Acoustic Waveguide Multi-Mode Medium Characterization
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Solution Overview
Problem
Existing methods for determining characteristics of liquids and soft materials, such as biological tissues, lack sensitivity and accuracy in measuring physical and chemical properties using acoustic waves.
Innovation Solution
A method and device utilizing an acoustic waveguide with a side structure that excites two distinct acoustic wave modes with different phase velocities, allowing for more accurate determination of medium characteristics by analyzing amplitude and time differences in received signals, which are influenced by dispersion properties and mode conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single acoustic wave mode is used in the waveguide side structure, then the measurement method is simple, but the sensitivity and accuracy in determining medium characteristics are insufficient
Solution Approach 1:
The acoustic waveguide mode is segmented into multiple distinct wave modes (first wave mode and second wave mode) with different phase velocities. Each mode provides separate measurement information about the medium characteristics, thereby improving measurement precision through multiple independent measurement channels rather than relying on a single mode.
Solution Approach 2:
The invention changes the parameter of phase velocity by exciting multiple wave modes with different phase velocities in the waveguide side structure. This parameter differentiation allows for more accurate determination of medium characteristics through comparison and analysis of the different propagation characteristics of each mode.
2Measurement precision
If multiple wave modes with different phase velocities are excited in the waveguide side structure, then the sensitivity and accuracy in determining medium characteristics are enhanced, but the complexity of the measurement system increases
Solution Approach 1:
The waveguide side structure acts as an intermediary that naturally supports and separates multiple wave modes with different phase velocities. This intermediary structure facilitates the excitation and propagation of distinct acoustic modes, enabling enhanced measurement capability while the waveguide itself manages the complexity of mode differentiation.
Solution Approach 2:
The invention utilizes the dynamic propagation characteristics of multiple acoustic wave modes traveling through the waveguide side structure. By analyzing the time-dependent and velocity-dependent behavior of different modes, the system extracts more information about medium characteristics, transforming the complexity of multiple modes into a beneficial dynamic measurement approach.
3Measurement precision
If the thickness of the waveguide side structure and acoustic wave frequency are optimized to excite multiple wave modes, then the determination of medium properties becomes more accurate, but the design and manufacturing complexity increases
Solution Approach 1:
The invention systematically varies the parameters of waveguide thickness and acoustic wave frequency to optimize the excitation of multiple wave modes. By carefully selecting these parameters, the system achieves accurate determination of medium properties while managing manufacturing complexity through defined parameter ranges and relationships.
Solution Approach 2:
The waveguide side structure is designed with specific local thickness characteristics that enable the excitation of multiple wave modes with different phase velocities. This localized structural optimization allows for enhanced measurement accuracy in specific regions of the waveguide without requiring the entire structure to meet uniformly high manufacturing precision requirements.
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 enhances sensitivity and accuracy in determining properties like density, temperature, viscosity, and sound velocity by generating distinct signals that reflect changes in the medium's properties over time, enabling precise monitoring and evaluation.
Implementation Method 1
energy associated with surface acoustic waves excited in the side structure of the waveguide
Implementation Method 2
at least a part of the energy associated with the acoustic waves excited in the side structure by the transmitter is converted into volume sound waves of the medium (mode conversion)
Implementation Method 3
at least a part of the energy associated with these induced volume sound waves are reconverted into acoustic wave energy of the wave guide side structure thereby generating acoustic waves in the waveguide side structure
Implementation Method 4
The difference of the amplitudes and the arrival times result from the dispersion properties of the waveguide side structure material, i.e. the relation between the phase velocity of an acoustic wave in the waveguide side structure and the thickness of the waveguide side structure and the frequency of the waves excited in the side structure
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3
AI summary
The invention relates to method and a device for determining characteristics of a medium, the method comprising the steps of: a) providing an acoustic waveguide (2) having a side structure (21, 22) delimiting an interior space filled with the medium (3) to be characterized such that an inner surface (215, 225) of the side structure (21, 22) forms an interface with the medium (3), b) exciting acoustic waves (B) in the waveguide side structure by means of at least one transmitter (4), c) converting at least a part of the energy associated with the acoustic waves (B) excited in the side structure into volume sound waves (A) of the medium (3), d) reconverting at least a part of the energy associated with the volume sound waves (A) into acoustic wave energy of the wave guide side structure (21, 22) thereby generating acoustic waves in the waveguide side structure, e) receiving acoustic waves (A, B) evoked by the transmitter (4) by at least one receiver (51 ), f) determining characteristics of the medium (3) from a signal (U) generated by the receiver (51, 52) upon receipt of acoustic waves (A, B) evoked by the transmitter (4). According to the invention the thickness (d1, d2, d3) of the waveguide side structure (21, 22), defined as the distance between the inner surface (215, 225) and an outer surface (21 1, 221 ) of the waveguide side structure, and the frequency (f) of the acoustic waves (B) excited in the waveguide side structure (21, 22) are chosen in such a way that a first wave mode evoking a first signal of the receiver (51, 52) and a second wave mode evoking a second signal of the receiver (51 ) are excited in the waveguide side structure (21, 22), and characteristics of the medium (3) are determined using the first and the second signal. In another aspect of the invention the thickness (di, d2, d3) of the waveguide side structure (21, 22) and the frequency (f) of the acoustic waves excited in the waveguide side structure are chosen in such a way that the velocity of the acoustic waves excited in the waveguide side structure compares to the sound velocity of the medium (3).