration for Axial Flow Measurement
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Solution Overview
Problem
Conventional Doppler ultrasound methods for measuring fluid flow in vessels are inaccurate as they often assume flow to be parallel to the vessel axis and sample only a small portion of the flow, leading to extrapolation errors and incomplete measurements.
Innovation Solution
A configuration of cylindrical diffraction-grating (DGT) and non-diffraction-grating (non-DGT) transducers is used, which produces equiphase planes perpendicular to the vessel axis, allowing only axial velocity components to generate Doppler signals, thereby accurately measuring flow without being affected by non-axial components and insonating most of the vessel's cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Doppler ultrasound methods are used to measure fluid flow, then the measurement process is simple, but the measurement precision is poor due to assumptions of parallel flow and sampling only small portions
Solution Approach 1:
The transducer is divided into multiple elements arranged in a specific geometric pattern around the vessel. Each element contributes to insonating a different portion of the vessel cross-section, allowing comprehensive sampling of flow across the entire lumen rather than a small portion, thereby improving measurement precision
Solution Approach 2:
The transducer elements are arranged in a three-dimensional configuration around the vessel (e.g., circumferentially or at multiple angles), transitioning from conventional single-plane sampling to multi-dimensional sampling. This allows simultaneous measurement of flow components in different directions and improves accuracy by capturing the full velocity vector distribution across the vessel cross-section
2Measurement precision
If conventional ultrasound methods sample only a small portion of the flow, then the device complexity is low, but the measurement precision deteriorates due to extrapolation errors
Solution Approach 1:
The transducer configuration is designed to simultaneously perform multiple functions: insonating different regions of the vessel, detecting various flow components, and providing comprehensive velocity data across the entire lumen. This multi-functional approach eliminates the need for extrapolation from small samples and directly measures flow throughout the vessel
3Reliability
If conventional Doppler methods assume flow parallel to vessel axis, then the measurement process is simplified, but the reliability is poor when flow is non-parallel
Solution Approach 1:
The transducer configuration is designed to dynamically adapt to different flow patterns by using multiple elements that can detect velocity components in various directions. The system can process signals from different elements to resolve the full velocity vector, making it reliable for both parallel and non-parallel flow conditions without requiring fixed flow direction assumptions
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
This approach provides accurate and comprehensive measurements of fluid flow in vessels, even when the flow is not parallel to the vessel axis, by isolating axial velocity components and utilizing the entire lumen for data collection, enhancing the precision and reliability of flow measurements.
Implementation Method 1
a cylindrical DGT (or diffraction-grating transducer)
Implementation Method 2
The wavefronts launched by the cylindrical DGT 102 on opposite walls of the vessel produces planes of 'standing waves'
Implementation Method 3
when they are insonated by a beam of ultrasound their movement creates a Doppler shift in the scattered sound. The amount of shift in frequency, also known as the Doppler shift, is proportional to the number of wavelengths of ultrasound per second that the red blood cell moves
Implementation Method 4
Red blood cells act as scatterers of ultrasound in the MHz frequency region, and when they are insonated by a beam of ultrasound their movement creates a Doppler shift in the scattered sound
Data Source
AI summary
The velocity of fluids containing particles that scatter ultrasound can be measured by determining the Doppler shift of the ultrasound scattered by the particles in the fluid. Measuring fluid flow in cylindrical vessels such as blood vessels is an important use of Doppler ultrasound. This invention teaches using various configurations of cylindrical diffraction-grating transducers and cylindrical non-diffraction-grating transducers that suppress the Doppler shift from non-axial components of fluid velocity while being sensitive to the Doppler shift produced by axial velocity components. These configurations thus provide accurate measurement of the net flow down the vessel, even when the fluid flow is curved or not parallel to the vessel wall.