Shear Wave Dispersion Analysis for Depth-Resolved Elasticity Measurement
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Solution Overview
Problem
Existing non-invasive methods for measuring the elasticity of materials, such as skin, only provide information on the surface layer and fail to measure mechanical properties of sub-layers like the dermis and hypodermis.
Innovation Solution
A method involving the generation of shear waves with different frequencies at the material's surface, measuring surface displacement over time at multiple points, determining phase velocities, and transforming these into a dispersion curve to obtain a profile of phase velocities as a function of depth, representing material elasticity at various depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If surface wave measurement method is used, then non-invasive measurement is achieved, but only surface layer elasticity can be measured
Solution Approach 1:
The patent segments the measurement information by utilizing multiple frequencies to probe different depths. Low frequencies penetrate deeper into sub-layers while high frequencies remain at the surface, effectively dividing the measurement space vertically to obtain depth-resolved elasticity data without invasive procedures
Solution Approach 2:
The patent transitions from two-dimensional surface measurement to three-dimensional depth-resolved measurement by incorporating the frequency dimension. Different frequencies correspond to different penetration depths, adding a vertical dimension to the measurement and enabling characterization of subsurface layers
2Device complexity
If single frequency measurement is used, then measurement simplicity is maintained, but depth resolution is lost
Solution Approach 1:
The patent changes the frequency parameter of the excitation signal to achieve depth resolution. By measuring at multiple frequencies and analyzing the dispersion characteristics, the system can distinguish between surface and subsurface mechanical properties without significantly complicating the measurement procedure
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
Enables non-invasive measurement of material elasticity across multiple layers, providing detailed mechanical property analysis without invasive procedures, applicable to various viscoelastic materials including human and artificial skin.
Implementation Method 1
deforming the material at an impact point using a stimulator to generate a shear wave comprising components at different frequencies
Implementation Method 2
measuring, using a measurement device, the displacement of the surface of the material over time at at least three measurement points
Implementation Method 3
transforming said dispersion curve into a profile of phase velocities as a function of depth, the phase velocity at a given depth being a physical quantity representative of the elasticity of the material at said depth
Data Source
AI summary
A non-invasive method for measuring a physical quantity representative of the elasticity of a material, including: determining the phase velocities of the fundamental mode of the various components of a shear wave generated at the surface of the material, along a measurement axis, the set of pairs, each formed by a frequency f, and the phase velocity Vi of the fundamental mode determined for the frequency fi, forming a dispersion curve of the fundamental mode in a measurement direction parallel to the measurement axis, wherein the index i is an order number of the frequency fi and of the phase velocity Vi, and transforming the dispersion curve into a profile of phase velocities as a function of depth, the phase velocity at a given depth being a physical quantity representative of the elasticity of a material at the depth.