Diffraction-Grating Transducer for Angled Ultrasound in Vessel Flow Monitoring
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Solution Overview
Problem
Conventional Doppler transducers cannot effectively measure blood flow in artificial grafts due to their inability to fit within the thin walls of prosthetic vessels and produce a Doppler shift when placed flat, as the angle between the ultrasound beam and flow velocity is 90 degrees, resulting in no flow information.
Innovation Solution
The use of diffraction-grating transducers (DGTs) embedded within or attached to the vessel walls, which emit and receive ultrasound, allowing for pulsed excitation and enabling flow monitoring even when the velocity vector is not parallel to the vessel wall, using a configuration that produces beams at an angle to the perpendicular, facilitating accurate flow measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional Doppler transducer is placed flat against the vessel wall, then the transducer can be easily installed, but the angle between the ultrasound beam and flow velocity becomes 90 degrees, resulting in no flow information
Solution Approach 1:
The patent uses an asymmetric diffraction grating structure where the groove orientation is deliberately angled relative to the transducer face. This asymmetric configuration causes the ultrasound beam to diffract at a specific angle (e.g., 30-60 degrees) rather than perpendicular to the transducer, thereby achieving a non-90 degree angle with the blood flow while maintaining flat placement against the vessel wall.
Solution Approach 2:
The patent changes the physical parameter of the ultrasound beam direction by using the diffraction grating's groove spacing and orientation. By adjusting the grating geometry parameters (groove spacing d, groove angle), the beam angle θ is controlled to satisfy the diffraction condition sin(θ) = λ/d, thereby optimizing the angle between beam and flow for maximum Doppler shift.
2Measurement precision
If a Doppler transducer is angled at 30 degrees to achieve proper beam orientation, then flow measurement is possible, but the transducer cannot fit inside the thin 0.5 mm wall of a graft
Solution Approach 1:
The patent embeds the diffraction grating transducer within the thin graft wall structure. The transducer is fabricated as a thin-film device that can be integrated into the wall, with the diffraction grating pattern formed directly on or within the transducer membrane, allowing it to nest within the constrained 0.5 mm wall thickness while maintaining the required beam angle through diffraction.
Solution Approach 2:
The patent resolves the thickness constraint by using diffraction to achieve beam angling in a different dimensional approach. Instead of physically tilting the transducer body (which would increase thickness), the beam angle is achieved through wave diffraction in the acoustic dimension, allowing a flat, thin transducer to produce an angled beam that satisfies flow measurement requirements.
3Measurement precision
If multiple transducers are used to achieve pulsed operation with proper beam angles, then accurate flow measurement is possible, but the device complexity and fabrication difficulty increase
Solution Approach 1:
The patent makes a single transducer perform multiple functions: it acts as both the ultrasound source and the beam angle controller through its integrated diffraction grating structure. The diffraction grating is formed as part of the transducer assembly, eliminating the need for separate beam-steering components or multiple angled transducers, thereby simplifying the overall device while maintaining measurement accuracy.
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 allows for practical flow monitoring in artificial grafts and natural vessels by enabling the use of pulsed or continuous wave operation with a single transducer, providing accurate flow measurements regardless of the flow's orientation relative to the vessel wall, with potential for reduced power consumption and simpler fabrication.
Implementation Method 1
at least one implantable diffraction-grating transducer being embedded within or adjacent to a vessel wall, the diffraction-grating transducer being suitable for emitting ultrasound into or receiving Doppler shifted ultrasound from the blood flow
Implementation Method 2
the Doppler shift is indicative of the blood flow
Data Source
AI summary
A system for monitoring blood flow confined by at least one vessel wall, the system including: at least one implantable diffraction-grating transducer being embedded within or adjacent to a vessel wall, the diffraction-grating transducer being suitable for emitting ultrasound into or receiving Doppler shifted ultrasound from the blood flow; and, a source for pulse-exciting the implantable diffraction grating; wherein, the Doppler shift is indicative of the blood flow.