Ultrasonic Probe Backing Thermal Resistance and Attenuation
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Solution Overview
Problem
Ultrasonic probes face challenges in enhancing both radiation properties and ultrasonic attenuation properties, leading to degradation in image quality due to insufficient attenuation of ultrasonic waves by existing backing materials.
Innovation Solution
An ultrasonic probe design featuring a backing with a thermal resistance of 8 K/W or less, which effectively attenuates ultrasonic waves by 10 dB or more at the lowest frequency, improving both thermal management and ultrasonic wave attenuation while maintaining high radiation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the backing is increased to enhance ultrasonic attenuation, then ultrasonic wave reflection from the rear surface is reduced, but thermal radiation properties deteriorate and heat accumulates in the piezoelectric element
Solution Approach 1:
The patent changes the physical parameters of the backing material by controlling the density of graphite flakes (0.05-5.0 vol%) and the thickness of the backing (0.1-5.0 mm) to achieve optimal balance between ultrasonic attenuation and thermal radiation. By adjusting these parameters, the backing can attenuate ultrasonic waves effectively while maintaining sufficient thermal conductivity for heat dissipation.
Solution Approach 2:
The patent uses composite materials consisting of a polymer matrix (such as epoxy resin or silicone rubber) combined with graphite flakes as filler. This composite structure provides both ultrasonic attenuation through the polymer matrix and thermal radiation through the graphite flakes, resolving the contradiction between these two opposing requirements.
2Temperature
If graphite or high thermal conductivity materials are used in the backing to improve thermal radiation, then heat dissipation is enhanced, but ultrasonic attenuation properties deteriorate
Solution Approach 1:
The patent applies local quality by distributing graphite flakes with specific density (0.05-5.0 vol%) throughout the polymer matrix of the backing. This creates localized regions of thermal conductivity enhancement while maintaining overall ultrasonic attenuation through the polymer matrix, allowing simultaneous achievement of both heat dissipation and ultrasonic wave suppression.
Solution Approach 2:
The patent optimizes the concentration of graphite flakes (0.05-5.0 vol%) and backing thickness (0.1-5.0 mm) to achieve the right balance. At these specific parameter ranges, the graphite provides sufficient thermal radiation while the polymer matrix maintains effective ultrasonic attenuation, preventing the deterioration of attenuation properties.
3Temperature
If thin plates of thermal conductors are arranged in the backing material to enhance radiation, then thermal properties improve, but ultrasonic waves are reflected inside the thin plates and attenuation properties deteriorate
Solution Approach 1:
The patent changes from using thin plate structures to using flake-shaped graphite particles with controlled volume density (0.05-5.0 vol%). This parameter change eliminates the ultrasonic reflection problem caused by thin plates while maintaining thermal radiation effectiveness through the flake structure and optimized concentration of graphite particles in the polymer matrix.
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 enhances image quality by effectively attenuating low-frequency ultrasonic waves, reducing thermal buildup, and maintaining high radiation properties, even with increased backing thickness, thus addressing the limitations of previous designs.
Implementation Method 1
The ultrasonic probe has a piezoelectric element transmitting and receiving ultrasonic waves, and the like built-in. The piezoelectric element receives an electric signal (transmission signal) from the ultrasonic diagnostic apparatus, converts the received transmission signal into an ultrasonic signal, transmits the ultrasonic signal, receives ultrasonic waves reflected in the living body, converts the ultrasonic waves into an electric signal (reception signal)
Implementation Method 2
The backing attenuates (including, absorbs and scatters) ultrasonic waves transmitted from the piezoelectric element to the rear surface side and suppresses, for example, occurrence of noise (artifact) caused by the ultrasonic waves transmitted to the rear surface side being reflected from a backing end face
Implementation Method 3
The backing releases heat from the piezoelectric element to the rear surface side and suppresses overheat or the like of an acoustic lens being in contact with the subject, which is caused by heat generated in the piezoelectric element
Data Source
AI summary
An ultrasonic probe includes: a piezoelectric element that is used for transmitting and receiving ultrasonic waves; a signal electrode that is disposed at a rear surface side of the piezoelectric element; and a backing that is disposed at a rear surface side of the signal electrode, wherein the backing has a thermal resistance of 8 K/W or less, and the backing attenuates an ultrasonic wave with the lowest frequency by 10 dB or more, among frequencies at which transmittance and reception sensitivity of the ultrasonic probe is decreased from the maximum value thereof by 20 dB.