Single-Sensor Tensiometer for Compact Connective-Tissue Force Measurement
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Solution Overview
Problem
Existing methods for measuring tissue stress, such as those used in ligaments, tendons, and muscles, are invasive, cumbersome, and suffer from frequency-dependent variability and a large device footprint unsuitable for short tissues.
Innovation Solution
A compact shear wave sensor using a single sensor/actuator pair with shaped wavelet excitation for reduced frequency-dependent variability, employing group and phase delay measurements to determine tissue force accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single sensor/actuator pair is used, then the device footprint is reduced, but measurement accuracy deteriorates due to frequency-dependent variability
Solution Approach 1:
The patent changes the excitation signal parameters from broadband impulsive excitation to shaped wavelet excitation with specific frequency content. This parameter change allows the system to operate with a single sensor while maintaining measurement accuracy by reducing frequency-dependent variability through controlled wavelet characteristics
Solution Approach 2:
The patent employs periodic shaped wavelet excitation signals rather than single impulsive excitations. The periodic nature of the wavelet excitation enables better characterization of wave propagation through the tissue, improving measurement precision with a single sensor by providing multiple cycles of information for analysis
2Device complexity
If broadband impulsive excitation is used, then the device can be simpler, but frequency dispersion causes variability in wave speed measurements
Solution Approach 1:
The patent modifies the excitation signal parameters from broadband impulse to shaped wavelet with specific frequency content and temporal characteristics. This parameter change reduces frequency dispersion effects by concentrating energy at optimal frequencies for tissue wave propagation, thereby improving measurement reliability without significantly increasing device complexity
Solution Approach 2:
The patent replaces simple impulsive mechanical excitation with shaped wavelet excitation that utilizes the tissue's own mechanical properties more effectively. The wavelet excitation is designed to interact optimally with the tissue's wave propagation characteristics, substituting a more sophisticated signal approach for a simpler mechanical one
3Length of moving object
If the device footprint is made compact, then it becomes suitable for short tissues, but the measurement capability deteriorates
Solution Approach 1:
The patent changes the excitation parameters to shaped wavelets with optimized frequency content and duration. This allows the compact device to achieve sufficient measurement capability by ensuring that the wavelet excitation provides adequate spatial and temporal information even over short distances, compensating for the reduced measurement baseline
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
Provides accurate, real-time force measurements with reduced susceptibility to frequency dispersion, suitable for a wide range of tissues, including those with short free lengths.
Implementation Method 1
a transducer probe which receives a transmission waveform signal to generate a predefined excitation in the connective tissue at a transmission time to generate a shear wavelet that travels longitudinally along the connective tissue
Implementation Method 2
A motion sensor, also held by the at least one support, detects a reception waveform signal of the wavelet in the tissue at a reception time
Implementation Method 3
A processing circuit operates to determine a wavelet delay from the transmission waveform signal and the reception waveform signal, and, based on the wavelet delay, output a measure of wave speed
Data Source
AI summary
An apparatus for measuring forces in connective tissue employs a single sensor receiving a shear wave, band-limited, wavelet signal from an actuator and processing it to determine a delay for the determination of shear wave speed and related tension or force. Delay may be a combined analysis of a group delay of the wavelet and a phase delay of the wavelet.